# GCN_circulars

GRB_name: GRB230410A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33603
SUBJECT: GRB 230410A: Fermi GBM Final Real-time Localization
DATE:    23/04/10 11:36:21 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM  <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 11:26:00 UT on 10 Apr 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230410A (trigger 702818765.135562 / 230410476).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 352.3, Dec = 22.9 (J2000 degrees, equivalent to J2000 23h 29m, 22d 53'), with a statistical uncertainty of 2.1 degrees.

The angle from the Fermi LAT boresight is 72.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230410476/quicklook/glg_skymap_all_bn230410476.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230410476/quicklook/glg_healpix_all_bn230410476.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230410476/quicklook/glg_lc_medres34_bn230410476.gif


GRB_name: GRB230410B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33604
SUBJECT: GRB 230410B: AGILE detection of a burst
DATE:    23/04/11 14:47:31 GMT
FROM:    Francesco Verrecchia at SSDC,INAF-OAR  <francesco.verrecchia@ssdc.asi.it>

F. Verrecchia (SSDC, and INAF/OAR), C. Casentini (INAF/IAPS), M. Tavani
(INAF/IAPS and Uni. Roma Tor Vergata), C. Pittori, F. Lucarelli (SSDC,
and INAF/OAR), A. Argan, M. Cardillo, Y. Evangelista, L. Foffano,
G. Piano (INAF/IAPS), A. Addis, L. Baroncelli, A. Bulgarelli, A. Di
Piano, V. Fioretti, G.Panebianco, N. Parmiggiani (INAF/OAS-Bologna),
M. Romani (INAF/OA-Brera), M. Marisaldi (INAF/OAS-Bologna, Bergen
University), M. Pilia, A. Trois (INAF/OA Cagliari), I. Donnarumma,
E. Menegoni, A.Ursi (ASI), A. Giuliani (INAF/IASF-Mi) and P. Tempesta
(TeleSpazio), report on behalf of the AGILE Team:

The AGILE Mini-CALorimeter (MCAL) detected a short burst at
T0 = 2023-04-10 04:31:20.09 Â± 0.01 s (UTC).
The event lasted 0.13 s and released a total number of 227 counts in the
MCAL detector (in the 0.4-100 MeV energy range), above a background rate
of 537 Hz. The MCAL light curve can be found at:
https://tools.ssdc.asi.it/ImgView/Agile/GRB230410B_083053_60818588008894555 
.

The burst is also clearly visible in the AGILE scientific ratemeters of
the MCAL detector (0.4-100 MeV), and marginally in that of the
AntiCoincidence (AC; 50-200 keV) detectors.

The event lasted about 1 s and it released a total number of 1690 counts
in the MCAL detector (above a background rate of 1109 Hz), 7078
counts in AC-Top detector (above a background rate of 3263 Hz), and
7271 counts in AC-Lat1 detector (above a background rate of 3171 Hz).
The AGILE ratemeters light curves can be found at
https://tools.ssdc.asi.it/ImgView/Agile/GRB230410B_AGILE_RM_D357 .

Additional analysis of AGILE data is in progress. Automatic MCAL GRB alert
Notices can be found at: https://gcn.gsfc.nasa.gov/agile_mcal.html


GRB_name: GRB230409D
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33605
SUBJECT: GRB 230409D: VZLUSAT-2 detection
DATE:    23/04/11 20:57:04 GMT
FROM:    Marianna Dafcikova at Masaryk University  <500025@mail.muni.cz>

M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory),  N.
Werner  (Masaryk U.), M. Ohno (Hiroshima U.),  L. Meszaros, B. Csak
(Konkoly Observatory), H. Takahashi (Hiroshima U.), F. Munz , M. Topinka,
F. Hroch, N. Husarikova, J.-P. Breuer (Masaryk U.), J. Hudec, J. Kapus, M.
Frajt, M. Rezenov (Spacemanic s.r.o), R. Laszlo (Needronix), G. Galgoczi
(Wigner Research Center/Eotvos U.), N. Uchida (ISAS/JAXA), T. Enoto (Kyoto
U.), Zs. Frei (Eotvos U.), Y. Fukazawa, K. Hirose, H. Matake (Hiroshima
U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), L. L. Kiss (Konkoly
Observatory),  T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka
(Univ of Tokyo), K. Torigoe (Hiroshima U.), P. Svoboda, V. Daniel, J.
Dudas, M. Junas, J. Gromes (VZLU), I. Vertat (FEL ZCU)  -- the
VZLUSAT-2/GRB payload collaboration.

The long duration GRB 230409D (Fermi/GBM detection: trigger no. 702745263;
Konus/Wind detection at 2023-04-09 15:00:59.219; INTEGRAL/SPI-ACS detection
at 2023-04-09 15:00:59) was detected by the GRB detector on board of the
VZLUSAT-2 3U CubeSat (https://www.vzlusat2.cz/en/).

The data acquisition was performed by the GRB detector units no. 0 and no.
1. The detection was confirmed at the peak time 2023-04-09 15:01:08 UTC.
The T90 duration measured by VZLUSAT-2 is 19 s (15 s) and the significance
during T90 reaches 26 sigma (12 sigma) for detector unit no. 0 (no. 1).

The light curve obtained by VZLUSAT-2 is available here:

https://vzlusat2.konkoly.hu/static/share/GRB230409D_GCN_VZLUSAT2.pdf

All VZLUSAT-2 detections are listed at:
https://monoceros.physics.muni.cz/hea/VZLUSAT-2/

The GRB detectors on VZLUSAT-2 are a demonstration payload for a future
CubeSat constellation (Werner et al. Proc. SPIE 2018). Two GRB modules of
VZLUSAT-2 are placed in a perpendicular manner and each consists of a 75 x
75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy
range from ~30 keV to ~1000 keV. VZLUSAT-2 was launched on 2022 January 13
from Cape Canaveral.


GRB_name: GRB230410B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33606
SUBJECT: GRB 230410B: VZLUSAT-2 detection
DATE:    23/04/11 20:58:30 GMT
FROM:    Marianna Dafcikova at Masaryk University  <500025@mail.muni.cz>

M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory),  N.
Werner  (Masaryk U.), M. Ohno (Hiroshima U.),  L. Meszaros, B. Csak
(Konkoly Observatory), H. Takahashi (Hiroshima U.), F. Munz , M. Topinka,
F. Hroch, N. Husarikova, J.-P. Breuer (Masaryk U.), J. Hudec, J. Kapus, M.
Frajt, M. Rezenov (Spacemanic s.r.o), R. Laszlo (Needronix), G. Galgoczi
(Wigner Research Center/Eotvos U.), N. Uchida (ISAS/JAXA), T. Enoto (Kyoto
U.), Zs. Frei (Eotvos U.), Y. Fukazawa, K. Hirose, H. Matake (Hiroshima
U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), L. L. Kiss (Konkoly
Observatory),  T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka
(Univ of Tokyo), K. Torigoe (Hiroshima U.), P. Svoboda, V. Daniel, J.
Dudas, M. Junas, J. Gromes (VZLU), I. Vertat (FEL ZCU)  -- the
VZLUSAT-2/GRB payload collaboration.

The short duration GRB 230410B (AGILE/MCAL detection: GCN 33604; GECAM-B
detection: trigger no. 172) was detected by the GRB detector on board of
the VZLUSAT-2 3U CubeSat (https://www.vzlusat2.cz/en/).

The data acquisition was performed by the GRB detector unit no. 1 with a
temporal resolution of 1 s. The light curve shows a spike within one bin at
2023-04-10 04:31:18 UTC. The detection significance reaches 9 sigma.

The light curve obtained by VZLUSAT-2 is available here:

https://vzlusat2.konkoly.hu/static/share/GRB230410B_GCN_VZLUSAT2.pdf

All VZLUSAT-2 detections are listed at:
https://monoceros.physics.muni.cz/hea/VZLUSAT-2/

The GRB detectors on VZLUSAT-2 are a demonstration payload for a future
CubeSat constellation (Werner et al. Proc. SPIE 2018). Two GRB modules of
VZLUSAT-2 are placed in a perpendicular manner and each consists of a 75 x
75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy
range from ~30 keV to ~1000 keV. VZLUSAT-2 was launched on 2022 January 13
from Cape Canaveral.


GRB_name: GRB230409B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33607
SUBJECT: GRB 230409B: OHP/T193 optical upper limit
DATE:    23/04/12 13:30:17 GMT
FROM:    Benjamin Schneider at MIT  <bschn@mit.edu>

C. Adami (LAM), B. Schneider (MIT), S. Basa (LAM), 
E. Le Floc'h, D. Turpin, D. GÃ¶tz (CEA Paris-Saclay), 
S. D. Vergani (GEPI, Obs. de Paris), report on behalf 
of a larger collaboration:

We observed the field of GRB 230409B (Beardmore et al., GCN 33592) 
using the T193cm telescope at Observatoire de Haute-Provence (France) 
equipped with the MISTRAL spectro-imager. Four exposures were obtained 
in the i-band (2x300s + 2x600s) from 2023 10 April 03:03:03 UT to 
2023 10 April 03:44:17 UT (mid time ~22.3h after trigger). In the combined 
frame, we do not detect any source at the position reported by Evans et al., 
GCN 33594 and Kuin et al., GCN 33595 down to the following 3-sigma limit:

i > 20.6 mag (AB)

The photometric calibration was performed using nearby stars from 
the PanSTARRS catalog and the magnitude is not corrected for Galactic 
extinction.

We acknowledge the excellent support from Observatoire de Haute-Provence, 
in particular Jean-Pierre Troncin.


GRB_name: GRB230409B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33608
SUBJECT: GRB 230409B: Mondy optical upper limit
DATE:    23/04/12 23:21:33 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI), E. Klunko (ISTP), A. Pozanenko (IKI), N. Pankov (HSE) 
report on behalf of GRB IKI FuN:

We observed the field of Swift GRB 230409B (Beardmore et al., GCN 33592) 
with AZT-33IK telescope of Mondy observatory in R-filter on 2023-04-09 
starting (UT) 14:52:05. We do not detect the optical counterpart (Kuin 
et al., GCN 33595) within the enhanced Swift/XRT error box (Evans et 
al., GCN 33594). Preliminary photometry of a stacked image is following

Date       UT start  t-T0     Exp.  Filter   OT   Err.  UL(3sigma)
                     (mid, days)  (s)

2023-04-09  14:52:05 0.42231  26*60 R        n/d  n/d   20.5

The photometry is based on nearby USNO-B1.0 stars.
USNO-B1.0
RA DEC R2
21:58:01.9195200 +52:49:21.982800 15.15
21:58:13.7054400 +52:48:57.002400 15.56
21:57:54.5028000 +52:50:57.080400 15.95

The upper limit does not contradict result reported by Adami et al. (GCN 
33607).


GRB_name: GRB230328B
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33609
SUBJECT: GRB 230328B: redshift lower limit estimating
DATE:    23/04/13 00:02:47 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

P. Minaev (IKI), A. Pozanenko (IKI) report on behalf of GRB IKI FuN:

We analyzed GRB 230328B detected by Swift (Gropp et al., GCN 33527), 
Fermi (Dalessi et al., GCN 33531), Astrosat (Waratkar et al., GCN 
33532), GRBAlpha (Dafcikova et al., GCN 33543), Konus (Svinkin et al., 
GCN 33544). Using publicly available data of GBM/Fermi we estimate the 
duration T_90 = 25.7 +/- 0.5 s in (10 - 300) keV energy band. We also 
performed spectral analysis in a time interval of (-7, 30) s since GBM 
trigger, the best fit is obtained for CPL model with following 
parameters: E_p = 164 +/- 13 keV, alpha = -1.22 +/- 0.04. The fluence of 
F = (1.02 +/- 0.04)E-5 erg/cm**2 is obtained in 10 - 1000 keV energy 
band. Using T_90,i - EH diagram [1] we can classify the burst as type II 
(long) and find the minimal possible redshift value of z = 0.09.

The T_90,i - EH diagram for GRB 230328B can be found in
http://grb.rssi.ru/GRB230328B/GRB230328B_T90i-EH.png

[1] - Minaev, Pozanenko, MNRAS, 492, 1919, 2020


GRB_name: GRB230414A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33610
SUBJECT: GRB 230414A: Fermi GBM Final Real-time Localization
DATE:    23/04/14 08:11:08 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM  <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely SHORT GRB

At 08:00:48 UT on 14 Apr 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230414A (trigger 703152053.984158 / 230414334).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 209.5, Dec = -15.8 (J2000 degrees, equivalent to J2000 13h 58m, -15d 48'), with a statistical uncertainty of 10.2 degrees.

The angle from the Fermi LAT boresight is 102.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230414334/quicklook/glg_skymap_all_bn230414334.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230414334/quicklook/glg_healpix_all_bn230414334.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230414334/quicklook/glg_lc_medres34_bn230414334.gif


GRB_name: GRB230414B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33612
SUBJECT: GRB 230414B: Swift detection of a burst
DATE:    23/04/14 16:27:28 GMT
FROM:    Antonino D'Ai at IASF-PA  <antonino.dai@inaf.it>

A. D'Ai (INAF-IASFPA), E. Ambrosi (INAF-IASFPA),
V. D'Elia (SSDC & INAF-OAR), S. Dichiara (PSU), J.D. Gropp (PSU),
J. A. Kennea (PSU), N. J. Klingler (GSFC/UMBC/CRESSTII),
D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB) and M. A. Williams (PSU)
report on behalf of the Neil Gehrels Swift Observatory Team:

At 16:14:21 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 230414B (trigger=1164180).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 181.071, +53.127 which is 
   RA(J2000) = 12h 04m 17s
   Dec(J2000) = +53d 07' 36"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of about 30 sec.  The peak count rate
was ~400 counts/sec (15-350 keV), at ~5 sec after the trigger. 

The XRT began observing the field at 16:16:29.8 UT, 128.6 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 181.09569, 53.15401 which is equivalent
to:
   RA(J2000)  = 12h 04m 22.97s
   Dec(J2000) = +53d 09' 14.4"
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This
location is 110 arcseconds from the BAT onboard position, within the
BAT error circle. This position may be improved as more data are
received; the latest position is available at
https://www.swift.ac.uk/sper.  We cannot determine whether the source
is fading at the present time. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (1.68 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 2.8
(+2.36/-2.05) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 133 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers none of
the XRT error circle. The 8'x8' region for the list of sources generated
on-board covers 100% of the XRT error circle. The list of sources is typically
complete to about 18 mag. No correction has been made for the expected
extinction corresponding to E(B-V) of 0.017. 

Burst Advocate for this burst is A. D'Ai (antonino.dai AT inaf.it). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)


GRB_name: GRB230414B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33613
SUBJECT: GRB 230414B: Prompt enhanced Swift-XRT position
DATE:    23/04/14 16:50:41 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:

Using  promptly downlinked XRT event data for GRB 230414B, we find an
enhanced XRT position of the afterglow: RA, Dec: 181.09439, 53.15428
which is equivalent to:
   RA (J2000)  = 12 04 22.65
   Dec (J2000) = +53 09 15.4
with an uncertainty of 1.9 arcseconds (radius, 90% confidence).
Analysis of the promptly available data is online at
http://www.swift.ac.uk/sper/1164180.

Position enhancement is is described by Goad et al. (2007, A&A, 476,
1401) and Evans et al. (2009, MNRAS, 397, 1177).

This circular is an official product of the Swift-XRT team.


GRB_name: GRB230414B
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33614
SUBJECT: Swift GRB 230414B: Global MASTER-Net observations report 
DATE:    23/04/14 16:50:47 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, 
G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov,  D.Cheryasov, Ya.Kechin
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev
(Irkutsk State University, API),

L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez 
(INAOE, Guillermo Haro Astrophysics Observatory),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

A. Gabovich, V.Yurkov 
(Blagoveschensk Educational State University)


MASTER-Kislovodsk robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the Swift GRB 230414B ( A. D'Ai et al., GCN 33612) errorbox  1644 sec after notice time and 1703 sec after trigger time at 2023-04-14 16:42:44 UT, with upper limit up to  16.1 mag. Observations started at twilight.  The observations began at zenith distance = 32 deg. The sun  altitude  is -9.8 deg. 

The galactic latitude b = 63 deg., longitude l = 138 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2210174

We obtain a following upper limits.  

Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

    1793 |   MASTER-Kislovodsk |   C |   180 | 16.1 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.


GRB_name: GRB230414A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33615
SUBJECT: GRB 230414A: Mondy optical afterglow candidate
DATE:    23/04/14 17:17:45 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

N. Pankov (HSE), E. Klunko (ISTP), A. Pozanenko (IKI), S. Belkin (IKI) 
report on behalf of GRB IKI FuN:

We observed  the field of Swift GRB 230414A (D'Ai et al. GCN 33612) with 
AZT-33IK telescope of Mondy observatory  in  R-filter on
2023-04-14 starting (UT) 16:41:07. Within prompt enhanced Swift-XRT 
position (Evans et al., GCN 33613) we detect fading  object at the 
position of (J2000) 12 04 22.60 +53 09 16.5  with an error of 0.2 arcsec 
in both coordinates. Since the object is absent in DSS2 and variable we 
suggest the object as an afterglow of GRB 230414A.

Preliminary photometry  of first images is following

Date       UT start  t-T0     Exp.  Filter   OT     Err.  UL(3sigma)
                    (mid, days)  (s)

2023-04-14 16:41:07  0.01859  1x120 R        19.2   0.2   20.0

The photometry is based on nearby USNO-B1.0 stars.


GRB_name: GRB230414B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33616
SUBJECT: GRB 230414B: Nanshan/HMT optical afterglow detection
DATE:    23/04/14 17:26:09 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

T.H. Lu (NAOC), Z.P. Zhu (NAOC, HUST), S.Y. Fu, S.Q. Jiang, X. Liu, D. 
Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:

We observed the field of GRB 230414B detected by Swift (A. D'Ai et al., 
GCN 33612) using the HMT-0.5m telescope located at Nanshan, Xinjiang, 
China. Observations started at 16:19:34 UT on 2023-04-14, i.e., 313s 
after the Swift/BAT trigger, and a series of 20 s, 40 s, 60 s, 90 s 
exposures have been obtained without any filter. Observations are still 
ongoing.

We detected an uncatalogued and varying optical transient (OT) at 
coordinates

R.A. (J2000) = 12:04:22.70
Dec.(J2000) = +53:09:16.38

with an uncertainty of ~ 0.5 arcsec, and it has m(r) ~19.3 mag in the 
co-added image from the initial exposures, calibrated with the nearby 
PanSTAR field in the Sloan r-filter. We thus think that the OT is the 
optical afterglow of the burst.


GRB_name: GRB230414B
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33617
SUBJECT: GRB 230414B (correction GRB name in the GCN 33615): Mondy optical afterglow candidate
DATE:    23/04/14 17:27:27 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

N. Pankov (HSE), E. Klunko (ISTP), A. Pozanenko (IKI), S. Belkin (IKI) 
report on behalf of GRB IKI FuN:

The correct name of GRB in the GCN 33615 should be 230414B.
We apologize for possible inconvenience.


GRB_name: GRB230414B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33618
SUBJECT: GRB 230414B: GROWTH India Telescope afterglow confirmation
DATE:    23/04/14 17:56:54 GMT
FROM:    Varun Bhalerao at Indian Inst of Tech  <varunb@iitb.ac.in>

D. Raman (IITB), A. Suresh (IITB), V. Swain (IITB), H. Kumar (IITB), G. Waratkar(IITB), V. Bhalerao (IITB), G.C. Anupama(IIA), S. Barway (IIA) and K. Angail (IAO) report on behalf of the GIT team:
We observed the field of GRB 230414B detected by Swift ( A. D'Ai et al., GCN 33612) with 0.7m GROWTH-India Telescope (GIT). GIT automatically triggered at 16:17:41 UT, i.e., 3.3 min after the Swift/BAT trigger. We obtained frames in the r' and i' band of 120 sec each. We detected an uncatalogued source at RA 12:04:22.65, Dec: 53:09:15.4 with an uncertainty of 1.9 arcsec. There is no minor planet present at this position. The photometric results follow as:
----------------------------------------------------------------------

JD (mid) | T_mid-T0 (min) | Filter | Magnitude (AB) |

----------------------------------------------------------------------

2460049.18505852 | 12.13 | r' | 19.45 +/- 0.08 |

2460049.18674811 | 14.56 | r' | 19.47 +/- 0.08 |
2460049.19372952 | 24.62 | r' | 19.91 +/- 0.09 |
2460049.18854398 | 17.15 | i' | 19.08 +/- 0.13 |
----------------------------------------------------------------------

The results are consistent with (T.H. Lu et al., GCN #33616; N. Pankov et al., GCN #33617).We encourage photometric for further confirmation and spectroscopic follow-up for redshift measurement. The magnitudes are calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction.
The GROWTH India Telescope (GIT; Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/.


GRB_name: GRB230414A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33619
SUBJECT: Fermi GRB 230414A: Global MASTER-Net observations report 
DATE:    23/04/14 18:15:26 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, 
G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov,  D.Cheryasov, Ya.Kechin
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev
(Irkutsk State University, API),

L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez 
(INAOE, Guillermo Haro Astrophysics Observatory),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

A. Gabovich, V.Yurkov 
(Blagoveschensk Educational State University)


MASTER-SAAO robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 230414A ( Fermi GBM team, GCN 33610) errorbox  32707 sec after notice time and 32748 sec after trigger time at 2023-04-14 17:06:37 UT, with upper limit up to  18.6 mag. Observations started at twilight.  The observations began at zenith distance = 78 deg. The sun  altitude  is -10.8 deg. 

The galactic latitude b = 44 deg., longitude l = 326 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2210136

We obtain a following upper limits.  

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

   32779 | 2023-04-14 17:06:37 |         MASTER-SAAO | (13h 41m 49.95s , -17d 47m 26.5s) |   C |    60 | 16.3 |        
   32870 | 2023-04-14 17:08:09 |         MASTER-SAAO | (13h 50m 07.61s , -17d 48m 34.9s) |   C |    60 | 16.6 |        
   32950 | 2023-04-14 17:09:28 |         MASTER-SAAO | (13h 33m 33.73s , -15d 52m 32.4s) |   C |    60 | 16.9 |        
   33041 | 2023-04-14 17:10:59 |         MASTER-SAAO | (13h 41m 52.62s , -15d 54m 01.8s) |   C |    60 | 17.0 |        
   33121 | 2023-04-14 17:12:19 |         MASTER-SAAO | (13h 51m 02.78s , -19d 41m 26.1s) |   C |    60 | 17.3 |        
   33212 | 2023-04-14 17:13:51 |         MASTER-SAAO | (13h 59m 32.50s , -19d 40m 35.2s) |   C |    60 | 17.3 |        
   33304 | 2023-04-14 17:15:22 |         MASTER-SAAO | (13h 49m 17.81s , -15d 54m 35.5s) |   C |    60 | 17.3 |        
   33383 | 2023-04-14 17:16:42 |         MASTER-SAAO | (13h 57m 42.23s , -15d 54m 43.1s) |   C |    60 | 17.4 |        
   33474 | 2023-04-14 17:18:13 |         MASTER-SAAO | (13h 42m 02.45s , -14d 00m 31.4s) |   C |    60 | 17.6 |        
   33554 | 2023-04-14 17:19:32 |         MASTER-SAAO | (13h 50m 19.32s , -13d 59m 03.9s) |   C |    60 | 17.8 |        
   33646 | 2023-04-14 17:21:04 |         MASTER-SAAO | (13h 57m 40.72s , -17d 46m 36.0s) |   C |    60 | 18.0 |        
   33725 | 2023-04-14 17:22:24 |         MASTER-SAAO | (14h 06m 11.41s , -17d 47m 48.0s) |   C |    60 | 17.9 |        
   33816 | 2023-04-14 17:23:55 |         MASTER-SAAO | (13h 47m 17.76s , -17d 48m 48.5s) |   C |    60 | 17.1 |        
   33816 | 2023-04-14 17:23:55 |         MASTER-SAAO | (13h 41m 44.56s , -17d 48m 23.7s) |   C |    60 | 18.3 |        
   33907 | 2023-04-14 17:25:26 |         MASTER-SAAO | (13h 55m 47.39s , -17d 48m 52.4s) |   C |    60 | 15.8 |        
   33907 | 2023-04-14 17:25:26 |         MASTER-SAAO | (13h 50m 14.13s , -17d 48m 28.2s) |   C |    60 | 18.4 |        
   33987 | 2023-04-14 17:26:46 |         MASTER-SAAO | (13h 39m 03.41s , -15d 53m 08.2s) |   C |    60 | 17.2 |        
   33987 | 2023-04-14 17:26:46 |         MASTER-SAAO | (13h 33m 33.68s , -15d 52m 42.2s) |   C |    60 | 17.9 |        
   34078 | 2023-04-14 17:28:16 |         MASTER-SAAO | (13h 47m 22.65s , -15d 54m 39.1s) |   C |    60 | 17.0 |        
   34078 | 2023-04-14 17:28:16 |         MASTER-SAAO | (13h 41m 52.80s , -15d 54m 13.3s) |   C |    60 | 18.3 |        
   34157 | 2023-04-14 17:29:36 |         MASTER-SAAO | (13h 56m 45.52s , -19d 41m 07.7s) |   C |    60 | 17.8 |        
   34157 | 2023-04-14 17:29:36 |         MASTER-SAAO | (13h 51m 08.55s , -19d 40m 42.7s) |   C |    60 | 18.6 |        
   34248 | 2023-04-14 17:31:07 |         MASTER-SAAO | (14h 05m 10.57s , -19d 41m 58.3s) |   C |    60 | 16.8 |        
   34248 | 2023-04-14 17:31:07 |         MASTER-SAAO | (13h 59m 33.52s , -19d 41m 34.0s) |   C |    60 | 18.5 |        
   34328 | 2023-04-14 17:32:26 |         MASTER-SAAO | (13h 54m 48.16s , -15d 53m 01.0s) |   C |    60 | 16.4 |        
   34328 | 2023-04-14 17:32:26 |         MASTER-SAAO | (13h 49m 18.24s , -15d 52m 34.9s) |   C |    60 | 18.3 |        
   34420 | 2023-04-14 17:33:58 |         MASTER-SAAO | (13h 57m 44.52s , -15d 53m 40.8s) |   C |    60 | 18.4 |        
   34511 | 2023-04-14 17:35:30 |         MASTER-SAAO | (13h 47m 26.91s , -14d 01m 03.9s) |   C |    60 | 17.3 |        
   34511 | 2023-04-14 17:35:30 |         MASTER-SAAO | (13h 41m 59.86s , -14d 00m 35.5s) |   C |    60 | 18.4 |        
   34591 | 2023-04-14 17:36:49 |         MASTER-SAAO | (13h 55m 46.61s , -14d 00m 59.0s) |   C |    60 | 15.9 |        
   34591 | 2023-04-14 17:36:49 |         MASTER-SAAO | (13h 50m 19.43s , -14d 00m 31.5s) |   C |    60 | 18.4 |        
   34681 | 2023-04-14 17:38:20 |         MASTER-SAAO | (14h 03m 17.85s , -17d 47m 23.6s) |   C |    60 | 17.3 |        
   34682 | 2023-04-14 17:38:20 |         MASTER-SAAO | (13h 57m 44.47s , -17d 46m 56.7s) |   C |    60 | 18.6 |        
   34761 | 2023-04-14 17:39:40 |         MASTER-SAAO | (14h 11m 41.67s , -17d 48m 50.5s) |   C |    60 | 15.2 |        
   34761 | 2023-04-14 17:39:40 |         MASTER-SAAO | (14h 06m 08.19s , -17d 48m 23.5s) |   C |    60 | 18.4 |        
   34852 | 2023-04-14 17:41:11 |         MASTER-SAAO | (13h 47m 23.27s , -17d 47m 21.2s) |   C |    60 | 17.8 |        
   34852 | 2023-04-14 17:41:11 |         MASTER-SAAO | (13h 41m 49.93s , -17d 46m 52.6s) |   C |    60 | 18.2 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.


GRB_name: GRB230414B
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33620
SUBJECT: GRB 230414B: 1.3m DFOT Optical observations
DATE:    23/04/14 20:31:18 GMT
FROM:    Ankur Ghosh at ARIES  <ghosh.ankur1994@gmail.com>

Ankur Ghosh, Dimple, Kuntal Misra, Rahul Gupta, Amit K Ror, Amar Aryan, and
Shashi B. Pandey (ARIES) report:


We observed the field of GRB 230414B detected by *Swift* (D'Ai et al. 2023,
GCN 33612) using the 1.3m Devasthal Fast Optical Telescope (DFOT) located
at the Devasthal observatory of Aryabhatta Research Institute of
Observational Sciences (ARIES), Nainital, India. We have taken multiple
frames with an exposure time of 300 seconds in several passbands. We
clearly detected the GRB afterglow within the enhanced *Swift*-XRT error
circle (Evans et al. 2023, GCN 33613) in each image. The estimated
preliminary magnitude is the following:


Date_Start_UT       T_start-T0 (days)    Filter     Exp time (sec)
 magnitude

==============================================================

2023-04-14 17:13:30    ~ 0.041               R               300
  20.06 +/- 0.06


The detection of the GRB afterglow is consistent with Lu et al. 2023, GCN
33616, Pankov et al. 2023, GCN 33617, and Raman et al. 2023, GCN 33618.


The magnitude is not corrected for the Galactic and host extinction in the
direction of the GRB afterglow. Photometric calibration is performed using
the standard stars from the USNO-B1.0 catalog.


GRB_name: GRB230414B
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33621
SUBJECT: GRB 230414B: Enhanced Swift-XRT position
DATE:    23/04/14 21:53:00 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 940 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 230414B, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 181.09469, +53.15434 which is equivalent
to:

RA (J2000): 12h 04m 22.73s
Dec (J2000): +53d 09' 15.6"

with an uncertainty of 2.2 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB230414B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33622
SUBJECT: GRB 230414B: SAO RAS optical observations
DATE:    23/04/14 22:41:49 GMT
FROM:    Moskvitin Alexander at SAO RAS  <mosk@sao.ru>

A. S. Moskvitin (SAO RAS) and V. P. Goranskij (SAI, Moscow University)
report on behalf of a larger collaboration:

We observed the field of GRB 230414B detected by Swift
(D'Ai et al., GCN 33612) with the SAO RAS 1-m telescope
Zeiss-1000 + CCD photometer. We obtained several images in Rc band.

The GRB OT (Pankov et al., GCN 33615; Lu et al., GCN 33616;
Raman et al., GCN 33618; Ghosh et al., GCN 33620) is clearly detected
in the stacked frame with the brightness of R = 19.8 +/- 0.1
(T_mid - T0 = 3.68 hours). This preliminary photometry is based on R2
magnitudes of nearby USNO-B1 stars. The OT magnitude is not corrected
for the Galactic extinction.


GRB_name: GRB230414B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33623
SUBJECT: GRB 230414B: slow optical light curve decay
DATE:    23/04/14 23:47:27 GMT
FROM:    Daniele B Malesani at Radboud U  <d.malesani@astro.ru.nl>

D. B. Malesani (Radboud Univ. and DAWN/NBI), A. de Ugarte Postigo (OCA), 
L. Izzo (DARK/NBI), D. Xu (NAOC), Z.P. Zhu (NAOC, HUST), J. Acevedo 
Barroso (EPFL), C. Lemon (EPFL), Z. Gray (AOP), F. Neira (EPFL), report 
on behalf of a larger collaboration:

We observed the optical afterglow (Pankov et al., GCN 33615; Lu et al., 
GCN 33616; Raman et al., GCN 33618; Ghosh et al., GCN 33620; Moskvitin 
et al., GCN 33622) of GRB 230414B (D'Ai et al., GCN 33612) with the 
Nordic Optical Telescope (NOT) equipped with the ALFOSC imager. In a 
single r-band image obtained on 2023 Apr 14.95 UT (6.57 hr after the 
GRB), we clearly detect the optical afterglow at a magnitude r = 19.42 
+- 0.02 (AB), calibrated against nearby stars from the Pan-STARRS catalog.

Comparing to earlier magnitudes from the above mentioned GCNs, our 
measurement indicates a slow decay or plateau phase, as already hinted 
by the magnitudes reported by Moskvitin et al. (GCN 33622).


GRB_name: GRB230414B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33625
SUBJECT: GRB 230414B: Dabancheng/GHOST optical observations 
DATE:    23/04/15 05:39:21 GMT
FROM:    Zipei Zhu at NAOC  <zpzhu@nao.cas.cn>

Z.P. Zhu (NAOC, HUST), S.Y. Fu, S.Q. Jiang, X. Liu, T.H. Lu, D Xu (NAOC), S.W. Luo, M.M. Yang, Z. K. Feng (Gaoyazi Obs.) reoport:

We observed the field of GRB 230414B detected by Swift (A. D'Ai et al., GCN 33612) with the GHOST-0.5m telescope located at Dabancheng, Xinjiang, 
China. Observations started at 18:27:56 UT on 2023-04-14, i.e., 2.23 hr after the Swift/BAT trigger, and 20x120 s images were obtained all in the Sloan r filter.

The afterglow reported before (Pankov et al., GCN 33615; Lu et al., GCN 33616; Raman et al., GCN 33618; Ghosh et al., GCN 33620; Moskvitin et al., GCN 33622; Malesani et al., GCN 33623) is clearly detected in the stacked image with a brightness of r = 20.1 +/- 0.1 mag, calibrated with nearby stars from the Pan-STARRS catalog.


GRB_name: GRB230414B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33626
SUBJECT: GRB 230414B: Swift-XRT refined Analysis
DATE:    23/04/15 05:39:47 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , J. D. Gropp
(PSU), S. Dichiara (PSU), J.A. Kennea (PSU), K.L. Page (U. Leicester),
A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), M. Capalbi
(INAF-IASFPA) and A. D'Ai report on behalf of the Swift-XRT team:

We have analysed 6.2 ks of XRT data for GRB 230414B (D'Ai et al. GCN
Circ. 33612), from 112 s to 34.3 ks after the  BAT trigger. The data
comprise 17 s in Windowed Timing (WT) mode (the first 10 s were taken
while Swift was slewing) with the remainder in Photon Counting (PC)
mode. The enhanced XRT position for this burst was given by Goad et al.
(GCN Circ. 33613). The late-time light curve (from T0+4.4 ks) is
consistent with a constant source of mean count rate 2.2e-01 ct/sec. A
power-law fit gives an index of -0.07 (+/-0.15).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.97 (+0.16, -0.10). The
best-fitting absorption column is  1.74 (+3.05, -0.07) x 10^20 cm^-2,
consistent with the Galactic value of 1.7 x 10^20 cm^-2 (Willingale et
al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux
conversion factor deduced from this spectrum  is 3.2 x 10^-11 (3.4 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.74 (+3.05, -0.07) x 10^20 cm^-2
Galactic foreground: 1.7 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.97 (+0.16, -0.10)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01164180.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB230409B
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33627
SUBJECT: GRB 230409B: 3.6m DOT near-infrared detection, afterglow confirmation
DATE:    23/04/15 08:39:33 GMT
FROM:    Rahul Gupta at ARIES, India  <rahulbhu.c157@gmail.com>

Rahul Gupta, Amit K. Ror, S. B. Pandey, A. Aryan, K. Misra (ARIES), A. J.
Castro-Tirado (IAA-CSIC), D. Bhattacharya (Ashoka University/IUCAA), and V.
Bhalerao (IITB) report on behalf of a larger collaboration:


GRB 230409B was detected by the Swift Burst Alert Telescope (BAT) at
04:56:57 UT on 9th April 2023 (Beardmore et al., GCN 33592). The prompt
emission mask-weighted BAT light curve consists of a single-peaked
structure with a T90 duration of 9.79 +- 2.59 sec in 15-350 keV energy
range (Palmer et al., GCN 33598). We compare the reported value of BAT
fluence and peak photon flux for this GRB (Palmer et al., GCN 33598) with
all the BAT-detected GRBs sample; this burst is positioned at the
middle-near top of this distribution. We also determine the peak energy of
the burst using BAT energy fluence and peak energy correlation. We
calculated the peak energy of the burst is 61.49 (+23.39, -16.96) KeV; the
softer value of peak energy is consistent with those of long GRBs (Type II).


The Swift XRT detected an X-ray afterglow ~ 101.2 sec after the BAT trigger
(Beardmore et al., GCN 33592). The XRT count-rate light curve could be best
described with a broken power-law model with temporal indices of 0.62
(+0.12, -0.12) and 1.15 (+0.19, -0.18) before and after break time
(~4600-sec post-BAT detection), respectively. As no redshift has been
reported for this source, we modeled the late time time-averaged XRT
spectrum (T0 + 18528 to 113195 sec) considering redshift = 2, roughly
average redshift value for long GRBs (Type II). The spectrum could be
modeled using an absorption power-law with the following spectral
parameters: NH_host= 4.85 (-4.85,+8.76) X 10^{22} cm^{-2} and \beta_x= 0.73
(-0.36,+0.40). Considering the adiabatic deceleration without energy
injection, closure relations indicate that the late time X-ray afterglow
could be best described with \nu_m < \nu < \nu_c spectral regime for ISM
medium for the electron energy index p ~ 2.46.


The Swift UVOT detected a weak fading source within the XRT error circle
(Kuin et al., GCN 33595). We performed the follow-up observations of this
fading optical source using the TANSPEC mounted at the axial port of the
3.6m Devasthal Optical Telescope (DOT) of ARIES Nainital at multiple epochs
in J filter (near-infrared). We report the preliminary brightness of the
afterglow to be J = 20.1 +/- 0.3 mag ~ 0.75 days after the BAT trigger. We
obtained the limiting mag of 20.5 mag ~ 2.7 days post-burst at successive
epochs. Our observations confirm this fading source to be the afterglow of
GRB 230409B.


The magnitude values reported are calibrated against 2MASS nearby stars.


This circular may be cited. 3.6m Devasthal Optical Telescope (DOT) is the
recently commissioned facility in the Northern Himalayan region of India
(long:79 41 04E, lat:29 21 40N, alt:2540m) owned and operated by the
Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital (
https://www.aries.res.in). Authors of this GCN circular thankfully
acknowledge consistent support from the staff members to run and maintain
the 3.6m DOT. We also thank Director ARIES for approving the DDT slot for
the ToO observations.


GRB_name: GRB230414B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33628
SUBJECT: GRB 230414B: AbAO optical observations
DATE:    23/04/15 11:15:00 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI),  R. Ya. Inasaridze (AbAO),  A. Pozanenko (IKI), N. 
Pankov (HSE, IKI), D. Datashvili (AbAO), V. R. Ayvazian (AbAO),   report 
on behalf of GRB IKI FuN:

We observed  the field of Swift GRB 230414B (D'Ai et al., GCN 33612) 
with AS-32 telescope of Abastumani observatory (AbAO) in   R-filter 
starting on Apr. 14 (UT) 16:46:07. We  detected the  afterglow (Pankov 
et al., GCN 33615; Lu et al., GCN 33616; Raman et al., GCN 33618; Ghosh 
et al., GCN 33620; Moskvitin et al., GCN 33622; Malesani et al., GCN 
33623; Zhu  et al., GCN 33625).  Preliminary photometry of the object is 
following

Date       UT start   t-T0    Filter Exp.    OT    Err.  UL(3sigma)
                       (mid, days)    (s)

2023-04-14 16:46:07   0.06094  R     112*60  19.73 0.05    22.3

The photometry is based on nearby USNO-B1.0 stars.


GRB_name: GRB230414B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33629
SUBJECT: GRB 230414B: Redshift from OSIRIS/GTC
DATE:    23/04/15 12:00:39 GMT
FROM:    J. F. Agui Fernandez at IAA-CSIC  <feli@iaa.es>

J. F. Agui Fernandez (IAA-CSIC), C. C. Thoene (ASU-CAS),
A. de Ugarte Postigo (OCA), R. Scarpa, A. Marante and
A. L. Cabrera Lavers (GTC, IAC) report:

We observed the afterglow of GRB 230414B (D'Ai et al. GCN
33612; Evans et al. GCN 33613; Lipunov GCN 33614; Pankov et al.
GCN 33615; Lu et al. GCN 33616; Raman et al. GCN 33618;
Ghosh et al. GCN 33620; Goad GCN 33621; Moskvitin et al.
GCN 33622; Malesani et al. GCN 33623; Zhu et al. GCN 33625)
with OSIRIS at the 10.4m GTC telescope, at the Roque de los
Muchachos Observatory (La Palma, Spain). Observations consisted
of 4x1200 s spectroscopy with grism R1000B, covering the
spectral range between 3700 and 7800 AA.

In a preliminary analysis we identify a broad absorption that we
interpret as due to Ly-alpha. We also see several transitions
coincident with SI, SiII, SiII*, OI, CII, NiII, SiIV, CIV and FeII, all of
them at a common redshift of z = 3.568, which we interpret as
the redshift of the GRB.

This GCN is in honor of the great Alex Kann, the WiseGRBguy.
It happened on the day he was buried while some of
his colleagues were standing at the grave saying farewell.
Even the Universe paid its tribute to him.


GRB_name: GRB230414B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33630
SUBJECT: GRB 230414B: Bassano Bresciano Observatory optical observations
DATE:    23/04/15 14:51:21 GMT
FROM:    Ulisse Quadri at Bassano Bresciano Obs  <oabb@ulisse.bs.it>

U.Quadri, L.Strabla report:

We imaged the field of GRB 230414B detected by SWIFT(trigger 1164180)
with the robotic telescope of (IAU station 565) Bassano Bresciano 
Observatory, Italy. Member of: 
AAVSO - American Association of Variable Star Observers.
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili.

The observations started 236.82 min min after the GRB trigger, at the end of twilight, 
with our Newton telescope D=250 mm F/D=4.8.

We co-added 6 series of 30 exposures of 60 sec each.

Start T0+      End T0+      Vlim
236.82 min   323.07 min     20.5

We detected a (fading) afterglow in the error box of the XRTcandidate.
A. D'Ai (INAF-IASFPA), E. Ambrosi (INAF-IASFPA), et al.
at the following position (+/- 2 arcsec):

RA (J2000) =  12h 04m 22.64s 
DEC(J2000) = +53Â° 09' 16.4"

The results of our photometry are:

-----------------------------------------    
    Date UT               CR-mag   
    Middle                  +/- 0.05
-----------------------------------------
2023 04 14.85273            19.76
2023 04 14.86022            19.74
2023 04 14.86771            19.76
2023 04 14.87519            20.02
2023 04 14.88268            19.96
2023 04 14.89017            20.01

-----------------------------------------

Magnitudes were estimated with the UCAC4 cat. and 
are not corrected for galactic dust extinction.

The images are available at:
http://www.osservatoriobassano.org/GRB.asp

The message may be cited.


GRB_name: GRB230414B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33631
SUBJECT: GRB 230414B: Lulin 40cm-SLT optical limit
DATE:    23/04/15 15:36:17 GMT
FROM:    Ting-Wan Chen at MPE  <janet.chen@astro.su.se>

T.-W. Chen (TUM/MPA), S. Yang (HNAS), C.-S. Lin, C.-C. Ngeow, H.-Y. Hsiao, W.-J. Hou, Y.-C. Pan, H.-C. Lin, and J.-K. Guo (IANCU) report:

We observed the field of GRB 230414B (D'Ai et al. GCN 33612; Evans et al. GCN 33613; Lipunov GCN 33614; Pankov et al. GCN 33615; Lu et al. GCN 33616; Raman et al. GCN 33618; Ghosh et al. GCN 33620; Goad GCN 33621; Moskvitin et al. GCN 33622; Malesani et al. GCN 33623; Zhu et al. GCN 33625; Gupta et al. GCN 33627; Belkin et al. GCN 33628; Agui Fernandez et al. GCN 33629; Quadri & Strabla GCN 33630), using the 40cm-SLT at Lulin Observatory, Taiwan to obtain r-band images as part of the Kinder collaboration (Chen et al., AstroNote 2021-92).

The first epoch of observations started at 17:01 UT on 14 of April 2023 (MJD = 60048.709), 46 minutes (0.032 days) after the Swift/BAT trigger. The images were combined from 6 frames with a 300-second exposure time for the r band, taken under seeing conditions of an average of 1.85" and at a median airmass of 1.37. We note that the QE of the current testing camera mounted on the SLT is much shallower than the previous one. After template subtraction using the SDSS image, we do not detect a source at the position of the afterglow down to the following preliminary 2.5-sigma limit (in the AB system):

r > 19.18 mag.

The given limit is derived based on calibrating against SDSS field stars and is not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V) = 0.01 mag in the direction of the burst (Schlafly & Finkbeiner 2011).


GRB_name: GRB230414B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33634
SUBJECT: GRB 230414B: Montarrenti Observatory late time optical afterglow detection
DATE:    23/04/16 13:28:28 GMT
FROM:    Simone Leonini at Monarrenti Obs  <s.leonini@iol.it>

 Simone Leonini, M. Conti, P. Rosi, L.M. Tinjaca Ramirez (Montarrenti Observatory, Siena, Italy), M.G. Dainotti (National Astronomical Observatory of Japan), Y. Niino (Tokyo University, Institute of Astronomy), K. Kalinowski (Aarhus University, Department of Physics and Astronomy) and B. De Simone (Universita' degli Studi Di Salerno) report: 


 We observed the field of GRB 230414B (Swift trigger 1164180, A. D'Ai et al. GCN 33612; Lipunov GCN 33614; Pankov et al. GCN 33615; Lu et al. GCN 33616; Raman et al. GCN 33618; Ghosh et al. GCN 33620; Moskvitin et al. GCN 33622; Malesani et al. GCN 33623; Zhu et al. GCN 33625; Gupta et al. GCN 33627; Belkin et al. GCN 33628; Agui Fernandez et al. GCN 33629; Quadri & Strabla GCN 33630; Chen et al. GCN 33631) with the automatic 0.53m RC telescope + U47 detector at Montarrenti Observatory (Siena, Italy, IAU code C88). 


 The observations were started in a windy night under mediocre seeing conditions at 2023-04-15 21:18:31 UT (approximately 29 hours after burst) stacking 20x30s unfiltered CCD exposures. 


 The optical afterglow was detected at the following position: 


 RA    (J2000)   12h 04m 22.68s +/-0.22 
Decl. (J2000) +53Â° 09'   17.2"    +/-0.28 


 Preliminary photometry is obtained using nearby USNO-B1 stars as follows: 


 2023 Apr 15.89133 UT (21:23:31 mid-time) CR=21.53 +/-0.18 


 Measures are not corrected for galactic dust extinction 


GRB_name: GRB230307A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33635
SUBJECT: GRB 230307A: iTelescope optical upper limit (likely)
DATE:    23/04/16 15:31:19 GMT
FROM:    Filipp Dmitrievich Romanov at Amateur astronomer  <filipp.romanov.27.04.1997@gmail.com>

On 2023-03-09 I observed the field of GRB 230307A (Fermi GBM team, GCN
Circ. 33405) remotely using the telescope T17 (0.43-m f/6.8 reflector
+ CCD) of iTelescope.Net in Siding Spring Observatory (Australia). Ten
images with exposures of 300 seconds and Ic filter (Astrodon
Johnson-Cousins Ic) were obtained, the midtime of the stacked image is
10:52:40.7 UT (1.8 d. after the trigger). I did not detect a clear
optical afterglow near the Swift-XRT position (Burrows et al., GCN
Circ. 33465), but in this area in the stacked image there is what I
can consider a noise (SNR <2), but I do not exclude that it may be
faint afterglow near the upper limit of about 20 magnitudes in this
band.


GRB_name: GRB230414B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33636
SUBJECT: GRB 230414B: 3.6m DOT Optical observations, slow decay at early epochs
DATE:    23/04/16 19:21:38 GMT
FROM:    Rahul Gupta at ARIES, India  <rahulbhu.c157@gmail.com>

Amit K. Ror, Rahul Gupta, S. B. Pandey, A. Aryan, K. Misra (ARIES), A. J.
Castro-Tirado (IAA-CSIC), D. Bhattacharya (Ashoka University/IUCAA), and V.
Bhalerao (IITB) report on behalf of a larger collaboration:

We observed the field of GRB 230414B (D'Ai et al. GCN 33612; and Evans et
al. GCN 33613) using the TANSPEC mounted at the axial port of the 3.6m
Devasthal Optical Telescope (DOT) of ARIES Nainital. We have taken multiple
frames with an exposure time of 300 sec each in r, and i filters on
2023-04-14 and successive nights. We clearly detect the optical afterglow
(Pankov et al. GCN 33615; Lu et al. GCN 33616; Raman et al. GCN 33618;
Ghosh et al. GCN 33620; Moskvitin et al. GCN 33622; Malesani et al. GCN
33623; Zhu et al. GCN 33625; Belkin et al. GCN 33628; Fernandez et al. GCN
33629; Quadri et al. GCN 33630; and Leonini et al. GCN 33634) in each
individual image taken on 2023-04-14. We report the preliminary brightness
of the afterglow to be i = 19.95 +/- 0.16 mag ~ 43 minutes after the BAT
trigger. By combining our i-band magnitude with the observations of Raman
et al. GCN 33618, we determine the preliminary flux decay index of 0.60
+/-0.08. Our observations indicate the slow flux decay behavior of the
afterglow at the early epoch, as also noted by Malesani et al. GCN
33623. Late-time
observations will further provide insight into jet geometry, circumburst
medium, and the total energy of the burst.

The magnitude quoted is not corrected for the Galactic and host extinctions
in the direction of the burst. Photometric calibration is performed using
the standard stars from the PanSTARRS catalog.


This circular may be cited. 3.6m Devasthal Optical Telescope (DOT) is the
recently commissioned facility in the Northern Himalayan region of India
(long:79 41 04E, lat:29 21 40N, alt:2540m) owned and operated by the
Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital (
https://www.aries.res.in). Authors of this GCN circular thankfully
acknowledge consistent support from the staff members to run and maintain
the 3.6m DOT.


GRB_name: GRB230414B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33637
SUBJECT: VIRT optical transient detection
DATE:    23/04/16 23:44:45 GMT
FROM:    Priya Gokuldass at Florida Tech  <pgokuldass2020@my.fit.edu>

R. Querrard (UVI), K. Smith (UVI), N. Orange (OrangeWave Innovative
Science, LLC), D. Morris (UVI), P. Gokuldass (Florida Tech), and K.
Noonan (UVI)  report:

We observed the field of GRB230414B (D'Ai et al. GCN 33612; Evans et
al. GCN 33613) with the 0.5m Virgin Island Robotic Telescope (VIRT) at
the University of the Virgin Islands' Etelman Observatory on
04-14-2023 starting at 23:35:12 UT (T+7.4hrs). We performed a series
of exposures in R filter with a total exposure of 1080 s. The weather
conditions were mixed during the hours of observation with an average
airmass of ~1.5.

We detect the optical transient reported by others (Pankov et al., GCN
33615; Lu et al., GCN 33616; Raman et al., GCN 33618; Ghosh et al.,
GCN 33620; Moskvitin et al., GCN 33622; Malesani et al., GCN 33623;
Zhu  et al., GCN 33625, Belkin et al., GCN 33628; Agui Fernandez et
al. GCN 33629; Quadri & Strabla GCN 33630; Leonini et al. GCN 33634;
and Ror et al. GCN 33636). We confirm a slow decay or rebrightening as
suggested in earlier reports (Malesani et al., GCN 33623 and Moskvitin
et al., GCN 33622) and report the following magnitude:

T_mid       ||Exposure     ||Filter      ||Magnitude     ||Airmass
T+7.8 hrs â€‚â€‚||1080s        ||R           ||19.1 +/- 0.2   ||1.5

The magnitude is estimated from comparison to nearby USNO B1 stars and
is not corrected for Galactic extinction. Further analysis is in
progress. The VIRT is still in the commissioning phase.

We acknowledge financial support from NASA MUREP MIRO award
80NSSC21M0001, NASA EPSCoR award 80NSSC22M0063, and NSF EiR award
1901296. R.Q. and N.B.O. also acknowledge financial support from South
Carolina Space Grant award 80NSSC20M0054. This message can be cited.


GRB_name: GRB230415A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33639
SUBJECT: GRB 230415A: Swift/BAT-GUANO detection
DATE:    23/04/18 05:44:11 GMT
FROM:    Aaron Tohuvavohu at University of Toronto <aaron.tohu@gmail.com>

Aaron Tohuvavohu (U Toronto), Gayathri Raman (PSU), James DeLaunay (UAlabama), Jamie A. Kennea (PSU), Samuele Ronchini (PSU), Tyler Parsotan (UMBC/GSFC) report:

Swift/BAT did not localize GRB 230415A onboard (T0: 2023-04-15 20:48:48.63 UTC, Fermi/GBM trig #703284533). 

The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). 

Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground.

The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), detects the burst with a sqrt(TS) of 12.6 in a 16.384 s analysis time bin.
The burst duration is ~30 seconds.

NITRATES results, independently, are ambiguous with respect to whether this burst originates from in or outside the BAT FOV.

See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descriptions and interpretation of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut.

GUANO is a fully autonomous, extremely low latency, spacecraft
commanding pipeline designed for targeted recovery of BAT event mode
data around the times of compelling astrophysical events to enable
more sensitive GRB searches.

A live reporting of Swift/BAT event data recovered by GUANO can be
found at: https://www.swift.psu.edu/guano/


GRB_name: GRB230414B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33641
SUBJECT: GRB 230414B: Osservatorio Astronomico Nastro Verde - Sorrento: optical observations
DATE:    23/04/18 16:26:54 GMT
FROM:    Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy - MPC Code C82 <osservatorionastroverde@gmail.com>

I imaged the field of GRB 230414B detected by SWIFT(trigger 1164180)
with telescope of Nastro Verde Observatory - Sorrento (Naples), Italy. Member of: 
AAVSO - American Association of Variable Star Observers.
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili.
AstroCampania Associazione

The observations started at 20:28 UT of  2023/04/14
with principal telescope  SC 0.35 f/10 with focal reduced + CCD Sbig ST10 XME
I took 12 image of 180 sec each. All images are unfiltered stacked with Tycho Tracker software
.

Start T0+                End T0+      
20:28:53 UT         21;26:21 UT

I detected a (fading) afterglow in the error box of the XRTcandidate.
A. D'Ai (INAF-IASFPA), E. Ambrosi (INAF-IASFPA), et al.
at the following position (+/- 2 arcsec):

RA (J2000) =  12h 04m 22.73s 
DEC(J2000) = +53Â° 09' 15.3"

The results of our photometry are:

-----------------------------------------    
    Date UT               CR-mag   
    Middle                  +/- 0.05
-----------------------------------------
2460049.354 19.760887
2460049.359 19.691675
2460049.361 19.481389
2460049.363 19.618392
2460049.365 19.760087
2460049.367 19.909645
2460049.37 19.739394
2460049.374 19.071181
2460049.388 19.378857
2460049.394 21.82892

-----------------------------------------

Magnitudes were estimated with the Gaia DR2 cat. and 
are not corrected for galactic dust extinction.



The message may be cited.


GRB_name: GRB230414B
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33642
SUBJECT: GRB 230414B: Swift/UVOT Detection
DATE:    23/04/18 17:05:38 GMT
FROM:    Sam LaPorte at PSU <sjl5346@psu.edu>

 GRB 230414B: Swift/UVOT Detection

S. J. LaPorte (PSU) and A. D'Ai (INAF-IASFPA)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 230414B
133 s after the BAT trigger (D'Ai et al., GCN Circ. 33612).
A fading source consistent with the optical position
(Pankov et al. GCN Circ. 33615)
is detected in the initial UVOT exposures.

Preliminary detections and 3-sigma upper limits using the UVOT photometric
system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures
are:

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

b                        543           735             38        >19.23
m2                   1070         1089             19        >17.31
u                        287           710           265        >20.09
v                        617         1065             58        >18.53
w1                     666           859             38        >18.48
w2                     766           785             19        >17.72
white_FC          129         1015            481          20.92+-0.22
white               5056         5203            145        >20.64

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.017 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB230415A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33643
SUBJECT: GRB 230415A: Fermi GBM detection
DATE:    23/04/18 17:17:44 GMT
FROM:    Suraj Poolakkil at UAH <sp0076@uah.edu>

S. Poolakkil (UAH) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 20:48:48.63 UT on 15 April 2023, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 230415A (trigger 703284533 / 230415867)
which was also detected by the Swift/BAT-GUANO (Tohuvavohu et al. 2023, GCN 33639).

The angle from the Fermi LAT boresight at the GBM trigger time is 50 degrees.

The GBM light curve consists of multiple peaks followed
by some extended emission with a duration (T90) of about 40 s (50-300 keV).
The time-averaged spectrum from T0 s to T0+34.8 s
is best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.87 +/- 0.09  and
the cutoff energy, parameterized as Epeak, is 250 +/- 31 keV.

The event fluence (10-1000 keV) in this time interval is
(6.3 +/- 0.4)E-06  erg/cm^2. The 1-sec peak photon flux measured
starting from T0+8.3 s in the 10-1000 keV band
is 2.5 +/- 0.2 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"


GRB_name: GRB230414B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33645
SUBJECT: GRB 230414B Swift-BAT refined analysis
DATE:    23/04/18 17:28:11 GMT
FROM:    Tyler Parsotan at UMBC/GSFC/CRESST II <parsotat@umbc.edu>

T. Parsotan (GSFC/UMBC), S. D. Barthelmy (GSFC),

H. A. Krimm (NSF), S. Laha (GSFC/UMBC),

A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),

D. M. Palmer (LANL), T. Sakamoto (AGU),

M. Stamatikos (OSU) (i.e. the Swift-BAT team):


Using the data set from T-239 to T+963 sec from the recent telemetry
downlink,

we report further analysis of BAT GRB 230414B (trigger #1164180)

(D'Ai et al., GCN 33612).  The BAT ground-calculated position is

RA, Dec = 181.052, 53.179 deg which is

   RA(J2000)  =  12h 04m 12.5s

   Dec(J2000) = +53d 10' 44.7"

with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment).

The partial coding was 80%.


The mask weighted light curve shows a single main fast rise exponential
decay type pulse.

T90 (15-350 keV) is 25.98 +- 8.86 sec (estimated error including
systematics).


The time-averaged spectrum from T-1.77 to T+27.14 sec is best fit by a
simple

power-law model.  The power law index of the time-averaged spectrum is

1.60 +- 0.30.  The fluence in the 15-150 keV band is 4.7 +- 1.0 x 10^-07
erg/cm2.

The 1-sec peak photon flux measured from T+9.31 sec in the 15-150 keV band

is 0.6 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence

level.



The results of the batgrbproduct analysis are available at

http://gcn.gsfc.nasa.gov/notices_s/1164180/BA/


GRB_name: GRB230414B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33648
SUBJECT: GRB 230414B: Nickel and KAIT telescope optical observations
DATE:    23/04/18 17:53:50 GMT
FROM:    Weikang Zheng at UC Berkeley <weikang@berkeley.edu>

Sophia Risin, Ivan Altunin, Colin Rushing, WeiKang Zheng and

Alex Filippenko (UC Berkeley) report on behalf of the KAIT GRB team:


We observed the field of GRB 230414B (D'Ai et al., GCN 33612) with

the 1-m Nickel and 0.76-m KAIT telescopes located at Lick observatory,

California. Observations started about 0.57 days after the burst.

A total of 6 images (600s exposure each) in R band were taken with Nickel

telescopes, while KAIT images were taken in clear band, with 60s exposure

and coadded. We clearly detected the optical afterglow

(Pankov et al., GCN 33615; Lu et al., GCN 33616; Raman et al., GCN 33618;

Ghosh et al., GCN 33620; Moskvitin et al., GCN 33622; Malesani et al., GCN

33623; Zhu et al., GCN 33625; Belkin et al., GCN 33628; Fernandez et al.,

GCN 33629; Quadri et al., GCN 33630; Leonini et al., GCN 33634; Ror et al.,

GCN 33636; Querrard et al., GCN 33637; Ruocco, GCN 33641; LaPorte et al.,

GCN 33642) and measure the following magnitude calibrated to the Pan-STARRS1

catalog:


t-t0(days) filter mag   err

0.57       clear  19.6  0.1

0.64       R      19.7  0.1

0.72       clear  20.0  0.2


GRB_name: GRB230402A
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33650
SUBJECT: GRB 230402A: Fermi-LAT detection
DATE:    23/04/18 20:49:24 GMT
FROM:    N. Di Lalla at Stanford University <niccolo.dilalla@stanford.edu>

F. Longo (University and INFN, Trieste), E. Bissaldi (Politecnico and INFN, Bari), N. Di Lalla (Stanford Univ.) and N. Omodei (Stanford Univ.) report on behalf of the Fermi-LAT team:

At 07:32:35.96 on April, 02, 2023 Fermi-LAT detected high-energy emission from GRB 230402A, which was also detected by Fermi-GBM (trigger 702113560 / 230402314, GCN 33553), AGILE (GCN 33555), AstroSat (GCN 33562) and CALET (GCN 33563)

The best LAT on-ground location is found to be

RA, Dec = 96.4, -8.9 (J2000)

with an error radius of 0.4 deg (90 % containment, statistical error only).
This was 24 deg from the LAT boresight at the time of the trigger.

The data from the Fermi-LAT show a significant increase in the event rate that is spatially and temporally correlated with the trigger with high significance.
The 100 MeV - 1 GeV photon flux in the time interval 0-300 s after the GBM trigger is (7 Â± 2)E-06 ph/cm2/s. The estimated photon index above 100 MeV is -2.6 Â± 0.5.

The highest-energy photon is a 1.2 GeV event which is observed 14 seconds after the GBM trigger.

The Fermi-LAT point of contact for this burst is Francesco Longo (francesco.longo@ts.infn.it)

The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.


GRB_name: GRB230418A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33652
SUBJECT: GRB 230418A: Fermi GBM Observation
DATE:    23/04/19 03:51:00 GMT
FROM:    Oliver J Roberts at USRA/NASA <oliver.roberts@nasa.gov>

O.J. Roberts (USRA/NASA-MSFC) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 21:11:33.49 UT on 18 April 2023, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 230418A (trigger 703545098 / 230418883).
The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 47.4, Dec = -12.5 (J2000 degrees, equivalent to
J2000 03h 10m, -12d 30'), with a statistical uncertainty of 5.9 degrees
(radius, 1-sigma containment, statistical only; there is additionally a systematic error
which we have characterized as a core-plus-tail model, with 90% of GRBs having a
3.7 deg error and a small tail suffering a larger than 10 deg systematic error.
[Connaughton et al. 2015, ApJS, 216, 32] ).

The angle from the Fermi LAT boresight at the GBM trigger time is 71 degrees.

The GBM light curve consists of single burst
with a duration (T90) of about 0.25 s (50-300 keV).
The time-averaged spectrum from T0-0.064 s to T0+0.256 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.22 +/- 0.08 and
the cutoff energy, parameterized as Epeak, is 838 +/- 71 keV.

The event fluence (10-1000 keV) in this time interval is
(2.51 +/- 0.08)E-06 erg/cm^2. The 64 msec peak photon flux measured
starting from T0+0.13 s in the 10-1000 keV band
is 31 +/- 1 ph/s/cm^2.

A Band function fits the spectrum equally well with Epeak = 836 +/- 75 keV,
alpha = -0.22 +/- 0.08, and beta = -3.9+/- 1.9.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"


GRB_name: GRB230418A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33653
SUBJECT: GRB 230418A: Swift/BAT-GUANO detection outside the coded FOV
DATE:    23/04/19 07:02:04 GMT
FROM:    Aaron Tohuvavohu at University of Toronto <aaron.tohu@gmail.com>

Samuele Ronchini (PSU), Gayathri Raman (PSU), Jamie A. Kennea (PSU), James DeLaunay (UAlabama), Aaron Tohuvavohu (U Toronto), Tyler Parsotan (UMBC/GSFC) report: 

Swift/BAT did not localize GRB 230418A onboard (T0: 2023-04-18T21:11:33.49 UTC, Fermi/GBM GCN 33652) 

The Fermi notice distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). 

Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground. 

The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), detects the burst with a sqrt(TS) of 31.1 in a 0.256 s analysis time bin. 
The burst duration as seen by BAT is ~0.25 seconds.

NITRATES results indicate a burst coming from outside the FOV, with DeltaLLHOut of -20.
The NITRATES best fit OFOV position is consistent with the Fermi/GBM localization (GCN 33652).

See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descriptions and interpretation of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut. 

GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. 

A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/


GRB_name: GRB230419A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33654
SUBJECT: GRB 230419A: Fermi GBM Final Real-time Localization
DATE:    23/04/19 17:33:30 GMT
FROM:    William Cleveland at NASA-MSFC <william.cleveland@nasa.gov>

The Fermi GBM team reports the detection of a likely SHORT GRB

At 13:37:43 UT on 19 Apr 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230419A (trigger 703604268.398824 / 230419568).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 322.4, Dec = -19.1 (J2000 degrees, equivalent to J2000 21h 29m, -19d 06'), with a statistical uncertainty of 26.0 degrees.

The angle from the Fermi LAT boresight is 132.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230419568/quicklook/glg_skymap_all_bn230419568.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230419568/quicklook/glg_healpix_all_bn230419568.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230419568/quicklook/glg_lc_medres34_bn230419568.gif


GRB_name: GRB230402A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33655
SUBJECT: GRB 230402A: Fermi GBM detection
DATE:    23/04/19 17:35:11 GMT
FROM:    Oliver J Roberts at USRA/NASA <oliver.roberts@nasa.gov>

C. Malacaria (ISSI) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 07:32:35.96 UT on 02 April 2023, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 230402A (trigger 702113560 / 230402314, GCN 33553),
which was also detected by AGILE (GCN 33555), AstroSat CZTI (GCN 33562),
CALET (GCN 33563) and Fermi-LAT (GCN 33650).
The Fermi GBM Final Real-time Localization (GCN 33553) is consistent
with the Fermi-LAT position.

The angle from the Fermi LAT boresight is 24 degrees.

The GBM light curve consists of a main peak
with a duration (T90) of about 63 s (50-300 keV).
The time-averaged spectrum from T0 s to T0+46 s is best fit by
a power law function with an exponential high-energy cutoff.  
The power law index is -0.94 +/- 0.02 and
the cutoff energy, parameterized as Epeak, is 1030 +/- 81 keV.

A Band function fits the spectrum equally well with 
Epeak= 995 +/- 85 keV, alpha = -0.93 +/- 0.02 and beta = -2.9 +/- 0.5 .

The event fluence (10-1000 keV) in this time interval is
(3.99 +/- 0.05)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.3 s in the 10-1000 keV band
is 10.7 +/- 0.3 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"


GRB_name: GRB230418A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33656
SUBJECT: GRB 230418A: AGILE detection
DATE:    23/04/19 20:12:42 GMT
FROM:    Francesco Verrecchia at SSDC,INAF-OAR <francesco.verrecchia@ssdc.asi.it>

G. Panebianco (Univ. Bologna - INAF/OAS Bologna), F. Verrecchia,
C. Pittori (SSDC, and INAF/OAR) , N. Parmiggiani (INAF/OAS-Bologna),
M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), C. Casentini,
A. Argan, M. Cardillo, Y. Evangelista, L. Foffano, E. Menegoni,
G. Piano, A. Ursi (INAF/IAPS), A. Addis, L. Baroncelli, A.
Bulgarelli, A. Di Piano, V. Fioretti (INAF/OAS-Bologna), F.
Lucarelli (SSDC, and INAF/OAR), M. Romani (INAF/OA-Brera), M.
Marisaldi (INAF/OAS-Bologna, and Bergen University), M. Pilia,
A. Trois (INAF/OA-Cagliari), F. Longo (Univ. Trieste and INFN
Trieste), I. Donnarumma (ASI), A. Giuliani (INAF/IASF-Mi), and
P. Tempesta (TeleSpazio), report on behalf of the AGILE Team:

The AGILE satellite detected the GRB 230418A at T0 = 2023-04-18
21:11:33 s (UTC), reported by Fermi GBM (GCNs #33652, #33653).
The burst is clearly visible in the AGILE scientific ratemeters
of the MiniCALorimeter (MCAL; 0.4-100 MeV), and AntiCoincidence
(AC; 50-200 keV) detectors.
The event lasted about 2 s and it released a total number of
1538 counts in the MCAL detector (above a background rate of 1100
Hz), and 7778 counts in the AC detector (above a background rate
of 3659 Hz). The AGILE ratemeters light curves can be found at
http://www.agilescienceapp.it/notices/GRB230418A_AGILE_RM_ND.png .

Additional analysis of AGILE data is in progress.
Automatic MCAL GRB alert Notices can be found at:
https://gcn.gsfc.nasa.gov/agile_mcal.html


GRB_name: GRB230418A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33657
SUBJECT: GRB 230418A: AstroSat CZTI detection
DATE:    23/04/20 05:59:08 GMT
FROM:    Gaurav Waratkar at IIT,Bombay <gauravwaratkar@iitb.ac.in>



P K. Navaneeth (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a short GRB 230418A which was also detected by Fermi (O.J. Roberts, et al., GCN Circ. 33652), Swift/BAT-GUANO (S. Ronchini, et al., GCN Circ. 33653), and AGILE (G. Panebianco, et al., GCN Circ. 33656).

The source was clearly detected in the 20-200 keV energy range. The light curve peaks at 2023-04-18 21:11:33.56 UTC. The measured peak count rate associated with the burst is 2120 (+893, -443) counts/s above the background in the combined data of all quadrants, with a total of 155 (+52, -45) counts. The local mean background count rate was 488 (+18, -38) counts/s. Using cumulative rates, we measure a T90 of 0.20 (+0.16, -0.06) s.

The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range.

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb


GRB_name: GRB230420A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33658
SUBJECT: GRB 230420A: Swift detection of a burst
DATE:    23/04/20 10:36:21 GMT
FROM:    Jamie Kennea at Penn State U <jak51@psu.edu>


N. J. Klingler (GSFC/UMBC/CRESSTII), R. Brivio (INAF-OAB),
R. A. J. Eyles-Ferris (U Leicester), J.D. Gropp (PSU),
J. A. Kennea (PSU), K. L. Page (U Leicester),
T. M. Parsotan (GSFC/UMBC/CRESSTII), C. Salvaggio (INAF-OAB) and
B. Sbarufatti (INAF-OAB) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 10:19:01 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 230420A (trigger=1164980).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 161.013, +32.087 which is 
   RA(J2000) = 10h 44m 03s
   Dec(J2000) = +32d 05' 11"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of about 30 sec.  The peak count rate
was ~800 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 10:20:32.9 UT, 91.8 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source with an enhanced position: RA, Dec 161.04899,
32.10766 which is equivalent to:
   RA(J2000)  = 10h 44m 11.76s
   Dec(J2000) = +32d 06' 27.6"
with an uncertainty of 1.9 arcseconds (radius, 90% containment). This
location is 132 arcseconds from the BAT onboard position, within the
BAT error circle. This position may be improved as more data are
received; the latest position is available at
https://www.swift.ac.uk/sper.  We cannot determine whether the source
is fading at the present time. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (1.71 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 2.1
(+2.19/-1.93) x 10^21 cm^-2 (90% confidence). 

The initial flux in the 2.5 s image was 3.05e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 99 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.017. 

Burst Advocate for this burst is N. J. Klingler (noelklin AT umbc.edu). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)


GRB_name: GRB230418A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33659
SUBJECT: IPN triangulation of GRB 230418A (short)
DATE:    23/04/20 14:30:46 GMT
FROM:    Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>

A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin
on behalf of the HEND/Mars Odyssey team,

D. Svinkin, D. Frederiks, A. Ridnaia, A. Lysenko, and
T. Cline on behalf of the Konus-Wind team,

A. Goldstein, M. S. Briggs, C. Wilson-Hodge,
and E. Burns on behalf of the Fermi GBM team,

E. Bozzo and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,

S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu
on behalf of the Swift-BAT team,

and

W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr,
and A.S. Gardner on on behalf of the GRS-Odyssey GRB team,
report:

The short-duration GRB 230418A
(Fermi-GBM detection: Roberts et al., GCN Circ. 33652;
Swift/BAT-GUANO detection: Ronchini et al., GCN Circ. 33653;
AGILE detection: Panebianco et al., GCN Circ. 33656;
AstroSat-CZTI detection: Navaneeth et al., GCN Circ. 33657)
was detected by Fermi (GBM trigger 703545098), Swift (BAT),
Konus-Wind, INTEGRAL (SPI-ACS), AGILE (MCAL, AC), AstroSat (CZTI),
and Mars-Odyssey (HEND) at about 76293 s UT (21:11:33).
The burst was outside the coded field of view of the BAT.

We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
 ---------------------------------------------
  RA(2000), deg                 Dec(2000), deg
 ---------------------------------------------
 Center:
   43.442 (02h 53m 46s) -20.343 (-20d 20' 36")
 Corners:
   43.565 (02h 54m 16s) -20.460 (-20d 27' 37")
   43.510 (02h 54m 02s) -20.481 (-20d 28' 53")
   43.320 (02h 53m 17s) -20.226 (-20d 13' 34")
   43.375 (02h 53m 30s) -20.205 (-20d 12' 19")
 ---------------------------------------------
The error box area is 61 sq. arcmin, and its maximum
dimension is 20 arcmin (the minimum one is 3.2 arcmin).
The Sun distance was 35 deg.

This box may be improved.

The IPN localization is consistent with, but reduces the area of,
the Fermi-GBM final localization (GCN 33652).

A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB230418_T76289/IPN

The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.


GRB_name: GRB230414B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33660
SUBJECT: GRB230414B: VIRT Optical Upper Limit
DATE:    23/04/20 18:02:52 GMT
FROM:    Priya Gokuldass at Florida Tech <pgokuldass2020@my.fit.edu>

N. Orange (OrangeWave Innovative Science, LLC), K. Smith (UVI), R. Querrard (UVI), H. Zimmerman (UVI), D. Morris (UVI), P. Gokuldass (Florida Tech), and K. Noonan (UVI) report:

We observed the field of GRB230414B (D'Ai et al. GCN 33612; Evans et al. GCN 33613) with the 0.5m Virgin Island Robotic Telescope (VIRT) at the University of the Virgin Islands' Etelman Observatory on 04-16-2023 starting at 01:37:00 UT (T+33.4 hrs). We performed a series of exposures in R filter with a total exposure of 2900 s. The weather conditions were mixed during the hours of observation with an average airmass of ~1.3.

We do not detect the source identified by others (Pankov et al., GCN 33615; Lu et al., GCN 33616; Raman et al., GCN 33618; Ghosh et al., GCN 33620; Moskvitin et al., GCN 33622; Malesani et al., GCN 33623; Zhu et al., GCN 33625; Belkin et al., GCN 33628; Fernandez et al., GCN 33629; Quadri et al., GCN 33630; Leonini et al., GCN 33634; Ror et al., GCN 33636; Querrard et al., GCN 33637; Ruocco, GCN 33641; LaPorte et al., GCN 33642; Risin et al., GCN 33648) and report the following 3-sigma upper limit:

T_mid               ||Exposure     ||Filter      ||Limit
T+35.1 hrs       ||2900s            ||R              ||>20.5

The limit is estimated from comparison to nearby USNO B1 stars and is not corrected for Galactic extinction. The VIRT is still in the
commissioning phase. 

We acknowledge financial support from NASA MUREP MIRO award 80NSSC21M0001, NASA EPSCoR award 80NSSC22M0063, and NSF EiR award 1901296. R.Q. and N.B.O. also acknowledge financial support from South Carolina Space Grant award 80NSSC20M0054. This message can be cited.


GRB_name: GRB230420A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33661
SUBJECT: GRB 230420A: Enhanced Swift-XRT position
DATE:    23/04/20 19:32:25 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 1619 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 230420A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 161.04816, +32.10769 which is equivalent
to:

RA (J2000): 10h 44m 11.56s
Dec (J2000): +32d 06' 27.7"

with an uncertainty of 2.2 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB230420A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33662
SUBJECT: GRB 230420A: LCOGT Optical Upper Limit
DATE:    23/04/20 23:21:17 GMT
FROM:    Robert Strausbaugh at University of Minnesota <rstrausb@umn.edu>

R. Strausbaugh (University of Minnesota), A. Cucchiara (NASA) report on
behalf of a larger collaboration:

We observed the GRB 230420A (Klingler et al., GCN 33658) field with the
LCOGT 1-meter Sinistro instrument at the Teide Observatory, Tenerife site,
on April 20, from 20:28 to 20:55 UT (corresponding to 11.15 to 11.72 hours
from the GRB trigger time) with the SDSS r and i filters.

We performed a series of 3x300s exposures in each band.  We do not detect a
source within the Swift-XRT enhanced error region (Osborne et al., GCN
33661) in either band.

The following upper limits are calculated using the PanSTARRS catalog as
reference:

r > 22.3
i > 21.8

These magnitudes are not corrected for galactic extinction.


GRB_name: GRB230420A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33663
SUBJECT: GRB 230420A: BOOTES-5/JGT optical afterglow detection
DATE:    23/04/21 07:47:36 GMT
FROM:    Youdong HU at IAA-CSIC <huyoudong072@hotmail.com>

Y.-D. Hu, E. Fernandez-Garcia, A. J. Castro-Tirado, I. Perez-Garcia, M.D. Caballero-Garcia, R. Sanchez-Ramirez, S. Guziy (IAA-CSIC), D. Hiriart and W. H. Lee (UNAM), C. J. Perez del Pulgar (UMA) and I. Carrasco (SMA) and I. H. Park (SKKU), on behalf of a larger collaboration, report:

Following the detection of GRB 230420A by Swift (Klingler et al. GCNC 33658), the BOOTES-5/JGT 0.6m robotic telescope at Observatorio Astronomico Nacional in San Pedro Martir (Mexico) automatically observed the GRB location starting on Apr. 20, 10:21:03 UT (~ 122 s after trigger). A series of images in clear filter were gathered. A new optical transient was found within the enhanced Swift/XRT position (Osborne et al. GCNC 33661) for which we measure a magnitude of 17.7 on the initial 10 s exposure frame, which we propose to be the optical afterglow for GRB 230420A.

We thank the staff at Observatorio Astronomico Nacional in San Pedro Martir for their excellent support.


GRB_name: GRB230420A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33664
SUBJECT: GRB 230420A: Gaoyazi/GOT optical upper limit
DATE:    23/04/21 09:07:17 GMT
FROM:    Dong Xu at NAOC/CAS <dxu@nao.cas.cn>

S.Y. Fu,  S.Q. Jiang, X. Liu, T.H. Lu, D Xu (NAOC), Z.P. Zhu (NAOC, HUST), S.W. Luo, M.M. Yang, Z. K. Feng (GYZO, NAOC) report

We observed the field of GRB 230420A detected by Swift (Klingler et al., GCN 33658) with the 0.5-meter Gaoyazi Optical Telescope (GOT) located at Gaoyazi, Xinjiang, China. Observations started at 17:23:51 UT on 2023-04-20, i.e., 0.30 days after the Swift/BAT trigger, and 20 x 180 s images were obtained in the Sloan r filter.

No optical source is detected in our stacked image at the enhanced XRT position (Osborne et al,. GCN 33661), down to a limiting (3-sigma) magnitude of r > 21.6 at 0.32 days post-burst, calibrated with nearby PanSTARRS stars.


GRB_name: GRB230420A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33665
SUBJECT: GRB 230420A: NOT optical afterglow confirmation
DATE:    23/04/21 10:27:21 GMT
FROM:    Dong Xu at NAOC/CAS <dxu@nao.cas.cn>

S.Y. Fu (NAOC), K.E. Heintz (DAWN/NBI), D.B. Malesani (Radboud, DAWN/NBI), D. Xu (NAOC), M. Linares (NTNU & UPC), M. Turchetta (NTNU) report on behalf of a larger collaboration:

We observed the field of GRB 230420A detected by Swift (Klingler et al., GCN 33658) using the 2.56-m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Observations started at 00:31:32 UT on 2023-04-21, i.e., ~14.2 hr after the Swift/BAT trigger, and 3 x 300 s images in the Sloan r-filter and 5 x 200 s images in the Sloan z-filter were obtained, respectively.

We detect an uncatalogued source in the stacked images within the enhanced XRT error circle (Osborne et al., GCN 33661) at coordinates:

R.A. (J2000) = 10:44:11.55
Dec. (J2000) = +32:06:28.34

with an uncertainty of ~0.3 arcsec. The source has m(r) = 23.2 +/- 0.2 (AB) at 14.34 hr post-burst and m(z) = 22.3 +/- 0.2 (AB) at 14.64 hr post-burst, calibrated with nearby field stars from the Pan-STARRS catalog.

This source is likely the same as the one observed by BOOTES-5/JGT (Hu et al., GCN 33663), as both sources lie within the very small XRT error circle. The fading confirms that this source is the optical afterglow of GRB 230420A.


GRB_name: GRB230420A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33666
SUBJECT: GRB 230420A: MITSuME Akeno optical observation
DATE:    23/04/21 11:43:58 GMT
FROM:    Narikazu Higuchi at Tokyo Tech <higuchi@hp.phys.titech.ac.jp>

N. Higuchi, I. Takahashi, M. Sasada, S. Sato, R. Hosokawa, M. Niwano, Y.
Yatsu (Tokyo Tech), K. L. Murata (Kyoto U) and N. Kawai (Riken) report on
behalf of the MITSuME collaboration:

We observed the field of GRB 230420A (N. J. Klingler et al. #33658, J.P.
Osborne et al. #33661,R. Strausbaugh et al. #33662, Y.-D. Hu et al.
#33663, S.Y.
Fu et al. #33664, S.Y. Fu et al. #33665) with the optical three color (g',
Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope Akeno.

The observation with a series of 60 sec exposures started at 2023-04-20
10:23:41 UT (280 seconds after the Swift/BAT detection). We stacked the
images with good conditions. Here we report the Rc and Ic band magnitudes
by the forced-photometry at the enhanced Swift/XRT position (J.P. Osborne
et al. GCN Circular #33661), and the 5-sigma limit of the stacked images in
the g' band.

T0+[sec] |MID-UT | T-EXP[sec] | magnitudes of forced-photometry

------------------------------------------------------------------------------------------------

 588 | 2023-04-20 10:28:49| 540 | g'>18.3, Rc=18.3+/- 0.3, Ic=17.3 +/- 0.2

------------------------------------------------------------------------------------------------

T0+ : Elapsed time after the burst

T-EXP: Total Exposure time

We used PS1 catalog for flux calibration. The magnitudes are expressed in
the AB system. The images were processed in real-time through the MITSuME
GPU reduction pipeline (Niwano et al. 2021, PASJ, Vol.73, Issue 1, Pages
4-24; https://github.com/MNiwano/Eclaire).


GRB_name: GRB230420A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33667
SUBJECT: GRB 230420A: Swift-XRT refined Analysis
DATE:    23/04/21 12:21:34 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

E. Ambrosi  (INAF-IASFPA) , S. Dichiara (PSU), J.A. Kennea (PSU), A.
Tohuvavohu (U. Toronto), A.P. Beardmore (U. Leicester), P.A. Evans (U.
Leicester), J.P. Osborne (U. Leicester), M. Capalbi (INAF-IASFPA), M.
Perri (SSDC & INAF-OAR) and  report on behalf of the Swift-XRT team:

We have analysed 7.2 ks of XRT data for GRB 230420A, from 98 s to 84.8
ks after the  BAT trigger. The data comprise 102 s in Windowed Timing
(WT) mode with the remainder in Photon Counting (PC) mode. 

The light curve can be modelled with an initial power-law decay with an
index of alpha=4.13 (+0.26, -0.18), followed by a break at T+316 s to
an alpha of 0.83 (+0.10, -0.07).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.59 (+/-0.09). The
best-fitting absorption column is  4.6 (+2.5, -2.3) x 10^20 cm^-2, in
excess of the Galactic value of 1.7 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.82 (+0.21, -0.11)
and a best-fitting absorption column consistent with the Galactic
value. The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.5 x 10^-11 (3.6 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.7 (+4.0, -0.0) x 10^20 cm^-2
Galactic foreground: 1.7 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.82 (+0.21, -0.11)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01164980.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB230421A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33668
SUBJECT: GRB 230421A: Fermi GBM Final Real-time Localization
DATE:    23/04/21 13:54:39 GMT
FROM:    William Cleveland at NASA-MSFC <william.cleveland@nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 09:42:46 UT on 21 Apr 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230421A (trigger 703762971.373066 / 230421405).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 44.5, Dec = 6.0 (J2000 degrees, equivalent to J2000 02h 58m, 6d 00'), with a statistical uncertainty of 5.5 degrees.

The angle from the Fermi LAT boresight is 99.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230421405/quicklook/glg_skymap_all_bn230421405.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230421405/quicklook/glg_healpix_all_bn230421405.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230421405/quicklook/glg_lc_medres34_bn230421405.gif


GRB_name: GRB230420A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33670
SUBJECT: GRB 230420A: Swift-BAT refined analysis
DATE:    23/04/21 14:58:39 GMT
FROM:    Tyler Parsotan  at NASA GSFC <tyler.parsotan@nasa.gov>

T. Sakamoto (AGU), S. D. Barthelmy (GSFC),  H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC/UMBC), M. Stamatikos (OSU) (i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 230420A (trigger #1164980) (Klingler, et al., GCN Circ. 33658). The BAT ground-calculated position is
RA, Dec = 161.040, 32.111 deg which is
   RA(J2000)  =  10h 44m 09.5s
   Dec(J2000) = +32d 06' 38.3"
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).The partial coding was 100%.

The mask-weighted light curve shows possible pre-trigger activity with extended emission out to ~100 seconds. T90 (15-350 keV) is 111.75 +- 12.02 sec (estimated error including systematics).

The time-averaged spectrum from T-34.75 to T+100.80 sec is best fit by a power law with an exponential cutoff.  This fit gives a photon index 0.96 +- 0.46,  and Epeak of 70.6 +- 28.2 keV (chi squared 53.29 for 56 d.o.f.).  For this model the total fluence in the 15-150 keV band is 2.7 +- 0.2 x 10^-06 erg/cm2 and the 1-sec peak flux measured from T+1.41 sec in the 15-150 keV band is 1.0 +- 0.2 ph/cm2/sec.  A fit to a simple power law gives a photon index of 1.64 +- 0.10 (chi squared 60.99 for 57 d.o.f.).  All the quoted errors are at the 90% confidence level.

The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/1164980/BA/


GRB_name: GRB230420A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33671
SUBJECT: GRB230420A: VLT optical observation
DATE:    23/04/21 17:10:28 GMT
FROM:    Hallie Fausey at George Washington U <hfausey@gwmail.gwu.edu>

H. Fausey (GWU), B. Schneider (MIT),  C. C. Thoene (ASU-CAS), D. B. Malesani (Radboud Univ. and DAWN/NBI), and S. Campana (INAF-OAB) report on behalf of the Stargate collaboration:

We observed the field of GRB230420A (Klinger et al., GCN33658) with the ESO VLT UT3 (Melipal) using the acquisition camera of the X-shooter spectrograph. We took a 300s r-band image on 2023 April 20.105 UT (16 hours after the BAT trigger).

At the coordinates of the optical afterglow (Hu et al., GCN 33663; Fu et al., GCN 33665), we detect a faint source with magnitude r' = 23.2 +/- 0.1 (AB). The magnitude is consistent, within the errors, to the value reported by Fu et al. (GCN 33665). We note the presence of a marginally-detected object in the Legacy Survey at the same coordinates, which, if real, could be the GRB host galaxy.

We acknowledge the excellent support from the ESO observing staff in Paranal, in particular Zahed Wahhaj.


GRB_name: GRB230421A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33672
SUBJECT: GRB 230421: Swift/BAT-GUANO arcminute localization
DATE:    23/04/21 18:14:17 GMT
FROM:    Aaron Tohuvavohu at University of Toronto <aaron.tohu@gmail.com>

James DeLaunay (U Alabama), Aaron Tohuvavohu (U Toronto), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Samuele Ronchini (PSU), Tyler Parsotan (UMBC/GSFC) report:

Swift/BAT did not localize GRB 230431A onboard (T0: 2023-04-21 09:42:46.370000UTC, Fermi/GBM GCN 33668).

The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). 

Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground.

The burst occured during a Swift slew. 
Slew mosaic imaging finds the position of the burst with SNR of 10.5.

The BAT position is
RA, Dec = 41.704, +1.119 deg which is
   RA(J2000)  = 02h 46m 48.96s
   Dec(J2000) = +01d 07â€² 08.4â€³
with an estimated uncertainty of 5 arcmin radius.

The burst location is Sun constrained for Swift, so there will be no XRT or UVOT followup.

GUANO is a fully autonomous, extremely low latency, spacecraft
commanding pipeline designed for targeted recovery of BAT event mode
data around the times of compelling astrophysical events to enable
more sensitive GRB searches.

A live reporting of Swift/BAT event data recovered by GUANO can be
found at: https://www.swift.psu.edu/guano/


GRB_name: GRB230420A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33673
SUBJECT: GRB 230420A: Swift/UVOT Upper Limits
DATE:    23/04/21 20:14:30 GMT
FROM:    Samantha Oates at University of Birmingham <samantha.oates@alumni.ucl.ac.uk>

S. R. Oates (U.Birmingham) and N. J. Klingler (GSFC/UMBC/CRESSTII)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 230420A
99 s after the BAT trigger (Klingler et al., GCN Circ. 33658).
No optical afterglow consistent with the XRT position
(Osborne et al., GCN Circ. 33661) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC            99          249          147         >21.1
u_FC               258          508          246         >20.5
white               99         1190          353         >21.7
v                  590         4885          255         >19.5
b                  514         1165           58         >19.9
u                  258         1141          285         >20.6
w1                 814         5109           52         >19.1
w2                4481         4681          197         >19.8

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.017 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB230418A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33674
SUBJECT: Konus-Wind detection of GRB 230418A
DATE:    23/04/22 16:32:46 GMT
FROM:    Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>

D. Svinkin, D. Frederiks, M. Ulanov, A. Tsvetkova,
A. Lysenko, A. Ridnaia, and T. Cline
on behalf of the Konus-Wind team, report:

The short-duration GRB 230418A
(Fermi-GBM detection: Roberts et al., GCN Circ. 33652;
Swift/BAT-GUANO detection: Ronchini et al., GCN Circ. 33653;
AGILE detection: Panebianco et al., GCN Circ. 33656;
AstroSat-CZTI detection: Navaneeth et al., GCN Circ. 33657;
IPN triangulation: Kozyrev et al., GCN Circ. 33659)
triggered Konus-Wind at T0=76289.941 s UT (21:11:29.941).

The burst light curve shows a multi-peaked structure
which starts at ~T0 s and has a total duration of ~0.3 s.
The emission is seen up to ~2 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB230418_T76289/

As observed by Konus-Wind, the burst
had a fluence of 4.13(-0.64,+0.76)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0+0.048 s,
of 3.84(-1.00,+1.10)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+0.192 s)
is best fit in the 20 keV - 2 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.52(-0.20,+0.23)
and Ep = 1071(-228,+335) keV (chi2 = 16/24 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -1.87
(chi2 = 16/23 dof).

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB230421A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33675
SUBJECT: GRB 230421A: Fermi GBM observation
DATE:    23/04/22 18:20:58 GMT
FROM:    Oliver J Roberts at USRA/NASA <oliver.roberts@nasa.gov>

E. Bissaldi (Politecnico and INFN Bari) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 09:42:46.37 UT on 21 April 2023, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 230421A (trigger 703762971 / 230421405),
which was also detected by the Swift/BAT-GUANO (DeLaunay et al. 2023, GCN 33672).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight
at the GBM trigger time is 104 degrees.

The GBM light curve consists of a single emission episode
with a duration (T90) of about 10 s (50-300 keV).
The time-averaged spectrum from T0-1 s to T0+4 s is
adequately fit by a power law function with an exponential
high-energy cutoff. The power law index is -1.1 +/- 0.2 and
the cutoff energy, parameterized as Epeak, is 360 +/- 160 keV.

The event fluence (10-1000 keV) in this time interval is
(1.3 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-0.3 s in the 10-1000 keV band
is 3.2 +/- 0.3 ph/s/cm^2.


The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"


GRB_name: GRB221009A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33676
SUBJECT: GRB 221009A: Late-time JWST Observations and Detection of Supernova Emission
DATE:    23/04/23 02:40:59 GMT
FROM:    Peter K. Blanchard at Northwestern University <peter.blanchard@northwestern.edu>

P. K. Blanchard (Northwestern/CIERA), V. A. Villar (PSU), R. Chornock (UC Berkeley), H. Sears (Northwestern/CIERA), N. LeBaron (UC Berkeley), S. K. Yadavalli (PSU), T. Laskar (Utah), K. D. Alexander (Arizona), R. Margutti (UC Berkeley), E. Berger (Harvard/CfA), J. Barnes (UCSB), D. Siegel (U. Guelph/Perimeter), B. Metzger (Columbia and Flatiron/CCA), D. Kasen (UC Berkeley), Y. Cendes (Harvard/CfA), T. Eftekhari (Northwestern/CIERA), and J. Leja (PSU) report:

We obtained spectra at the position of the afterglow of GRB 221009A (Dichiara et al., GCN 32632; Lipunov et al., GCN 32634; Kennea & Williams, GCN 32635; Veres et al., GCN 32636; Bissaldi et al., GCN 32637) with JWST/NIRSpec under DDT program 2784 (P.I. Blanchard) starting at 2023 April 20 14:40 UT (193 observer-frame days after the burst). The spectra were taken with the G140M/F100LP and G235M/F170LP grating/filter combinations with an exposure time of 11,015 seconds in each setup. This yields a total wavelength coverage of about 1 - 3 microns.

We correct our combined G140M+G235M spectrum for Galactic extinction using the fitted extinction parameters found by Levan et al., ApJL, 946, L28 (2023). The spectrum significantly differs from a power-law continuum observed 13 days after the burst (observer frame; Levan et al., GCN 32821). This suggests that there is now significant contribution from the SN/host galaxy. We detect a broad emission line feature centered at ~1 micron (observer frame) consistent with the Ca II IR triplet from a SN, and prominent narrow, host galaxy emission lines. If confirmed by further analysis, this would represent the first identification of specific SN spectral features associated with GRB 221009A.

Further analysis is ongoing.

We thank STScI staff members Crystal Mannfolk, Leonardo Ubeda, Armin Rest and the entire JWST team for the successful implementation of this DDT program.


GRB_name: GRB230423A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33677
SUBJECT: Swift Trigger 1165354 is probably not a GRB
DATE:    23/04/23 19:40:27 GMT
FROM:    David Palmer at LANL <palmer@lanl.gov>


R. Brivio (INAF-OAB), J.D. Gropp (PSU), J. A. Kennea (PSU),
N. J. Klingler (GSFC/UMBC/CRESSTII), N. P. M. Kuin (UCL-MSSL),
S. Laha (GSFC/UMBC), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL),
C. Salvaggio (INAF-OAB) and T. Sbarrato (INAF-OAB) report on behalf of
the Neil Gehrels Swift Observatory Team:

At 19:07:55 UT, the Swift Burst Alert Telescope (BAT) triggered and located
a marginal image peak, which is possibly GRB 230423A (trigger=1165354). 
Swift slewed immediately to the image location. 
The BAT on-board calculated location is 
RA, Dec 122.605, -21.920 which is 
   RA(J2000) = 08h 10m 25s
   Dec(J2000) = -21d 55' 12"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of about 30 sec.  The peak count rate
was ~600 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 19:09:36.5 UT, 101.1 seconds after
the BAT trigger. No source was detected in 777 s of promptly downlinked
data. We are waiting for the full dataset to detect and localise the
XRT counterpart. 

UVOT took a finding chart exposure of 150 seconds with the White 
filter  starting 885 seconds after the BAT trigger. No credible 
afterglow candidate has  been found in the initial data products. The 
2.7'x2.7' covers 25% of the BAT error circle. The typical 3-sigma
upper limit has been about 19.6 mag. The 8'x8'  region for  the list
of sources generated on-board covers 100% of the BAT error  circle. No
correction has been made for the expected extinction   corresponding
to E(B-V) of 0.136. 

Due to the marginal significance (7.3 sigma) of this detection in BAT
and the lack of an observed XRT counterpart, we cannot confirm
that this is a real GRB.  However, the XRT observation was
interrupted by entry into the South Atlantic Anomaly (SAA)
so the bulk of the XRT exposure time may have been after
any source could have faded significantly.  For this reason,
we will not be able to verify or refute the reality of this
detection until the full dataset is downloaded. 


GRB_name: GRB230423A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33679
SUBJECT: GRB 230423A: Swift-XRT afterglow detection
DATE:    23/04/24 14:11:56 GMT
FROM:    Chiara Salvaggio at INAF OABrera <chiara.salvaggio@inaf.it>

C. Salvaggio (INAF-OAB), P. Dâ€™avanzo (INAF-OAB), T. Sbarrato (INAF-OAB), R.
Brivio (INAF-OAB), M. Ferro (INAF-OAB), M.G. Bernardini (INAF-OAB), A. Y.
Lien (U Tampa), K.L. Page (U. Leicester), P.A. Evans (U. Leicester) report
on behalf of the Swift-XRT team:


We have analysed 852s of Swift/XRT data for GRB 230423A (R.Brivio et al.,
GCN CIrc. 33677), from t-t0=704.5 s to t+t0=4893.3 s after the BAT trigger
1165354. The trigger was previously indicated as non-burst due to a low BAT
significance detection and the absence of an XRT counterpart (GCN circ.
33677).

We found an uncatalogued fading source with coordinates:

RA (J2000): 08h 10m 19.94s

DEC (J2000): -21d 55â€™ 33.5â€

with an uncertainty of 3.8â€ (radius, 90% confidence).

We propose this source as the X-ray afterglow of GRB 230423A.


The results of the XRT-team automatic analysis are available at

https://www.swift.ac.uk/xrt_products/01165354


This circular is an official product of the Swift-XRT team


GRB_name: GRB230420A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33680
SUBJECT: GRB 230420A: Lowell Discovery Telescope Optical Detection
DATE:    23/04/24 17:00:41 GMT
FROM:    Brendan O'Connor at UMD <oconnorb@umd.edu>

B. O'Connor (UMD, GWU), E. Hammerstein (UMD), S.B. Cenko (UMD, NASA-GSFC), report on behalf of a larger collaboration:

We observed GRB 230420A (Klingler et al. GCN 33658) with the Large Monolithic Imager (LMI) on the 4.3m Lowell Discovery Telescope (LDT). Observations began on 2023-04-23 at 05:14:37 UT corresponding to ~2.8 d after the GRB trigger. Observations were carried out in r-band and i-band for 1800 s each at airmass 1.05 under seeing of ~1.6".

At the location of the optical counterpart (Hu et al. GCN 33663, Fu et al. GCN 33665, Fausey et al. GCN 33671) we detect a weak source in each filter. We measure magnitudes r~25.0+/-0.4 AB mag and i~24.2+/-0.2 AB mag. This is likely dominated by the contribution from the possible host galaxy  (Fausey et al. GCN 33671).

Magnitudes are calibrated against the PS1 catalog and are not corrected for Galactic extinction.

We thank the staff of the Lowell Discovery Telescope for assistance with these observations.


GRB_name: GRB230423A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33681
SUBJECT: GRB 230423A: Swift-XRT refined Analysis
DATE:    23/04/25 04:27:05 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), D.N. Burrows (PSU), P.A.
Evans (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester), M. Capalbi (INAF-IASFPA), M. Perri (SSDC & INAF-OAR), V.
D'Elia (SSDC & INAF-OAR) and  report on behalf of the Swift-XRT team:

We have analysed 2.5 ks of XRT data for GRB 230423A, from 680 s to 57.3
ks after the  BAT trigger. The data comprise 22 s in Windowed Timing
(WT) mode with the remainder in Photon Counting (PC) mode. The refined
XRT position is RA, Dec = 122.5830, -21.9259 which is equivalent to:

RA (J2000): 08 10 19.91
Dec(J2000): -21 55 33.1

with an uncertainty of 3.7 arcsec (radius, 90% confidence).

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.19 (+0.39, -0.28).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.6 (+/-0.8). The
best-fitting absorption column is  3.3 (+1.5, -1.3) x 10^22 cm^-2, in
excess of the Galactic value of 2.0 x 10^21 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 5.9 x 10^-11 (2.8 x 10^-10) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      3.3 (+1.5, -1.3) x 10^22 cm^-2
Galactic foreground: 2.0 x 10^21 cm^-2
Excess significance: 4.1 sigma
Photon index:      2.6 (+/-0.8)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01165354.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB230425A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33682
SUBJECT: GRB 230425A: Fermi GBM Final Real-time Localization
DATE:    23/04/25 14:30:19 GMT
FROM:    Joe Mangan at IJCLab <joseph.mangan@ijclab.in2p3.fr>

The Fermi GBM team reports the detection of a likely SHORT GRB

At 05:30:39 UT on 25 Apr 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230425A (trigger 704093444 / 230425230).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 150.7 Dec = -33.9 (J2000 degrees, equivalent to J2000 10h 02m, 33d 54'), with a statistical uncertainty of 11.5 degrees.

The angle from the Fermi LAT boresight is 74 degrees.

The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230425230/quicklook/glg_skymap_all_bn230425230.png

The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230425230/quicklook/glg_healpix_all_bn230425230.fit

The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230425230/quicklook/glg_lc_medres34_bn230425230.gif


GRB_name: GRB230423A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33683
SUBJECT: GRB 230423A: Swift/UVOT Upper Limits
DATE:    23/04/25 20:34:48 GMT
FROM:    Paul Kuin at MSSL <npkuin@gmail.com>

N. Paul Kuin (UCL-MSSL) and Riccardo Brivio (INAF-OAB)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 230423A
731 s after the BAT trigger (Brivio et al., GCN Circ. 33677).  No optical
afterglow consistent with the XRT position  Salvaggio et al., GCN
Circulars 33679,  is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC           731          881          147         >20.9
white              731         5415          491         >21.4
b                 5010         5210          197         >20.0
u                 4805         5004          197         >19.2
w2                5420         5544          122         >19.5

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.137 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB230426A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33684
SUBJECT: GRB 230426A: Fermi GBM Final Real-time Localization
DATE:    23/04/26 20:39:19 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 20:28:59 UT on 26 Apr 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230426A (trigger 704233744.96626 / 230426853).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 38.5, Dec = -82.4 (J2000 degrees, equivalent to J2000 02h 34m, -82d 24'), with a statistical uncertainty of 1.0 degrees.

The angle from the Fermi LAT boresight is 49.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230426853/quicklook/glg_skymap_all_bn230426853.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230426853/quicklook/glg_healpix_all_bn230426853.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230426853/quicklook/glg_lc_medres34_bn230426853.gif


GRB_name: GRB230426A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33686
SUBJECT: GRB 230426A: AstroSat CZTI detection
DATE:    23/04/27 05:36:14 GMT
FROM:    Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>



P K. Navaneeth (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data with the ML pipeline (Abraham et al., 2021, MNRAS, 504, 3084) and the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a bright long GRB 230426A which was also detected by Fermi (Fermi GBM Team, GCN Circ. 33684).

The source was clearly detected in the 20-200 keV energy range. The light curve peaks at 2023-04-26 20:29:23.50 UTC. The measured peak count rate associated with the burst is 1773 (+77, -81) counts/s above the background in the combined data of all quadrants, with a total of 14876 (+653, -615) counts. The local mean background count rate was 454 (+2, -3) counts/s. Using cumulative rates, we measure a T90 of 23 (+3, -2) s. In the preliminary analysis, we find 1069 Compton events associated with this event.

The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2023-04-26 20:29:23.50 UTC. The measured peak count rate associated with the burst is 1179 (+82, -77) counts/s above the background in the combined data of all quadrants, with a total of 8609 (+655, -665) counts. The local mean background count rate was 1491 (+4, -5) counts/s. We measure a T90 of 18 (+5, -2) s from the cumulative Veto light curve.

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb


GRB_name: GRB230427A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33687
SUBJECT: GRB 230427A: Swift detection of a burst with an optical counterpart
DATE:    23/04/27 10:51:55 GMT
FROM:    K.L. Page at U Leicester <klp5@leicester.ac.uk>


E. Troja (UToV), P. A. Evans (U Leicester),
R. A. J. Eyles-Ferris (U Leicester), C. Gronwall (PSU),
J.D. Gropp (PSU), J. A. Kennea (PSU) and K. L. Page (U Leicester)
report on behalf of the Neil Gehrels Swift Observatory Team:

At 10:31:52 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 230427A (trigger=1165948).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 153.324, +48.180 which is 
   RA(J2000) = 10h 13m 18s
   Dec(J2000) = +48d 10' 48"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  No BAT light-curve is available at this time. 

The XRT began observing the field at 10:33:25.9 UT, 94.0 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source with an enhanced position: RA, Dec 153.31199,
48.20404 which is equivalent to:
   RA(J2000)  = 10h 13m 14.88s
   Dec(J2000) = +48d 12' 14.6"
with an uncertainty of 1.9 arcseconds (radius, 90% containment). This
location is 91 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at https://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (8.35 x
10^19 cm^-2, Willingale et al. 2013), with an excess column of 3.5
(+2.81/-2.63) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 98 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  = 10:13:15.05 = 153.31270
  DEC(J2000) = +48:12:14.4  =  48.20400
with a 90%-confidence error radius of about 0.74 arc sec. This position is 1.4
arc sec. from the center of the XRT error circle. The estimated magnitude is
20.31 with a 1-sigma error of about  0.20. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.007. 

Burst Advocate for this burst is E. Troja (nora.gsfc AT gmail.com). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)


GRB_name: GRB230427A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33688
SUBJECT: GRB 230427A: Enhanced Swift-XRT position
DATE:    23/04/27 13:41:28 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 1112 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 230427A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 153.31316, +48.20393 which is equivalent
to:

RA (J2000): 10h 13m 15.16s
Dec (J2000): +48d 12' 14.2"

with an uncertainty of 2.4 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB230426A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33689
SUBJECT: GRB 230426A: Fermi GBM Detection
DATE:    23/04/27 15:03:34 GMT
FROM:    Joshua Wood at NASA/MSFC <joshua.r.wood@nasa.gov>

J. Wood (NASA/MSFC) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 20:28:59.97 UT on 26 April 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230426A (trigger 704233744/230426853)
which was also detected by AstroSat CZTI (P K. Navaneeth et al. 2023, GCN 33686).

The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 38.53, Dec = -82.40 (J2000 degrees, equivalent to
J2000 2h 34m, -82d 24'), with a statistical uncertainty of 1.00 degrees.
(radius, 1-sigma containment, statistical only; there is additionally a
systematic error which we have characterized as a mixture of two Gaussians,
one with a radius of 1.8 degrees (52% contribution) and one with a radius
of 4.1 degrees (47% contribution) [A. Goldstein et al. 2020, ApJ, 895, 1]).

The angle from the Fermi LAT boresight is 49 degrees.

The GBM light curve consists of multiple pulses with a duration (T90)
of about 25.9 s (50-300 keV). The time-averaged spectrum
from T0+8.2 to T0+35.8 s is best fit by
a Band function with Epeak = 77 +/- 2 keV,
alpha = -1.34 +/- 0.02, and beta = -2.38 +/- 0.03.

The event fluence (10-1000 keV) in this time interval is
(5.21 +/- 0.04)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+23 s in the 10-1000 keV band is 66.6 +/- 0.7 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"


GRB_name: GRB230427A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33690
SUBJECT: GRB 230427A: MITSuME Akeno optical upper limits
DATE:    23/04/27 15:34:00 GMT
FROM:    Ichiro Takahashi at Tokyo Tech <itakahashi@hp.phys.titech.ac.jp>

I. Takahashi, S. Hayatsu, N. Higuchi, M. Sasada, R. Hosokawa, S. Sato,
M. Niwano, H. Seki, H. Takei, Y. Yatsu (Tokyo Tech), K. L. Murata
(Kyoto U) and N. Kawai (Riken) report on behalf of the MITSuME
collaboration:

We observed the field of GRB 230427A (Troja et al. GCN Circular
#33687, Beardmore et al. GCN Circular #33688) with the optical three
color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm
telescope Akeno.

The observation started at 2023-04-27 10:33:23 UT (91 seconds after
the Swift/BAT trigger). We stacked the images with good conditions. We
did not detect any uncatalogued sources within the error region (Troja
et al. GCN Circular #33687). We obtained the 5-sigma limits of the
stacked images as follows.

T0+[sec] | MID-UT | T-EXP[sec] | 5-sigma limits
------------------------------------------------------------------------------------------------
263 | 2023-04-27 10:36:15 | 160.0 | g'>17.8, Rc>17.4, Ic>17.0
753 | 2023-04-27 10:44:25 | 540.0 | g'>18.7, Rc>18.7, Ic>18.2
2391 | 2023-04-27 11:11:43 | 2220.0 | g'>19.6, Rc>19.4, Ic>19.0
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time

We used the PS1 catalog for flux calibration. The magnitudes are
expressed in the AB system. The images were processed in real-time
through the MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ,
Vol.73, Issue 1, Pages 4-24; https://github.com/MNiwano/Eclaire).


GRB_name: GRB230426A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33691
SUBJECT: GRB 230426A: MASTER OT J023135.16-792104.8 optical counterpart discovery
DATE:    23/04/27 17:28:36 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>


V.Lipunov (Lomonosov MSU), D.A.H.Buckley (SAAO), Ya.Kechin, A.Chasovnikov,
A.Kuznetsov, N.Tiurina, P.Balanutsa, O.Gress, E.Gorbovskoy, G.Antipov, K.Zhirkov, D.Vlasenko,
V.Senik, V.Topolev, Yu.Tselik, Siyu Wu (Lomonosov Moscow State University, SAI, Physics Department),
C.Francile, F. Podesta, C.Lopez, R. Podesta (Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.Corella,
L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory),
N.M.Budnev, O.Ershova (ISU,API),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational State University),
K.Vetrov, V.Shumkov, T.Pogrosheva

MASTER-SAAO robotic telescope (Global MASTER Net  http://observ.pereplet.ru,Lipunov et al., 2010, Advances in Astronomy, v.2010, 30L)
located in South African Astronomical Observatory
started (Lipunov et al. GCN 33685) inspect of the FERMI GRB230426.85 (trigger 704233744, Wood et al. GCN 33689, Ttrigger 20:28:59.97UT) errorbox
4359 sec after notice time (4391 sec after trigger time) at 2023-04-26 21:42:11UT with upper limit up to 19.5m,
see our cover map https://master.sai.msu.ru/site/master2/observ.php?id=2212931

MASTER OT J023135.16-792104.8 - optical counterpart of GRB 230426A discovery
2023gwu

MASTER-SAAO auto-detection system found optical counterpart of GRB 230426.85
at R.A.,Dec(2000) = 02h 31m 35.16s , -79d 21m 04s.8 with unfiltered m_OT=17.4 at
2023-04-26 21:56:50UT and with optical decay at 10 images
 https://www.wis-tns.org/object/2023gwu .

There is no any sources in VIZIER database, no any objects in MPC at this time
and no OT in MASTER database since Dec.2014. We used reference image on
2018-08-18.99148 UT with  unfiltered mlim=20.6m.

Analysis will be continued.

Deep photometry and spectral observations are required.

The message may be cited.


GRB_name: GRB230427A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33693
SUBJECT: GRB 230427A: AKO Upper Limit
DATE:    23/04/27 19:23:20 GMT
FROM:    Mohammad Odeh at Al Khatim Observatory M44 <mshodeh@gmail.com>

Mohammad Odeh of Al-Khatim Observatory (AKO) operated by the International
Astronomical Center, in Abu Dhabi, UAE.



As a follow-up for the GRB 230427A detected by Swift (GCN 33687), we
observed the field of the GRB with our 0.35m f/7.7 robotic telescope. The
observation was done on 27 April 2023 from 16:06:55 to 16:13:01 (UT), 5.7
hours after the GRB trigger. We obtained multiple 180-sec exposures in Ic
filter. We did not detect any afterglow within XRT localization. This is
consistent with the report of (Takahashi et al., GCN 33690) and (Lipunov et
al., GCN 33692).



The following upper limit was calculated using Atlas catalogue as a
reference:

-----------------------------------------------------------------------------

JD (mid), T_mid-T0(hrs), Exposure (sec), Filter, Lim_mag

-----------------------------------------------------------------------------

2460062.174630, 5.7, 3 x 180 (stacked), Ic, > 19.0

-----------------------------------------------------------------------------



These magnitudes are not corrected for galactic extinction.


GRB_name: GRB230423A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33694
SUBJECT: GRB 230423A(trigger #1165354): Swift-BAT refined analysis
DATE:    23/04/27 21:21:35 GMT
FROM:    Sibasish Laha at GSFC <sibasish.laha@nasa.gov>

T. Sakamoto (AGU), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Parsotan (GSFC/UMBC),
M. Stamatikos (OSU)(i.e. the Swift-BAT team):



Using the data set from T-240 to T+962 sec from the recent telemetry downlink,
we have found that BAT trigger #1165354 is a GRB 230423A even though
the original GCN Circular (Brivio et al., GCN Circ. 33677) based on the immediately
available data suggested that it was probably a statistical fluctuation.
 The BAT ground-calculated position is
RA, Dec = 122.618, -21.901 deg which is
   RA(J2000)  =  08h 10m 28.2s
   Dec(J2000) = -21d 54' 03.6"
with an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.

The BAT light curve showed a complex structure with a duration of about 30 sec.
T90 (15-350 keV) is 23.60 +- 4.27 sec (estimated error including systematics).

The time-averaged spectrum from T-2.25 to T+24.49 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.69 +- 0.27.  The fluence in the 15-150 keV band is 4.6 +- 0.8 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T+10.62 sec in the 15-150 keV band
is 0.6 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1165354/BA/


GRB_name: GRB230427A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33695
SUBJECT: GRB 230427A: BOOTES-5/JGT afterglow detection
DATE:    23/04/27 22:44:56 GMT
FROM:    Youdong HU at IAA-CSIC <huyoudong072@hotmail.com>

Y.-D. Hu, E. Fernandez-Garcia, A. J. Castro-Tirado, I. Perez-Garcia, M.D. Caballero-Garcia, R. Sanchez-Ramirez, S. Guziy (IAA-CSIC), D. Hiriart and W. H. Lee (UNAM), C. J. Perez del Pulgar (UMA) and I. M. Carrasco-Garcia (SMA) and I. H. Park (SKKU), on behalf of a larger collaboration, report:

Following the detection of GRB 230427A by Swift (Troja et al. GCNC 33687), the BOOTES-5/JGT 0.6m robotic telescope at observatorio Astronomico Nacional in San Pedro Martir (Mexico) automatically observed the GRB location starting on Apr. 27, 10:35:34 UT (~ 282 s after trigger). A series of images in clear filter were gathered. A new optical transient was found within the enhanced Swift/XRT position (Beardmore et al. GCNC 33688) for which we measure a magnitude of 20.6 +- 0.2 on the co-added 10 s x 54 image, which is consistent with the detection of Swfit/UVOT (Troja et al. GCNC 33687).

We thank the staff at Observatorio Astronomico Nacional in San Pedro Martir for their excellent support.


GRB_name: GRB230427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33696
SUBJECT: GRB 230427A : OHP/T193 optical upper limit
DATE:    23/04/27 23:52:46 GMT
FROM:    Damien Turpin at CEA-Saclay <dturpin-astro@hotmail.com>

D. Turpin (CEA Paris-Saclay), C. Adami (LAM), B. Schneider (MIT),
S. Basa (LAM),  E. Le Floc'h, D. Turpin, D. GÃ¶tz (CEA Paris-Saclay), 
S. D. Vergani (GEPI, Obs. de Paris), report on behalf 
of a larger collaboration:

We observed the field of GRB 230427A (Troja et al., GCN 33687) 
using the T193cm telescope at Observatoire de Haute-Provence (France) 
equipped with the MISTRAL spectro-imager. 18 exposures were obtained 
in the r-band (16x300s + 2x60s) from 2023 27 April 20:36:47 UT to 
2023 27 April 22:59:06 UT (mid time ~11.27h after trigger). In the combined 
frame, we do not detect any source at the UVOT position reported by 
Troja et al., GCN 33687 and the enhanced XRT position (Beardmore et al.,
GCN 33688) down to the following 3-sigma limit:

r > 22.3 mag (AB)

The photometric calibration was performed using nearby stars from 
the PanSTARRS catalog and the magnitude is not corrected for Galactic 
extinction.

We acknowledge the excellent support from Observatoire de Haute-Provence, 
in particular Jean Balcaen.


GRB_name: GRB230427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33697
SUBJECT: GRB 230427A: GMG upper limit
DATE:    23/04/28 03:50:39 GMT
FROM:    Jirong Mao at Yunnan Obs <jirongmao@mail.ynao.ac.cn>

J. Mao, H.-C. Feng, and J.-M. Bai (YNAO) report:

We observed the field of GRB 230427A (Troja et al. GCN 33687) by the GMG telescope in Yunnan observatories.
The observation began from UT 14:52:28 April 27, 2023, about 4.3 hours from the trigger. We could not observe the optical
afterglow down to a magnitude limit of R~20.6.


GRB_name: GRB230427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33698
SUBJECT: GRB  230427A: Bassano Bresciano Observatory upper limit
DATE:    23/04/28 08:19:17 GMT
FROM:    Ulisse Quadri at Bassano Bresciano Obs <oabb@ulisse.bs.it>

U.Quadri and  L.Strabla (Bassano Bresciano Astronomical Observatory),
in a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan), 
Y. Niino (Tokyo University, Institute of Astronomy), 
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Universita' degli Studi Di Salerno)
report: 

We imaged the field of GRB 230427A detected by SWIFT(trigger 1165948)
with the robotic telescope of (IAU station 565) Bassano Bresciano 
Observatory, Italy. Member of: 
AAVSO - American Association of Variable Star Observers.
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili.
GAC - Gruppo Astrofili Cremonesi.

The observations started 8.72 hour after the GRB trigger, at the end of twilight, 
with our Newton telescope D=250 mm F/D=4.8.

Weather conditions were good.

We co-added 2 series of 25 exposures of 60 sec each.

Start T0+      End T0+      Rlim
8.72 hour     9.63 hour     19.5

We did not found any optical counterpart in the error box of the XRTcandidate.
Troja et al., GCN 33687

Magnitudes were estimated with the USNO-B1.0 cat. and 
are not corrected for galactic dust extinction.

Reference:
http://www.osservatoriobassano.org/GRB.asp

The message may be cited.


GRB_name: GRB230427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33699
SUBJECT: GRB 230427A: GIT optical upper limit
DATE:    23/04/28 09:16:24 GMT
FROM:    Harsh Kumar at Indian Inst of Tech,Bombay <harshkosli13@gmail.com>

T. Roychowdhury(IITB), V. Swain (IITB), A. Suresh (IITB), H. Kumar(IITB),
D. Raman(IITB), Kaysang (IAO), V. Bhalerao(IITB), G. C. Anupama(IIA), S.
Barway(IIA) report on behalf of the GIT team:

We observed GRB 230427A detected by Swift-BAT (Troja et al., GCN 33687)
with 0.7m GROWTH-India Telescope (GIT). The observations started at
14:20:43 UT on 2023-04-27, 3.8 hours after the Swift-BAT trigger. We
obtained 10 images of 300-sec exposures in the r' filter and 5 images of
300-sec exposures in the i', z' and g' filters. We did not detect any new
source in our stacked image within the 2.4 arcsec circle, around R.A.= 10h
13m 15.16s, DEC.=+48d 12' 14.2". The obtained upper limits follow as:

â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”
â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”

JD (mid)  |  T_mid-T0(hrs)  |  Exposure (sec)  |  Filter |  Lim_mag
(5-sigma) |

â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”
â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”

2460062.1148169  |  4.22  |  10 x 300 (stacked)  |  r' | > 21.70  |

2460062.1433660 |  4.91  |  5 x 300 (stacked) |  i' | > 20.76  |

2460062.1604599 |  5.31 |  5 x 300 (stacked) | z' | > 19.42  |

2460062.1775733  |  5.73  |  5 x 300 (stacked) | g' | > 21.35  |

â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”
â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”

Our results are consistent with the upper limit reported by AKO (M. Odeh,
GCN #33693), BOOTES-5/JGT (Y.-D. Hu et al., GCN #33695), OHP/T193 (D.
Turpin et al., GCN #33696), GMG (J. Mao et al., GCN #33697) and Bassano
Bresciano Observatory (U.Quadri et al., GCN #33698). The magnitudes are
calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected
for Galactic extinction.

The GROWTH India Telescope (GIT, Kumar et al. 2022) is a 70-cm telescope
with a 0.7-degree field of view, set up by the Indian Institute of
Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB)
with funding from DST-SERB and IUSSTF. It is located at the Indian
Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding
by the IITB alumni batch of 1994, which partially supports the operations
of the telescope. Telescope technical details are available at
https://sites.google.com/view/growthindia/.


GRB_name: GRB230428A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33700
SUBJECT: GRB 230428A: Fermi GBM Final Real-time Localization
DATE:    23/04/28 09:19:35 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 09:08:58 UT on 28 Apr 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230428A (trigger 704365743.150826 / 230428381).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 121.8, Dec = -86.1 (J2000 degrees, equivalent to J2000 08h 07m, -86d 05'), with a statistical uncertainty of 15.9 degrees.

The angle from the Fermi LAT boresight is 30.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230428381/quicklook/glg_skymap_all_bn230428381.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230428381/quicklook/glg_healpix_all_bn230428381.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230428381/quicklook/glg_lc_medres34_bn230428381.gif


GRB_name: GRB230426A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33702
SUBJECT: GRB 230426A: VZLUSAT-2 detection
DATE:    23/04/28 10:57:54 GMT
FROM:    Marianna DafÄÃ­kovÃ¡ at Masaryk University <500025@mail.muni.cz>

M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory),  N. Werner  (Masaryk U.), M. Ohno (Hiroshima U.),  L. Meszaros, B. Csak (Konkoly Observatory), H. Takahashi (Hiroshima U.), F. Munz , M. Topinka, F. Hroch, N. Husarikova, J.-P. Breuer (Masaryk U.), J. Hudec, J. Kapus, M. Frajt, M. Rezenov (Spacemanic s.r.o), R. Laszlo (Needronix), G. Galgoczi (Wigner Research Center/Eotvos U.), N. Uchida (ISAS/JAXA), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), Y. Fukazawa, K. Hirose, H. Matake (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), L. L. Kiss (Konkoly Observatory),  T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), K. Torigoe (Hiroshima U.), P. Svoboda, V. Daniel, J. Dudas, M. Junas, J. Gromes (VZLU), I. Vertat (FEL ZCU)  -- the VZLUSAT-2/GRB payload collaboration.

The long duration GRB 230426A (Fermi/GBM detection: GCN 33684; Astrosat/CZTI detection: GCN 33686; INTGERAL/SPI-ACS detection at 2023-04-26 20:29:23 UT) was detected by the GRB detectors on board of the VZLUSAT-2 3U CubeSat (https://www.vzlusat2.cz/en/).

The data acquisition was performed by the GRB detector units no. 0 and no. 1. The detection was confirmed at the peak time 2023-04-26 20:29:21 UTC. The T90 duration measured by VZLUSAT-2 is 35 s (25 s) and the significance during T90 reaches 18 sigma (68 sigma) for detector unit no. 0 (no. 1).

The light curve obtained by VZLUSAT-2 is available here:
https://vzlusat2.konkoly.hu/static/share/GRB230426A_GCN_VZLUSAT2.pdf

All VZLUSAT-2 detections are listed at: https://monoceros.physics.muni.cz/hea/VZLUSAT-2/
The GRB detectors on VZLUSAT-2 are a demonstration payload for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). Two GRB modules of VZLUSAT-2 are placed in a perpendicular manner and each consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~30 keV to ~1000 keV. VZLUSAT-2 was launched on 2022 January 13 from Cape Canaveral.


GRB_name: GRB230427A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33703
SUBJECT: GRB 230427A: Swift-XRT refined Analysis
DATE:    23/04/28 12:54:32 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

A. Tohuvavohu (U. Toronto), D.N. Burrows (PSU), J.P. Osborne (U.
Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), M.
Perri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti
(INAF-OAB), J. D. Gropp (PSU) report on behalf of the Swift-XRT team:

We have analysed 4.5 ks of XRT data for GRB 230427A, from 80 s to 75.0
ks after the  BAT trigger. The data comprise 7 s in Windowed Timing
(WT) mode (taken while Swift was slewing), with the remainder in Photon
Counting (PC) mode. 

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.21 (+0.12, -0.11).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.94 (+0.30, -0.26). The
best-fitting absorption column is  4.0 (+6.6, -3.2) x 10^20 cm^-2,
consistent with the Galactic value of 8.4 x 10^19 cm^-2 (Willingale et
al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux
conversion factor deduced from this spectrum  is 3.3 x 10^-11 (3.6 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      4.0 (+6.6, -3.2) x 10^20 cm^-2
Galactic foreground: 8.4 x 10^19 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.94 (+0.30, -0.26)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01165948.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB230427A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33704
SUBJECT: GRB 230427A: OSIRIS+/GTC observations
DATE:    23/04/28 15:05:51 GMT
FROM:    J. F. Agui Fernandez at IAA-CSIC <feli@iaa.es>

J. F. Agui Fernandez (IAA-CSIC), A. de Ugarte Postigo
(OCA), C. C. Thoene (ASU-CAS), Fabricio Perez, Alvaro
Tejero and A. L. Cabrera Lavers (GTC, IAC) report:

We observed the afterglow of GRB 230427A at ~ 11.3
hours after burst (Page et al. GCN 33687; Takahashi
et al. GCN 33690; Hu et al. GCN  33695; Tohuvavohu
et al. 33703) with OSIRIS+ at the 10.4m GTC telescope,
at the Roque de los Muchachos Observatory (La Palma,
Spain). Observations consisted of 3x1200 s spectroscopy
with grism R1000B, covering the spectral range between
3700 and 7800 AA under good observing conditions.

From the acquisition image we detect a source at the
GRB location and we measure a magnitude of r ~ 24.2
compared to PanSTARRS field stars. We detect a faint
trace at GRB location above ~3950A which set a limit
for the redshift of z < 3.3.


GRB_name: GRB230427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33705
SUBJECT: GRB 230427A: Osservatorio Astronomico Nastro verde upper limit
DATE:    23/04/28 15:20:54 GMT
FROM:    Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy - MPC Code C82 <osservatorionastroverde@gmail.com>

Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy
in a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan), 
Y. Niino (Tokyo University, Institute of Astronomy), 
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Universita' degli Studi Di Salerno)
report: 

We image the field of GRB 230427A detected by SWIFT(trigger 1165948)
with telescope of Nastro Verde Observatory - Sorrento (Naples), Italy. Member of: 
AAVSO - American Association of Variable Star Observers.
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili.
AstroCampania Associazione

The observations started at 19:04 UT of  2023/04/27, after 8,30 hours after the GRB trigger, at the end of twilight
with principal telescope  SC 0.35 f/10 with focal reduced + CCD Sbig ST10 XME
I took 32 image of 120 sec each. All images are unfiltered, calibrated with masterdark and masterflat,stacked with Tycho Tracker software
We have not detected any clearly visible sources, up to 20th magnitude with lightly hazy skies and lunar disturbance
Start T0+                End T0+       Rlim
19:04:53 UT            20:22:52 UT      20

We did not found any optical counterpart in the error box of the XRTcandidate.
Troja et al., GCN 33687



Magnitudes were estimated with the Gaia DR2 cat. and 
are not corrected for galactic dust extinction.



The message may be cited.


GRB_name: GRB230427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33706
SUBJECT: GRB 230427A: Nanshan/HMT optical upper limit
DATE:    23/04/28 15:38:03 GMT
FROM:    Dong Xu at NAOC/CAS <dxu@nao.cas.cn>

S.Q. Jiang, S.Y. Fu, X. Liu, T.H. Lu, D. Xu (NAOC), Z.P. Zhu (NAOC, HUST), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:

We observed the field of GRB 230427A detected by Swift (Troja et al., GCN 33687) using the HMT-0.5m telescope located at Nanshan, Xinjiang, China. Observations started at 14:50:24 UT on 2023-04-27, i.e., 4.3 hr after the Swift/BAT trigger, and 30x60 s unfiltered frames were obtained.

No optical source is detected in our stacked image at the UVOT position (Troja et al., GCN 33687), down to a 3-sigma limiting magnitude m(r) > 21.1 mag (AB) at  4.7 hr post-burst, calibrated with the nearby PanSTAR field in the Sloan r-filter. The magnitude is not corrected for Galactic extinction.


GRB_name: GRB230427A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33707
SUBJECT: GRB 230427A: OHP/T193 spectroscopy observations of WISEA J101316.01+481158.7
DATE:    23/04/28 15:40:52 GMT
FROM:    Benjamin Schneider at MIT <bschn@mit.edu>

C. Adami, M. Garnichey, F. Michel (LAM), B. Schneider (MIT),
S. Basa (LAM), S. D. Vergani (GEPI, Obs. de Paris), D. Turpin, 
D. GÃ¶tz, E. Le Floc'h (CEA Paris-Saclay), report on behalf 
of a larger collaboration:

We re-observed the field of GRB 230427A (Troja et al., GCN 33687) using 
the T193cm telescope at Observatoire de Haute-Provence (France) equipped 
with the MISTRAL spectro-imager. This time, we targeted in spectroscopy 
the galaxy close to the GRB line of sight: WISEA J101316.01+481158.7, at 
r'SDSS(PSF) = 19.6 (AB). Two exposures of 900s were obtained in the blue 
configuration (4200A-8000A) from 2023 28 April 00:25:02 UT to 2023 28 April 
00:55:59 UT. The wavelength calibration was performed using the MISTRAL 
calibration lamp, exposed just after the science observation. Data were 
reduced using the ASPIRED package (https://github.com/cylammarco/ASPIRED) 
configured for MISTRAL data.

In the combined frame, we clearly detect the [NII]@6548A, Halpha, [NII]@6583A, 
and [SII]@6718A. Halpha is the dominant line of the spectrum. Based on these 
lines, we inferred a redshift of z = 0.1524 +/- 0.0005, in good agreement 
with the SDSS photometric redshift of z = 0.13 +/- 0.03.

The GRB is at an offset of ~18 arcsec from the WISEA J101316.01+481158.7 
center. At the redshift of this galaxy, the burst would have a projected 
offset of ~48 kpc and a probability of chance coincidence of ~0.16, 
which is not commonly observed for the long GRB population. For this reason, 
this object is probably not the host galaxy of GRB 230427A.

We acknowledge the excellent support from Observatoire de Haute-Provence, 
in particular Jean Balcaen.


GRB_name: GRB230427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33708
SUBJECT: GRB 230427A: Gaoyazi/GOT optical upper limit
DATE:    23/04/28 15:42:19 GMT
FROM:    Dong Xu at NAOC/CAS <dxu@nao.cas.cn>

S.Y. Fu,  S.Q. Jiang, X. Liu, T.H. Lu, D Xu (NAOC), Z.P. Zhu (NAOC, HUST), S.W. Luo, M.M. Yang, Z. K. Feng (GYZO, NAOC) report:

We observed the field of GRB 230427A detected by Swift (Troja et al., GCN 33687) with the GOT-0.5m telescope located at Gaoyazi, Xinjiang, China. Observations started at 16:34:35 UT on 2023-04-27, i.e., 6.05 hr after the Swift/BAT trigger, 5 x 90 s and 10 x 120 s images were obtained in the Sloan r filter.

No optical source is detected in our stacked image at the UVOT position (Troja et al,. GCN 33687), down to a 3-sigma limiting magnitude r > 20.4 (AB) at 6.32 hr post-burst, calibrated with nearby PanSTARRS stars. The magnitude is not corrected for Galactic extinction.


GRB_name: GRB230427A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33710
SUBJECT: GRB 230427A: Swift/UVOT Detection
DATE:    23/04/28 18:03:41 GMT
FROM:    N. Klingler at NASA-GSFC/UMBC/CRESST II <noelklingler@gmail.com>

N. J. Klingler (GSFC/UMBC/CRESTII) and E. Troja (UToV) report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 230427A 98 s after the BAT trigger (Troja et al., GCN Circ. 33687).  A source consistent with the XRT position (Evans et al. 2023, GCN Circ. 33688) is detected in the initial UVOT exposures.

Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: 

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white               98          248          147         20.19 +/- 0.15
v                  586         4999          255        >19.3
b                  512         1158           58        >19.6
u                  256          854          265        >20.5
w1                 810         5404          231        >20.0
m2                5004         5204          197        >19.6

The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.007 in the direction of the burst (Schlegel et al. 1998).


GRB_name: GRB230427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33711
SUBJECT: GRB 230427A: TSHAO, SAO RAS, AbAO optical upper limit
DATE:    23/04/28 21:28:46 GMT
FROM:    Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>

I. Reva (FAP), A. S. Moskvitin (SAO RAS), O. A. Maslennikova (SAO RAS), R. Ya. Inasaridze (AbAO), A. Volnova (IKI), A. Pozanenko (IKI), N. Pankov (HSE), S. Belkin (IKI) report on behalf of GRB IKI FuN:

We observed the field of Swift GRB 230427A (Troja et al., GCN 33687) in R-filter on 2023-04-27 starting (UT) 15:09:59 with with Zeiss-1000 telescope of TSHAO observatory, (UT) 17:21:56 with Zeiss-1000 telescope of SAO RAS, (UT) 21:56:16 with AS-32 telescope  of Abastumani observatory. We do not detect the optical counterpart of GRB 230427A (Troja et al., GCN 33687; Hu et al., GCN 33695; Agui Fernandez et al., GCN 33704; Klingler et al., GCN 33710). Preliminary photometry of stacked images is following

Date       UT start  t-T0     Exp.  Filter OT   Err.  UL(3sigma) Obs.
                    (mid, days)  (s)

2023-04-27 15:09:59 0.22388  37*120 R      n/d  n/d   21.8     TSAHO
2023-04-27 17:21:56 0.30117   4*300 R      n/d  n/d   21.4     SAO RAS
2023-04-27 21:56:16 0.51140 104*60  R      n/d  n/d   21.0     AbAO

The photometry is based on nearby USNO-B1.0 stars.
USNO-B1.0    R2
1381-0248742 15.71
1381-0240666 16.93
1381-0240629 16.83


GRB_name: GRB230427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33712
SUBJECT: GRB 230427A: NOT optical upper limit
DATE:    23/04/29 15:45:11 GMT
FROM:    Dong Xu at NAOC/CAS <dxu@nao.cas.cn>

Z.P. Zhu (NAOC, HUST), D. B. Malesani (Radboud Univ. and DAWN/NBI), X. Liu, D. Xu (NAOC), report on behalf of a larger collaboration:

We observed the field of GRB 230427A detected by Swift (Troja et al., GCN 33687) using the 2.56-m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Observations started at 23:06:58 UT on 2023-04-27, i.e., ~12.6 hr after the Swift/BAT trigger, and 3x300 s Sloan r-filter images and 5x200 s Sloan z-filter images were obtained, respectively.

No new source is detected in our stacked images at the Swift/UVOT position (Troja et al., GCN 33687), and preliminary photometric results are as follows:

T_mid-T0 (hr)    Filter   Upper_Limit (3-sigma)
    12.7                r          >23.5
    13.0                z          >22.5

calibrated with the nearby Pan-STARRS field and not corrected for Galactic extinction.


GRB_name: GRB230430A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33713
SUBJECT: GRB 230430A: Fermi GBM Final Real-time Localization
DATE:    23/04/30 07:57:58 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely SHORT GRB

At 07:47:18 UT on 30 Apr 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230430A (trigger 704533643.80535 / 230430325).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 184.2, Dec = 40.8 (J2000 degrees, equivalent to J2000 12h 16m, 40d 47'), with a statistical uncertainty of 2.5 degrees.

The angle from the Fermi LAT boresight is 22.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230430325/quicklook/glg_skymap_all_bn230430325.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230430325/quicklook/glg_healpix_all_bn230430325.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230430325/quicklook/glg_lc_medres34_bn230430325.gif


GRB_name: GRB230430A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33714
SUBJECT: GRB 230430A: AstroSat CZTI detection
DATE:    23/05/01 07:00:58 GMT
FROM:    Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>

P K. Navaneeth (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a short GRB 230430A which was also detected by Fermi (Fermi GBM Team, GCN Circ. 33713).

The source was clearly detected in the 20-200 keV energy range. The light curve peaks at 2023-04-30 07:47:18.95 UTC. The measured peak count rate associated with the burst is 4406 (+1160, -973) counts/s above the background in the combined data of all quadrants, with a total of 405 (+71, -61) counts. The local mean background count rate was 423 (+13, -39) counts/s. Using cumulative rates, we measure a T90 of 0.28 (+0.04, -0.02) s.

The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range.

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb


GRB_name: GRB230430A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33715
SUBJECT: GRB 230430A: Fermi GBM observation
DATE:    23/05/02 07:00:05 GMT
FROM:    Joe Mangan at IJCLab <joseph.mangan@ijclab.in2p3.fr>

J.Mangan (CNRS/IJCLab) and C. Meegan (UAH) report on behalf of the Fermi-GBM Team:

"At 07:47:18.81 UT on 30 April 2023, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 230430A (trigger 704533643 / 230430325), which was also detected by AstroSat CZTI (P K. Navaneeth et al. 2023, GCN 33714). The Fermi GBM Final Real-time Localization is reported in GCN 33713.

The angle from the Fermi LAT boresight at the GBM trigger time is 22 degrees.

The GBM light curve consists of a single emission
with a duration (T90) of about 0.32 s (50-300 keV).
The time-averaged spectrum from T0-0.19 s to T0+0.45 s is best fit by
a power law function with an exponential
high-energy cutoff.  The power law index is -0.6 +/- 0.1 and
the cutoff energy, parameterized as Epeak, is 528.4 +/- 58.1 keV. A Band function fits the spectrum equally well with Epeak= 363.8 +/- 57.2 keV, alpha = -0.4 +/- 0.1 and beta = -2.2 +/- 0.3.

The event fluence (10-1000 keV) in this time interval is
(1.7 +/- 0.1)E-6 erg/cm^2. The 64-msec peak photon flux measured
starting from T0+-0.13 s in the 10-1000 keV band
is 25.9 +/- 1.5 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"


GRB_name: GRB230430B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33716
SUBJECT: GRB 230430B: Fermi GBM Final Localization
DATE:    23/05/02 07:06:30 GMT
FROM:    Joe Mangan at IJCLab <joseph.mangan@ijclab.in2p3.fr>

The Fermi GBM team reports the detection of a likely LONG GRB

At 08:50:32 UT on 30 Apr 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230430B (trigger 704537437 / 230430368).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 113.9 Dec = -31.2 (J2000 degrees, equivalent to J2000 7h 36m, -31d 12'), with a statistical uncertainty of 3.02 degrees.

The angle from the Fermi LAT boresight is 27 degrees.

The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230430368/quicklook/glg_skymap_all_bn230430368.png

The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230430368/quicklook/glg_healpix_all_bn230430368.fit

The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230430368/quicklook/glg_lc_medres34_bn230430368.gif


GRB_name: GRB230420A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33717
SUBJECT: GRB 230420A: AROMA-N Optical Upper Limit
DATE:    23/05/02 09:00:50 GMT
FROM:    Takanori Sakamoto at AGU <tsakamoto@phys.aoyama.ac.jp>

Y. Koyanagi, T. Sakamoto (AGU)

We observed the field of GRB 230420A detected by Swift
(Klingler et al., GCN Circ. 33658) with the 14-inch AGU Robotic
Optical Monitor for Astrophysical object - Narrow (AROMA-N)
located at the Sagamihara campus of Aoyama Gakuin University.

13 images of 60 sec exposures were taken in the R filter
starting from April 20 11:41:42 (UT) about 1.37 hours
after the trigger and stopped on April 20 11:59:16 (UT).
We do not detect the optical afterglow both in the individual
images and the stacked image.  The estimated five sigma
upper limit of the combined image (total exposure of 780 sec)
is ~17.1 mag using the USNO-B1 catalog.


GRB_name: GRB230430A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33718
SUBJECT: IPN triangulation of GRB 230430A (short)
DATE:    23/05/02 15:49:34 GMT
FROM:    Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>

A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin
on behalf of the HEND/Mars Odyssey team,

D. Svinkin, D. Frederiks, A. Ridnaia, A. Lysenko,
and T. Cline on behalf of the Konus-Wind team,

A. Goldstein, M. S. Briggs, C. Wilson-Hodge,
and E. Burns on behalf of the Fermi GBM team,

E. Bozzo and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,

and

W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr,
and A.S. Gardner on on behalf of the GRS-Odyssey GRB team,
report:

The short-duration GRB 230430A
(Fermi-GBM detection: the Fermi GBM team, GCN Circ. 33713;
Mangan et al., GCN Circ. 33715;
AstroSat-CZTI detection: Navaneeth et al., GCN Circ. 33714)
was detected by Fermi (GBM trigger 704533643),
Konus-Wind, INTEGRAL (SPI-ACS), AstroSat (CZTI),
and Mars-Odyssey (HEND), at about 28039 s UT (07:47:19).

We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
---------------------------------------------
  RA(2000), deg                 Dec(2000), deg
 ---------------------------------------------
 Center:
  191.335 (12h 45m 20s) +33.912 (+33d 54' 42")
 Corners:
  191.333 (12h 45m 20s) +34.000 (+34d 00' 02")
  191.427 (12h 45m 42s) +34.079 (+34d 04' 45")
  191.338 (12h 45m 21s) +33.823 (+33d 49' 22")
  191.244 (12h 44m 58s) +33.743 (+33d 44' 36")
 ---------------------------------------------
The error box area is 51 sq. arcmin, and its maximum
dimension is 22 arcmin (the minimum one is 3.2 arcmin).
The Sun distance was 125 deg.

This box may be improved.

The IPN localization is consistent with, but reduces the area of,
the Fermi-GBM final localization (GCN 33713).

A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB230430_T28040/IPN

The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.


GRB_name: GRB230430A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33720
SUBJECT: Konus-Wind detection of GRB 230430A
DATE:    23/05/03 14:19:49 GMT
FROM:    Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>

A.Ridnaia, D. Frederiks, A.Lysenko, D. Svinkin,
A. Tsvetkova,  M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:

The short-duration GRB 230430A
(Fermi-GBM detection: Fermi GBM Team, GCN 33713;
Mangan & Meegan, GCN 33715;
AstroSat-CZTI detection: Navaneeth et al., GCN 33714;
IPN triangulation: Kozyrev et al., GCN 33718)
triggered Konus-Wind at T0=28040.858 s UT (07:47:20.858).

The burst light curve shows a multipeaked structure
which starts at ~T0-0.2 s and has a total duration of ~0.3 s.
The emission is seen up to ~8 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB230430_T28040/

As observed by Konus-Wind, the burst
had a fluence of 2.24(-0.38,+0.44)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0-0.008 s,
of 2.04(-0.63,+0.69)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+0.192 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.49(-0.25,+0.31)
and Ep = 704(-180,+254) keV (chi2 = 26/37 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.0
(chi2 = 26/36 dof).

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB230503A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33721
SUBJECT: GRB 230503A: Fermi GBM Final Real-time Localization
DATE:    23/05/03 20:29:45 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 20:19:07 UT on 3 May 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230503A (trigger 704837952.436878 / 230503847).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 66.0, Dec = -48.7 (J2000 degrees, equivalent to J2000 04h 24m, -48d 42'), with a statistical uncertainty of 2.9 degrees.

The angle from the Fermi LAT boresight is 72.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230503847/quicklook/glg_skymap_all_bn230503847.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230503847/quicklook/glg_healpix_all_bn230503847.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230503847/quicklook/glg_lc_medres34_bn230503847.gif


GRB_name: GRB230427A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33722
SUBJECT: GRB 230427A: Swift-BAT refined analysis
DATE:    23/05/03 22:26:28 GMT
FROM:    Sibasish Laha at GSFC <sibasish.laha@nasa.gov>

M. Stamatikos (OSU), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Parsotan (GSFC/UMBC),
T. Sakamoto (AGU), (i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 230427A (trigger #1165948)
(Troja et al., GCN Circ. 33687).  The BAT ground-calculated position is
RA, Dec = 153.339, 48.231 deg which is
   RA(J2000)  =  10h 13m 21.5s
   Dec(J2000) = +48d 13' 52.3"
with an uncertainty of 3.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 86%.

The BAT light curve showed a complex structure with a duration of about 20 sec.
T90 (15-350 keV) is 4.00 +- 1.41 sec (estimated error including systematics).

The time-averaged spectrum from T-0.17 to T+3.83 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.36 +- 0.47.  The fluence in the 15-150 keV band is 9.5 +- 2.9 x 10^-08 erg/cm2.
The 1-sec peak photon flux measured from T-0.17 sec in the 15-150 keV band
is 0.7 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1165948/BA/


GRB_name: GRB230430A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33723
SUBJECT: GRB 230430A: A short GRB from a neutron star merger
DATE:    23/05/04 08:30:05 GMT
FROM:    Remo Ruffini at ICRA <ruffini@icra.it>

R. Ruffini, Y. Aimuratov, L. Becerra, C.L. Bianco, C. Cherubini, S. Filippi, M. Karlica, Liang Li, R. Moradi, F. Rastegar Nia, J.A. Rueda, N. Sahakyan, Y. Wang, S.S. Xue, on behalf of the ICRANet team, report:

GRB 230430A appears to have strong similarities with GRB 090510 originating from merging binary neutron stars (Ruffini et al., 2016). Also in this case no supernova is expected. Attention should be given to the determination of the temporal slope of the late X-ray luminosity which for long GRBs coincide with the common value of the power-law index -1.48+/-0.32 of the afterglow, and for short GRBs appears to have a different power law, to be confirmed (see Fig. 5 in Ruffini et al., 2016). The GeV luminosity for long GRBs has a temporal power-law index -1.19+/-0.04 and for short GRBs it has a temporal power-law index -1.29+/-0.06 (Ruffini et al., 2021). Confirmation of the values of both slopes in GRB 230430A is highly recommended to differentiate short GRBs from long GRBs. We encourage monitoring for the possible appearance of a kilonova signal.

References:
Ruffini, R.; Muccino, M.;  Aimuratov, Y.; et al.; ApJ, 831 (2016) 178.
Ruffini, R.; Moradi, R.; Rueda, J.A; et al.; MNRAS, 504 (2021) 5301.


GRB_name: GRB230420A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33725
SUBJECT: GRB 230420A: Mondy optical afterglow detection, TSHAO, CrAO optical upper limit
DATE:    23/05/05 22:18:02 GMT
FROM:    Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>

N. Pankov (HSE),  A. Pozanenko (IKI), E. Klunko (ISTP), I. Reva (FAPI), V. Rumyantsev (CrAO), S. Belkin (IKI) report on behalf of GRB IKI FuN:

We observed  the field of Swift GRB 230420A (Klingler  et al. GCN 33658) with AZT-33IK telescope of Mondy observatory  in  R-filter on 2023-04-20 starting (UT) 13:31:08, with Zeiss-1000 telescope of of Tien Shan Astronomical Observatory on 2023-04-20 starting (UT) 22:11:07, with Shajn 2.6m telescope of CrAO on  2023-04-22 and 2023-04-23. We detect the afterglow (Hu et al., GCN 33663; Fu et al., GCN 33665; Fausey  et al., GCN 33671; O'Connor et al., GCN 33680) in Mondy observatory and obtained upper limits in TSHAO and CrAO observatories. The afterglow is detected at coordinates of (J2000)  10 44 11.53  +32 06 28.4 which are compatible with NOT estimated coordinates (Fu et al., GCN 33665) and are within Swift XRT enhanced position  (Osborneet al. GCN 33661).

Preliminary photometry  of stacked images is following

Date       UT start t-T0     Exp.  Filter  OT   Err.  UL(3sigma) Observ.
                   (mid, days)  (s)
2023-04-20 13:31:08 0.15424 30*120 R       22.0 0.1   22.8      Mondy
2023-04-20 16:49:25 0.28431 20*120 R       22.7 0.3   22.7      Mondy
2023-04-20 22:11:07 0.36494 31*120 R       n/d  n/d   22.1      TSHAO
2023-04-21 15:23:44 1.25189 27*120 R       n/d  n/d   22.5      Mondy
2023-04-22 18:33:32 2.52854 49*120 R       n/d  n/d   22.6      CrAO
2023-04-23 19:22:36 3.41915 60*120 R       n/d  n/d   23.1      CrAO
2023-04-22+2023-04-23 2.97385 109*120 R    n/d  n/d   23.5      CrAO

The photometry is based on nearby USNO-B1.0 R2 stars.


GRB_name: GRB230506A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33726
SUBJECT: GRB 230506A: Fermi GBM Final Real-time Localization
DATE:    23/05/06 05:18:49 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 05:08:16 UT on 6 May 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230506A (trigger 705042501.650442 / 230506214).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 296.1, Dec = 20.4 (J2000 degrees, equivalent to J2000 19h 44m, 20d 23'), with a statistical uncertainty of 1.6 degrees.

The angle from the Fermi LAT boresight is 35.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230506214/quicklook/glg_skymap_all_bn230506214.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230506214/quicklook/glg_healpix_all_bn230506214.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230506214/quicklook/glg_lc_medres34_bn230506214.gif


GRB_name: GRB230506B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33727
SUBJECT: GRB 230506B: Swift detection of a burst
DATE:    23/05/06 13:28:17 GMT
FROM:    K.L. Page at U Leicester <klp5@leicester.ac.uk>

S. Dichiara (PSU), C. Gronwall (PSU), J. A. Kennea (PSU), A. Y. Lien (U
Tampa), K. L. Page (U Leicester), B. Sbarufatti (INAF-OAB) and M. A.
Williams (PSU) report on behalf of the Neil Gehrels Swift Observatory
Team:

At 12:45:18 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 230506B (trigger=1167266).  Swift slewed immediately to the
burst.
The BAT on-board calculated location is
RA, Dec 326.993, +44.540 which is
   RA(J2000) = 21h 47m 58.32s
   Dec(J2000) = +44d 32' 24.00"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty).  No BAT light-curve is available at this time.

The XRT began observing the field at 12:47:12 UT, 114 seconds after
the BAT trigger. Using promptly downlinked data we find an
uncatalogued X-ray source with an enhanced position: RA, Dec 326.97876,
44.51108 which is equivalent to:
   RA(J2000)  = 21h 47m 54.90s
   Dec(J2000) = +44d 30' 39.9"
with an uncertainty of 6 arcseconds (radius, 90% containment). This
location is 110 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at https://www.swift.ac.uk/sper.

UVOT prompt data are not available at this time.  We are waiting for
the full dataset to search for an UVOT counterpart.

Due to a communications issue, no realtime alerts were received for this
GRB. Therefore, results in this GCN are based on rapidly reported results,
and will be refined in a future GCN Circular.

Burst Advocate for this burst is S. Dichiara (sbd5667 AT psu.edu).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)


GRB_name: GRB230506B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33728
SUBJECT: GRB 230506B: MASTER optical observations
DATE:    23/05/06 15:27:59 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>


V.Lipunov, P.Balanutsa, A.Kuznetsov, N.Tiurina, O.Gress, E.Gorbovskoy, G.Antipov,K.Zhirkov, D.Vlasenko,
Ya.Kechin, A.Chasovnikov,V.Senik, V.Topolev, Yu.Tselik, Siyu Wu, V.Vladimirov, D.Cheryasov (Lomonosov Moscow State University, SAI,Physics Department),
C.Francile, F. Podesta, C.Lopez, R. Podesta (Observatorio Astronomico Felix Aguilar OAFA),
D.A.H.Buckley (SAAO),
R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.Corella,L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory),
N.M.Budnev, O.Ershova (ISU,API),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational State University),
K.Vetrov, V.Shumkov, T.Pogrosheva, E.Minkina, O.Ershova (Lomonosov MSU)

MASTER-Amur robotic telescope  (Global MASTER-Net http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Blagoveshchensk State Pedagogical University) was pointed to the SWIFT GRB230506.53 (trigger No 1167266,21h 47m 54.90s , +44d 30m 39.9s, R=0.1) errorbox  6276 sec after trigger time at 2023-05-06 14:29:54 UT, so as alert didn't come from GCN socket system.

The observations began at zenith distance = 72 deg. The sun  altitude  is -22.3 deg.The galactic latitude b = -7 deg., longitude l = 92 deg.


Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2214809

We obtained following upper limits.

Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

    6367 |         MASTER-Amur |   C |   180 | 16.8 |
    6567 |         MASTER-Amur |   C |   180 | 17.2 |
    6767 |         MASTER-Amur |   C |   180 | 17.3 |
    7037 |         MASTER-Amur |   C |   720 | 18.0 |  Coadd
    6966 |         MASTER-Amur |   C |   180 | 17.3 |
    7166 |         MASTER-Amur |   C |   180 | 17.4 |
    7366 |         MASTER-Amur |   C |   180 | 17.4 |
Filter C is a clear (unfiltred) band.

Observations and analysis will be  continued.
The message may be cited.


GRB_name: GRB230506B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33729
SUBJECT: GRB 230506B: Swift detection of a burst
DATE:    23/05/06 15:35:28 GMT
FROM:    K.L. Page at U Leicester <klp5@leicester.ac.uk>


S. Dichiara (PSU), C. Gronwall (PSU), J. A. Kennea (PSU),
A. Y. Lien (U Tampa), K. L. Page (U Leicester),
B. Sbarufatti (INAF-OAB) and M. A. Williams (PSU) report on behalf of
the Neil Gehrels Swift Observatory Team:

At 12:45:18 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 230506B (trigger=1167266).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 326.993, +44.540 which is 
   RA(J2000) = 21h 47m 58.32s
   Dec(J2000) = +44d 32' 24.00"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  No BAT light-curve is available at this time. 

The XRT began observing the field at 12:47:12 UT, 114 seconds after
the BAT trigger. Using promptly downlinked data we find an
uncatalogued X-ray source with an enhanced position: RA, Dec 326.97876,
44.51108 which is equivalent to:
   RA(J2000)  = 21h 47m 54.90s
   Dec(J2000) = +44d 30' 39.9"
with an uncertainty of 6 arcseconds (radius, 90% containment). This
location is 110 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at https://www.swift.ac.uk/sper. 

UVOT prompt data are not available at this time.  We are waiting for
the full dataset to search for an UVOT counterpart. 

Due to a communications issue, no realtime alerts were received for this GRB. 
Therefore, results in this GCN are based on rapidly reported results, 
and will be refined in a future GCN Circular. 

Burst Advocate for this burst is S. Dichiara (sbd5667 AT psu.edu). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)


GRB_name: GRB230506C
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33731
SUBJECT: GRB 230506C: Swift detection of a burst
DATE:    23/05/06 17:21:56 GMT
FROM:    David Palmer at LANL <palmer@lanl.gov>


A. Tohuvavohu (U Toronto), J. A. Kennea (PSU),
K. L. Page (U Leicester), D. M. Palmer (LANL), M. H. Siegel (PSU) and
M. A. Williams (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 17:09:19 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 230506C (trigger=1167288).  Swift did not immediately slew
due to an observing constraint.  The BAT on-board calculated location is 
RA, Dec 134.373, +45.126 which is 
   RA(J2000) = 08h 57m 30s
   Dec(J2000) = +45d 07' 32"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of about 30 sec.  The peak count rate
was ~1200 counts/sec (15-350 keV), at ~0 sec after the trigger. 

Due to an observing constraint, Swift will not slew until T0+55.3
minutes. There will be no XRT or UVOT data until this time. 

Burst Advocate for this burst is A. Tohuvavohu (aaron.tohu AT gmail.com). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)


GRB_name: GRB230506B
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33733
SUBJECT: GRB 230506B: Swift/UVOT Detection
DATE:    23/05/06 21:37:07 GMT
FROM:    Paul Kuin at MSSL <npkuin@gmail.com>

Paul Kuin (MSSL/UCL) and Simone Dichiara(PSU) report on behalf
of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 230506B
114 s after the BAT trigger (Dichiara et al., GCN Circ. 33727).
A candidate afterglow consistent with the XRT position is
detected in the initial UVOT exposures.

Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white              113          271          147          20.19 +/- 0.24
white              614          807           38         >19.8
u                  334          583          247         >19.9
u                10511        11899          738          20.66 +/- 0.30
b                  589          783           39         >19.1
uvw1               714          734           20         >17.6
uvm2               688          708           20         >17.2
uvw2               639          658           20         >19.6

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.293 in the direction of the burst
(Schlegel et al. 1998).

[GCN OPS NOTE: Corrected title from 230606B to 230506B at author's request.]


GRB_name: GRB230506C
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33734
SUBJECT: GRB  230506C: TSHAO possible afterglow candidate
DATE:    23/05/06 23:13:08 GMT
FROM:    Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>

N. Pankov (HSE), I. Reva (FAI), A. Pozanenko (IKI),  S. Belkin (IKI)  report on behalf of GRB-IKI-FuN:

We observed the field of  GRB 230506C detected by Swift (Tohuvavohu et al., GCN  33731)  with Zeiss-1000 telescope of Tien Shan Astronomical Observatory stating on May, 06 (UT) 17:24:54 in R-filter.

Within Swift-BAT error circle (Tohuvavohu et al., GCN  33731)  we  detected uncatalogued object in coordinates of (J2000) 08:57:28.13 +45:07:59.48 with uncertainties of 0.3 arcsec in each coordinate.  The object is absent in SDSS images. A distance of the object from the center of BAT error circle is ~30 arces. Preliminary photometry of a stacked images is following

Date       UT start t-T0    Filter  Exp.    OT     Err.  UL(3 sigma)
                    (mid, days)     (s)

2023-05-06 17:24:54 0.02914  R      23*120  20.1  0.1  21.5
 
The photometry is based on nearby USNO-B1.0 stars.
We suggest that the object is a candidate for the afterglow of GRB 230506C.


GRB_name: GRB230506C
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33735
SUBJECT: GRB 230506C: Candidate afterglow observation by D50
DATE:    23/05/06 23:44:46 GMT
FROM:    Martin Jelinek at Astro.Inst-AVCR,Ondrejov <martin.jelinek@asu.cas.cz>

M. Jelinek, J. Strobl, R. Hudec, C. Polasek (ASU CAS Ondrejov) report:

We observed the position of the Swift-detected GRB 220506C (Tohuvavohu et
al.
GCNC 33731) with the D50 telescope of the Astronomical Institute Ondrejov,
near
Prague, Czech Republic. Our observation started at 19:58 UT, i.e. 2.8 h
after
the initial trigger and was performed with an SDSS i' filter.

We confirm the presence of an object not present in the SDSS survey
reported by
Pankov et al. (GCNC 33734) in a combined image with exp. mean time ~4.0 h
after
trigger (exposed 19:58--22:35UT). The AB magnitude of the object in this
frame
is i' = 20.54 +/- 0.11.


GRB_name: GRB230506C
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33736
SUBJECT: GRB 230506C: Swift-XRT analysis
DATE:    23/05/07 00:20:13 GMT
FROM:    Jamie Kennea at Penn State U <jak51@psu.edu>

J. A. Kennea (PSU), A. Tohuvavohu (Toronto), P.A. Evans and 
M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team:

We have analysed 1.6 ks of XRT data for GRB 230506C, from 4.6 ks to
11.0 ks after the BAT trigger. The data are entirely in Photon
Counting (PC) mode. Using 1145 s of PC mode data and 2 UVOT images, we
find an enhanced XRT position (using the XRT-UVOT alignment and
matching UVOT field sources to the USNO-B1 catalogue): RA, Dec =
134.36766, +45.13302 which is equivalent to:

RA (J2000): 08h 57m 28.24s
Dec(J2000): +45d 07' 58.9"

with an uncertainty of 2.4 arcsec (radius, 90% confidence).
This circular is an official product of the Swift-XRT team.

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.0 (+0.5, -0.4).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.2 (+0.4, -0.3). The
best-fitting absorption column is 1.2 (+0.9, -0.8) x 10^21 cm^-2, in
excess of the Galactic value of 2.2 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum is 3.0 x 10^-11 (4.1 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column: 1.2 (+0.9, -0.8) x 10^21 cm^-2
Galactic foreground: 2.2 x 10^20 cm^-2
Excess significance: 2.2 sigma
Photon index: 2.2 (+0.4, -0.3)

If the light curve continues to decay with a power-law decay index of
1.0, the count rate at T+24 hours will be 0.012 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.8 x
10^-13 (5.1 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01167288.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB230506B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33737
SUBJECT: GRB 230506B: Swift-XRT refined Analysis
DATE:    23/05/07 05:44:37 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

D.N. Burrows (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U.
Leicester), P.A. Evans (U. Leicester), V. D'Elia (SSDC & INAF-OAR), B.
Sbarufatti (INAF-OAB), A. D'Ai (INAF-IASFPA), J. D. Gropp (PSU), S.
Dichiara (PSU) report on behalf of the Swift-XRT team:

We have analysed 7.9 ks of XRT data for GRB 230506B, from 68 s to 50.9
ks after the  BAT trigger. The data comprise 124 s in Windowed Timing
(WT) mode (the first 9 s were taken while Swift was slewing) with the
remainder in Photon Counting (PC) mode. Using 335 s of PC mode data and
1 UVOT image, we find an enhanced XRT position (using the XRT-UVOT
alignment and matching UVOT field sources to the USNO-B1 catalogue):
RA, Dec = 326.98168, +44.51111 which is equivalent to:

RA (J2000): 21h 47m 55.60s
Dec(J2000): +44d 30' 40.0"

with an uncertainty of 2.6 arcsec (radius, 90% confidence).

The light curve can be modelled with an initial power-law decay with an
index of alpha=1.83 (+0.16, -0.17), followed by a break at T+146 s to
an alpha of 4.87 (+0.29, -0.24).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.45 (+/-0.13). The
best-fitting absorption column is  5.8 (+1.3, -1.1) x 10^21 cm^-2, in
excess of the Galactic value of 3.8 x 10^21 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 5.6 x 10^-11 (7.1 x 10^-11) erg
cm^-2 count^-1. 

A summary of the WT-mode spectrum is thus:
Total column:      5.8 (+1.3, -1.1) x 10^21 cm^-2
Galactic foreground: 3.8 x 10^21 cm^-2
Excess significance: 3.0 sigma
Photon index:      1.45 (+/-0.13)

If the light curve continues to decay with a power-law decay index of
4.87, the count rate at T+24 hours will be 5.0 x 10^-13 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.8 x
10^-23 (3.6 x 10^-23) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01167266.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB230506C
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33738
SUBJECT: GRB 230506C: NUTTelA-TAO / BSTI Early Optical Limits
DATE:    23/05/07 10:19:24 GMT
FROM:    Toktarkhan Komesh at Nazarbayev University <toktarkhan.komesh@nu.edu.kz>

T. Komesh (NU), B. Grossan (UCB, NU), Zh. Maksut (NU), Zh. Abdullayev (NU), N. Shaimoldin (NU), M. Krugov (FAI), report on behalf of the Energetic Cosmos Laboratory:

The Nazarbayev University Transient Telescope at Assy-Turgen Astrophysical Observatory (NUTTelA-TAO) observed the field of GRB 230506C, 8 s after receipt an automated GCN / BAT position alert, observing in Sloan i' band, with the Burst Simultaneous Three-Channel Imager (BSTI; Grossan, Kumar & Smoot 2019, JHEA, 32, 14).

We started observations at 17:09:56 UT on 2023-05-06, 37 s after the BAT trigger. Observations were made in cloudy conditions. No source consistent with the XRT (J. A. Kennea et al., GCN Circ. 33736) was detected. We report the following results:

start time   t-t0(s)     end time        ULi'   exposure_time (s)
------------    -----       -----------     -----      ------
17:09:56     37      17:10:48          17.4 52.5
17:11:03    104     17:13:33       18.0    150

start time is in UT. t-t0(s) gives the time since trigger, in seconds. UL i', gives the 5 sigma upper limit sensitivity in magnitudes, for images co-added to the given exposure time. The first row in the table corresponds to co-adds of an initial short exposure image sequence of 7.5 s. The second row corresponds to co-adds from a continuing series of 15 s exposures. Calibration was done with the 3 bright Pan-STARRS catalog stars on our images.

----------------------------------
NU = Nazarbayev University, Nur-Sultan, Kazakhstan
UCB = University of California, Berkeley, USA
FAI = Fesenkov Astrophysical Institute, Kazakhstan

This research has been funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan (Grant No. AP14870504). The NUTTelA-TAO Team acknowledges the support of the staff of the Assy-Turgen Astrophysical Observatory, Almaty, Kazakhstan, and the Fesenkov Astrophysical Institute, Almaty, Kazkhstan.


GRB_name: GRB230506C
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33739
SUBJECT: GRB 230506C: Swift/UVOT Upper Limits
DATE:    23/05/07 11:27:27 GMT
FROM:    Paul Kuin at MSSL <npkuin@gmail.com>

Paul Kuin (MSSL/UCL) and A Tohuvavohu (U Toronto) report on behalf
of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 230506C
4.6 ks after the BAT trigger (Tohuvavohu et al., GCN Circ. 33731).
No optical afterglow consistent with the enhanced XRT position is
detected in the initial UVOT exposures.

Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white             4625         4825          197         >18.5
v                 5036         5236          197         >19.2
u                 5614         5814          197         >19.6
uvw1              5446         5646          197         >20.6
uvm2              5241         5441          197         >21.5
uvw2              4831         5031          197         >20.3


GRB_name: GRB230506B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33740
SUBJECT: GRB 230506B: LCOGT Optical Upper Limits
DATE:    23/05/07 15:34:37 GMT
FROM:    Robert Strausbaugh at University of Minnesota <rstrausb@umn.edu>

R. Strausbaugh (University of Minnesota), A. Cucchiara (NASA) report on
behalf of a larger collaboration:

We observed the GRB 230506B (Dichiara et al., GCN 33727) field with the
LCOGT 1-meter Sinistro instrument at the Teide Observatory, Tenerife site,
on May 7, from 04:09 to 04:41 UT (corresponding to 15.43 to 15.93 hours
from the GRB trigger time) with the SDSS r and i filters.

We performed a series of 3x300s exposures in each band.  We do not detect
an uncatalouged source within the Swift-XRT error region in either band.

The following upper limits are calculated using the PanSTARRS catalog as
reference:

r > 22.3
i > 21.8

These magnitudes are not corrected for galactic extinction.


GRB_name: GRB230506C
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33741
SUBJECT: GRB 230506C: spectro-imaging observations of the optical afterglow with T193-OHP
DATE:    23/05/07 18:22:12 GMT
FROM:    Emeric Le Floc'h at CEA-Saclay <emeric.lefloch@cea.fr>

C. Adami, S. Basa (LAM), E. Le Flocâ€™h, D. GÃ¶tz, D.Turpin (CEA Paris-Saclay), B. Schneider (MIT), S. D. Vergani (GEPI, Obs. de Paris), report on behalf of a larger collaboration:

We observed the field of GRB 230506C (Tohuvavohu et al., GCN 22731) using the T193cm telescope at Observatoire de Haute-Provence (France) equipped with the MISTRAL spectro-imager. 5 exposures were obtained in the imaging mode with the r-band filter (4x300s + 1x600s) from 2023 6 May 20:46:12 UT to 2023 6 May 21:16:27 UT (mid time ~3.8h after trigger). In the combined frame, we detect a source consistent with the position of the X-ray counterpart reported by Kennea et al. (GCN 33736) and with the location of the optical afterglow reported by Pankov et al. (GCN 33734) and Jelinek et al. (GCN 33735). The râ€™ AB magnitude of this source is 20.9 +/- 0.06 mag. The photometric calibration was performed using nearby stars from the PanSTARRS catalog and the magnitude is not corrected for Galactic extinction.

In addition, we exposed for 30min (2x15min) with the MISTRAL spectroscopic blue setting, covering from 4200A to 8000A, at R~750. We detect a faint continuum at the GRB position, clearly visible at wavelength redder than ~5100A, but the absence of continuum at Lambda bluer than 5100A may be due to the lack of efficiency of the instrument. The S/N is also too low to provide any significant emission or absorption line detection.

We acknowledge the excellent support from Observatoire de Haute-Provence, in particular Jean-Pierre Troncin. 


GRB_name: GRB230506B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33742
SUBJECT: GRB 230506B: Swift-BAT refined analysis
DATE:    23/05/07 18:41:10 GMT
FROM:    Amy Lien at GSFC <amy.y.lien@nasa.gov>

S. D. Barthelmy (GSFC), S. Dichiara (PSU),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Parsotan (GSFC/UMBC),
T. Sakamoto (AGU), M. Stamatikos (OSU)
(i.e. the Swift-BAT team):

Using the data set from T-240 to T+962 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 230506B (trigger #1167266)
(Dichiara et al., GCN Circ. 33727).  The BAT ground-calculated position is
RA, Dec = 326.986, 44.514 deg which is
   RA(J2000)  =  21h 47m 56.6s
   Dec(J2000) = +44d 30' 50.9"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 73%.

The mask-weighted light curve shows a multi-peaked structure that
starts at ~T0 and ends at ~T+80 s. The main peak occurs at ~T+11 s.
T90 (15-350 keV) is 61.54 +- 10.89 sec (estimated error
including systematics).

The time-averaged spectrum from T+0.02 to T+76.30 sec is best fit
by a simple power-law model.  The power law index of the time-averaged
spectrum is 1.41 +- 0.11.  The fluence in the 15-150 keV band
is 2.9 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured
from T+10.60 sec in the 15-150 keV band is 4.6 +- 0.4 ph/cm2/sec.
All the quoted errors are at the 90% confidence level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1167266/BA/


GRB_name: GRB230506C
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33743
SUBJECT: GRB 230506C: Swift-BAT refined analysis
DATE:    23/05/07 18:42:20 GMT
FROM:    Amy Lien at GSFC <amy.y.lien@nasa.gov>

H. A. Krimm (NSF), S. D. Barthelmy (GSFC),
S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU),
M. Stamatikos (OSU), A. Tohuvavohu (U Toronto)
(i.e. the Swift-BAT team):

Using the data set from T-240 to T+962 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 230506C (trigger #1167288)
(Tohuvavohu et al., GCN Circ. 33731).  The BAT ground-calculated position is
RA, Dec = 134.371, 45.131 deg which is
   RA(J2000)  =  08h 57m 29.1s
   Dec(J2000) = +45d 07' 50.7"
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 46%.

The mask-weighted light curve shows a multi-peaked structure that starts
at ~T-9 s and ends at ~T+28 s. The main peak occurs at ~T+1 s.
T90 (15-350 keV) is 31.00 +- 6.32 sec (estimated error
including systematics).

The time-averaged spectrum from T-8.59 to T+28.41 sec is best fit by
a simple power-law model.  The power law index of the time-averaged
spectrum is 1.89 +- 0.17.  The fluence in the 15-150 keV band
is 1.7 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured
from T+0.41 sec in the 15-150 keV band is 2.4 +- 0.5 ph/cm2/sec.
All the quoted errors are at the 90% confidence level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1167288/BA/


GRB_name: GRB230506C
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33744
SUBJECT: GRB 230506C: Swift-XRT refined Analysis
DATE:    23/05/07 22:44:46 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), J.P. Osborne
(U. Leicester), B. Sbarufatti (INAF-OAB), A. D'Ai (INAF-IASFPA), A.
Melandri (INAF-OAR), J. D. Gropp (PSU), S. Dichiara (PSU), J.A. Kennea
(PSU) report on behalf of the Swift-XRT team:

We have analysed 6.2 ks of XRT data for GRB 230506C, from 4.6 ks to
97.1 ks after the  BAT trigger. The data are entirely in Photon
Counting (PC) mode. Using 1929 s of PC mode data and 5 UVOT images, we
find an enhanced XRT position (using the XRT-UVOT alignment and
matching UVOT field sources to the USNO-B1 catalogue): RA, Dec =
134.36764, +45.13295 which is equivalent to:

RA (J2000): 08h 57m 28.23s
Dec(J2000): +45d 07' 58.6"

with an uncertainty of 2.1 arcsec (radius, 90% confidence).

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.81 (+0.11, -0.10).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.09 (+0.25, -0.23). The
best-fitting absorption column is  9.1 (+6.2, -5.3) x 10^20 cm^-2, in
excess of the Galactic value of 2.2 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.1 x 10^-11 (3.9 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      9.1 (+6.2, -5.3) x 10^20 cm^-2
Galactic foreground: 2.2 x 10^20 cm^-2
Excess significance: 2.2 sigma
Photon index:      2.09 (+0.25, -0.23)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01167288.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB230307A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33747
SUBJECT: GRB 230307A: JWST second-epoch observations
DATE:    23/05/08 21:30:32 GMT
FROM:    Andrew Levan at Radboud University <a.levan@astro.ru.nl>

A.J. Levan (Radboud), N. R. Tanvir (U. Leicester), E. Burns (LSU), G.P. Lamb (LJMU), J. P. U. Fynbo (DAWN/NBI), A.S. Fruchter (STScI), K. Bhirombhakdi (STScI), P Oâ€™Brien (U. Leicester), P. Jakobsson (U. Iceland), D. B. Malesani (Radboud and DAWN/NBI), B. P. Gompertz (U. Birmingham), A. Martin-Carrillo (UCD), D. Watson (DAWN/NBI), S. Smartt (Oxford) , J. Hjorth (DARK/NBI) report for a larger collaboration: 

We obtained a second epoch of JWST observations of the exceptionally bright GRB 230307A (Fermi GBM team, GCN 33405; Xiong et al., GCN 33406; Xiao & Krucker, GCN 33410; Cosentini et al., GCN 33412; Navaneeth et al., GCN 33415) on 8 May 2023 (about 62 days post-burst). Imaging was obtained with NIRCam in the F115W, F150W, F277W and F444W filters and spectroscopy with the NIRSpec prism.

The source at the location of the optical/IR afterglow (Levan et al., GCNs 33439, 33569) is still detected but has faded significantly, particularly in the redder bands. In the F444W filter, it faded by 2.7 mag. 

This result confirms that the very red continuum noted in the first epoch by Levan et al. (GCN 33569) is due to a variable source and does not contain a significant contribution from any underlying host. However, we do note the presence of a faint galaxy, approximately 0.3â€ from the burst position, which is plausibly the source of the emission lines seen in previous NIRSpec spectroscopy (Levan et al., GCN 33580). Although further analysis is required, the rapid IR fading is consistent with the expectations of kilonova emission. If that interpretation is correct, the higher redshift source has to be an unrelated background galaxy, aligned by chance with the GRB. Alternatively, if associated with the galaxy at z = 3.87, the counterpart would have exhibited unprecedented temporal and chromatic behaviour. 


GRB_name: GRB230506C
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33748
SUBJECT: GRB 230506C: SAO RAS optical observations
DATE:    23/05/09 16:04:41 GMT
FROM:    Moskvitin Alexander at SAO RAS <mosk@sao.ru>

A. Moskvitin, O. Maslennikova (SAO), N. Pankov (HSE, IKI)
and A. Pozanenko (IKI), report on behalf of GRB follow-up team.

We observed the field of GRB 230506C (Tohuvavohu et al., GCN 22731)
with the SAO RAS 1-m telescope Zeiss-1000 + CCD photometer.
The observations started since 1.3528 hours after the trigger
under mediocre weather conditions. We obtained 3 x 300 sec. exposures
in Rc band (May 6, 18:30:29 -- 18:48:26 UT, T_mid - T_0 = 1.5024 h).

The OT (Kuin & Dichiara, GCN 33733; Pankov et al., GCN 33734;
Jelinek et al., GCN 33735; Adami et al., GCN 33741) is marginally
detected in the stacked image with the brightness of R = 20.5 +/- 0.3.
Preliminary photometry is based on R2 magnitudes of nearby USNO-B1
stars. The OT magnitude is not corrected for the Galactic extinction.


GRB_name: GRB230506C
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33749
SUBJECT: GRB 230506C: T193-OHP MISTRAL tentative redshift
DATE:    23/05/10 06:47:00 GMT
FROM:    Damien Turpin at CEA-Saclay <dturpin-astro@hotmail.com>

C. Adami (LAM), J. Palmerio, S. D. Vergani (GEPI, Obs. de Paris), B. Schneider (MIT), E. Le Flocâ€™h, D. GÃ¶tz, D.Turpin (CEA Paris-Saclay), S. Basa (LAM) report on behalf of a larger collaboration:

We performed a refined analysis of our spectrum (Adami et al. GCN33741) of GRB 230506C (Tohuvavohu et al., GCN 33731, Jelinek et al. GCN 33735, Moskvitin et al. GCN 33748) taken at OHP/T193 with the MISTRAL spectroscopic blue setting, covering from 4200A to 8000A, at R~750 (midtime = T0+4.4h) .

Despite the very low quality of the spectrum, due to the faintness of the object, we can identify a break that we tentatively interpret as a Lyman-alpha break, and for which we find a corresponding Lyman-limit flux drop, indicating 3.7<z<~4.0.

We acknowledge the excellent support from Observatoire de Haute-Provence, in particular Jean Pierre Troncin, the SOPHIE observer Daniel Sebastian and the LAM AMAZED team.


GRB_name: GRB230506B
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33750
SUBJECT: GRB 230506B: Swift/UVOT further analysis
DATE:    23/05/10 07:58:44 GMT
FROM:    Paul Kuin at MSSL <npkuin@gmail.com>

Paul Kuin (MSSL/UCL) reports on behalf of the Swift/UVOT team:

The XRT position of GRB230506B falls on a Gaia DR3 source of magnitude
BP = 19.89, Gmag = 19.34. We see from further analysis of the UVOT data
that within errors the detections are consistent with the Gaia source.
The UVOT data are therefore not the optical afterglow of the GRB.


GRB_name: GRB230510A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33751
SUBJECT: GRB 230510A: Fermi GBM Final Real-time Localization
DATE:    23/05/10 12:14:55 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 12:04:06 UT on 10 May 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230510A (trigger 705413051.934178 / 230510503).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 322.3, Dec = 31.0 (J2000 degrees, equivalent to J2000 21h 29m, 31d 00'), with a statistical uncertainty of 2.6 degrees.

The angle from the Fermi LAT boresight is 14.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230510503/quicklook/glg_skymap_all_bn230510503.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230510503/quicklook/glg_healpix_all_bn230510503.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230510503/quicklook/glg_lc_medres34_bn230510503.gif


GRB_name: GRB230510A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33752
SUBJECT: GRB 230510A: Swift detection of a burst
DATE:    23/05/10 12:44:51 GMT
FROM:    K.L. Page at U Leicester <klp5@leicester.ac.uk>


R. A. J. Eyles-Ferris (U Leicester), P. A. Evans (U Leicester),
J.D. Gropp (PSU), J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC),
K. L. Page (U Leicester), P. Romano (INAF-OAB), T. Sakamoto (AGU),
B. Sbarufatti (INAF-OAB) and M. A. Williams (PSU) report on behalf of
the Neil Gehrels Swift Observatory Team:

At 12:06:28 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 230510A (trigger=1167973).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 318.156, +34.443 which is 
   RA(J2000) = 21h 12m 37s
   Dec(J2000) = +34d 26' 33"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex 
structure with a duration of about 60 sec.  The peak count rate
was ~5100 counts/sec (15-350 keV), at ~13 sec after the trigger. 

The XRT began observing the field at 12:07:31.9 UT, 63.4 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 318.1314, 34.4424 which is equivalent to:
   RA(J2000)  = 21h 12m 31.54s
   Dec(J2000) = +34d 26' 32.6"
with an uncertainty of 6.5 arcseconds (radius, 90% containment). This
location is 73 arcseconds from the BAT onboard position, within the BAT
error circle. No event data are yet available to determine the column
density using X-ray spectroscopy. 

The initial flux in the 0.1 s image was 1.19e-08 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 72 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.144. 

This trigger was initially marked as matching a source in the BAT
ground catalogue: IGR J21117+3427, a known gamma-ray source. However,
the XRT localisation is more than 9 arcmin from the known position of
IGR J21117+3427, outside its error region of 3.5 arcmin (ATel 873). 
This, together with the BAT transient monitor light-curve showing
little sign of variation suggests that this is in fact a new GRB. 

Burst Advocate for this burst is R. A. J. Eyles-Ferris (raje1 AT leicester.ac.uk). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)


GRB_name: GRB230506C
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33755
SUBJECT: GRB 230506C: Fermi GBM detection
DATE:    23/05/10 17:37:35 GMT
FROM:    Suraj Poolakkil at UAH <sp0076@uah.edu>

S. Poolakkil (UAH) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 17:09:16.97 UT on 6 May 2023, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 230506C (trigger 705085761 / 230506715)
which was also detected by the Swift/BAT (Tohuvavohu et al. 2023, GCN 33731).

The angle from the Fermi LAT boresight at the GBM trigger time is 15 degrees.

The GBM light curve consists of a single peak followed
by some extended emission with a duration (T90) of about 23 s (50-300 keV).
The time-averaged spectrum from T0-6.1 s to T0+11.3 s
is best fit by a power law function with an exponential
high-energy cutoff. The power law index is -1.19 +/- 0.11  and
the cutoff energy, parameterized as Epeak, is 163 +/- 30 keV.

The event fluence (10-1000 keV) in this time interval is
(3.1 +/- 0.3)E-06  erg/cm^2. The 1-sec peak photon flux measured
starting from T0+3.0 s in the 10-1000 keV band
is 3.3 +/- 0.2 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"


GRB_name: GRB230510A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33756
SUBJECT: GRB 230510A: Enhanced Swift-XRT position
DATE:    23/05/10 18:57:48 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 1466 s of XRT Photon Counting mode data and 4 UVOT
images for GRB 230510A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 318.13672, +34.44306 which is equivalent
to:

RA (J2000): 21h 12m 32.81s
Dec (J2000): +34d 26' 35.0"

with an uncertainty of 2.2 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB230510A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33757
SUBJECT: GRB 230510A: Swift-XRT refined Analysis
DATE:    23/05/10 21:19:36 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), A. D'Ai
(INAF-IASFPA), A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB), S.
Dichiara (PSU), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), K.L.
Page (U. Leicester) report on behalf of the Swift-XRT team:

We have analysed 6.3 ks of XRT data for GRB 230510A, from 52 s to 23.0
ks after the  BAT trigger. The data comprise 250 s in Windowed Timing
(WT) mode (the first 10 s were taken while Swift was slewing) with the
remainder in Photon Counting (PC) mode. 

The late-time light curve (from T0+4.2 ks) can be modelled with a
power-law decay with a decay index of alpha=0.92 (+/-0.09).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.19 (+/-0.05). The
best-fitting absorption column is  2.53 (+0.17, -0.16) x 10^21 cm^-2,
in excess of the Galactic value of 1.9 x 10^21 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.99 (+0.13, -0.08)
and a best-fitting absorption column of 1.938 (+0.454, -0.025) x 10^21
cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.5 x 10^-11 (4.8 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.938 (+0.454, -0.025) x 10^21 cm^-2
Galactic foreground: 1.9 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.99 (+0.13, -0.08)

If the light curve continues to decay with a power-law decay index of
0.92, the count rate at T+24 hours will be 0.035 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.2 x
10^-12 (1.7 x 10^-12) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01167973.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB230506B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33758
SUBJECT: GRB 230506B: Fermi GBM detection
DATE:    23/05/10 21:19:49 GMT
FROM:    Oliver J Roberts at USRA/NASA <oliver.roberts@nasa.gov>

O.J. Roberts (USRA/NASA-MSFC), S. Bala (USRA), C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 12:45:18.77 UT on 06 May 2023, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 230506B (trigger 705069923 / 230506531), which was
also detected by the Swift/BAT (S. Dichiara et al. 2023, GCN 33729 and 
S.D. Barthelmy et al. 2023, GCN 33742). The GBM on-ground location is 
consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 47 degrees.

The GBM light curve consists of multiple short bursts
with a duration (T90) of about 38 s (50-300 keV).
The time-averaged spectrum from T0-0.8 s to T0+39.2 s is best fit by
a power law function with an exponential
high-energy cutoff. The power law index is -1.28 +/- 0.04 and
the cutoff energy, parameterized as Epeak, is 1767 +/- 576 keV

The event fluence (10-1000 keV) in this time interval is
(1.13 +/- 0.04)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+10.4 s in the 10-1000 keV band
is 8.1 +/- 0.3 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"


GRB_name: GRB230510B
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33759
SUBJECT: GRB 230510B: Fermi GBM Final Real-time Localization
DATE:    23/05/10 21:32:13 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 21:21:34 UT on 10 May 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230510B (trigger 705446499.012602 / 230510890).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 4.5, Dec = 30.0 (J2000 degrees, equivalent to J2000 00h 18m, 30d 00'), with a statistical uncertainty of 1.0 degrees.

The angle from the Fermi LAT boresight is 66.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230510890/quicklook/glg_skymap_all_bn230510890.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230510890/quicklook/glg_healpix_all_bn230510890.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230510890/quicklook/glg_lc_medres34_bn230510890.gif


GRB_name: GRB230510B
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33760
SUBJECT: GRB 230510B: MAXI/GSC detection
DATE:    23/05/10 23:29:07 GMT
FROM:    Satoshi Sugita at Aoyama Gakuin U. <sugita@phys.aoyama.ac.jp>

M. Nakajima (Nihon U.), Y. Kawakubo (LSU), S. Sugita, M. Serino (AGU),
H. Negoro, K. Kobayashi, M. Tanaka, Y. Soejima, Y. Kudo (Nihon U.),
T. Mihara, T. Kawamuro, S. Yamada, T. Tamagawa, N. Kawai, M. Matsuoka (RIKEN),
T. Sakamoto, H. Hiramatsu, H. Nishikawa, A. Yoshida (AGU),
Y. Tsuboi, S. Urabe, S. Nawa, N. Nemoto (Chuo U.),
M. Shidatsu (Ehime U.),
I. Takahashi, M. Niwano, S. Sato, N. Higuchi, Y. Yatsu (Tokyo Tech),
S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, S. Ogawa, T. Kurihara (JAXA),
Y. Ueda, K. Setoguchi, T. Yoshitake, Y. Nakatani (Kyoto U.),
M. Yamauchi, Y. Hagiwara, Y. Umeki, Y. Otsuki (Miyazaki U.),
K. Yamaoka (Nagoya U.),
M. Sugizaki (NAOC),
W. Iwakiri (Chiba U.)
report on behalf of the MAXI team:

The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray
transient source at  21:22:03 UT 10 May 2023.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (0.692 deg, 27.541 deg) = (00 02 46, +27 32 27) (J2000)
with a statistical 90% C.L. elliptical error region
with long and short radii of 0.15 deg and 0.14 deg, respectively.
The roll angle of long axis from the north direction is 139.0 deg
counterclockwise.
Without assumptions on the source constancy, we obtain a rectangular error
box for the transient source with the following corners:
(R.A., Dec) = (0.127, 28.437) deg = (00 00 30, +28 26 13) (J2000)
(R.A., Dec) = (359.878, 28.290) deg = (23 59 30, +28 17 23) (J2000)
(R.A., Dec) = (0.966, 26.843) deg = (00 03 51, +26 50 34) (J2000)
(R.A., Dec) = (1.213, 26.988) deg = (00 04 51, +26 59 16) (J2000)
There is an additional systematic uncertainty of 0.1 deg (90%
containment radius).
The trigger time and position was consistent with that of GRB 230510B
(Fermi GBM, GCN 33759)
The X-ray flux averaged over the scan was 635 +- 75 mCrab
(4.0-10.0keV, 1 sigma error).
There was no significant excess flux in the previous transit at 19:49 UT
and in the next transit at 22:54 UT with an upper limit of 20 mCrab for each.


GRB_name: GRB230510A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33761
SUBJECT: GRB 230510A: Nanshan/NEXT optical afterglow detection
DATE:    23/05/11 03:06:34 GMT
FROM:    Dong Xu at NAOC/CAS <dxu@nao.cas.cn>

S.Q. Jiang, T.H. Lu, S.Y. Fu, X. Liu, D. Xu (NAOC), Z.P. Zhu (NAOC, HUST), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:

We observed the field of GRB 230510A detected by Swift (Eyles-Ferris et al., GCN 33752) and Fermi (Fermi GBM team, GCN 33751) using the NEXT-0.6m telescope located at Nanshan, Xinjiang, China. Observations started at 18:47:49.1 UT on 2023-05-10, i.e., 6.69 hr after the Swift/BAT trigger, and 12x200 s exposures have been obtained in the Sloan r-filter.

We detected an uncatalogued optical transient (OT) within the enhanced Swift/XRT error circle (Evans et al., GCN 33756) at coordinates

R.A. (J2000) = 21:12:32.87
Dec.(J2000) = +34:26:35:59

with an uncertainty of ~ 0.5 arcsec, and it has m(r) = 20.5 +/- 0.1 mag in the co-added image at 7.27 hr post-burst, calibrated with the nearby PanSTAR field. PanSTAR covers this position and is much deeper, but the OT is not present. We thus conclude that the OT is the optical afterglow of the burst.


GRB_name: GRB230510A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33762
SUBJECT: GRB 230510A: CALET Gamma-Ray Burst Monitor detection
DATE:    23/05/11 06:18:01 GMT
FROM:    Yuta Kawakubo at Louisiana State University <kawakubo1@lsu.edu>

S. Ricciarini (U of Florence), A. Yoshida, T. Sakamoto, S. Sugita (AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN),
Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (Waseda U),
Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC),
M. L. Cherry (LSU), P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

The long GRB 230510A (Fermi GBM Final Real-time Localization: Fermi GBM team,
GCN Circ. 33751; Swift detection: Eyles-Ferris et al., GCN Circ. 33752) 
triggered the CALET Gamma-ray Burst Monitor (CGBM) at 12:06:22.60 UTC on 10 May 2023
(http://cgbm.calet.jp/cgbm_trigger/flight/1367755544/index.html).
The burst signal was seen by all CGBM detectors.

The burst light curve shows a multi-peaked structure that starts
at T-139.5 sec, peaks at T+19.6 sec, and ends at T+43.6 sec.
The T90 and T50 durations measured by the SGM data are 106.2 +/- 71.3 sec
and 13.1 +/- 0.7 sec (40-1000 keV), respectively.

The ground-processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1367755544/

The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.


GRB_name: GRB230510B
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33763
SUBJECT: GRB 230510B: CALET Gamma-Ray Burst Monitor detection
DATE:    23/05/11 06:22:32 GMT
FROM:    Yuta Kawakubo at Louisiana State University <kawakubo1@lsu.edu>

P. S. Marrocchesi (U of Siena), A. Yoshida, T. Sakamoto,
S. Sugita (AGU), Y. Kawakubo (LSU), K. Yamaoka (Nagoya U),
S. Nakahira (RIKEN), Y. Asaoka (ICRR),
S. Torii, Y. Akaike, K. Kobayashi (Waseda U),
Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC),
M. L. Cherry (LSU), S. Ricciarini (U of Florence),
and the CALET collaboration:

The long GRB 230510B (Fermi GBM Final Real-time Localization: Fermi GBM team,
GCN Circ. 33759; MAXI/GSC detection: Nakajima et al., GCN Circ 33760) triggered
the CALET Gamma-ray Burst Monitor (CGBM) at 21:21:32.08 UTC on 10 May 2023
(http://cgbm.calet.jp/cgbm_trigger/flight/1367788853/index.html).
The burst signal was seen by all CGBM detectors.

The burst light curve shows a double-peaked structure that starts
at T-45.5 sec, peaks at T+23.4 sec, and ends at T+263.9 sec.
The T90 and T50 durations measured by the SGM data are 233.0 +/- 3.3 sec
and 168.5 +/- 0.8 sec (40-1000 keV), respectively.

The ground-processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1367788853/

The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.


GRB_name: GRB230510A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33764
SUBJECT: GRB 230510A: Gaoyazi/GOT optical upper limit
DATE:    23/05/11 07:17:27 GMT
FROM:    Dong Xu at NAOC/CAS <dxu@nao.cas.cn>

S.Q. Jiang, T.H. Lu, S.Y. Fu, X. Liu, D Xu (NAOC), Z.P. Zhu (NAOC, HUST), S.W. Luo, M.M. Yang, Z. K. Feng (GYZO, NAOC) report:

We observed the field of GRB 230510A detected by Swift (Eyles-Ferris et al., GCN 33752) and Fermi(Fermi GBM team, GCN 33751) with the GOT-0.5m telescope located at Gaoyazi, Xinjiang, China. Observations started at 18:48:27 UT on 2023-05-10, i.e., 6.7 hr after the Swift/BAT trigger, 40 x 90 s images were obtained in the Sloan r filter.

No optical source is detected in our stacked image at the enhanced XRT position (Evans et al., GCN 33756), down to a 3-sigma limiting magnitude r > 19.7 (AB) at 7.27 hr post-burst, calibrated with nearby PanSTARRS stars. The upper limit is consistent with our deeper detection at the Nanshan/NEXT (Jiang et al., GCN 33761).


GRB_name: GRB230510A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33766
SUBJECT: GRB 230510A: Fermi GBM detection
DATE:    23/05/11 08:36:05 GMT
FROM:    R. Hamburg at CNRS/IJCLab <rachel.k.hamburg@gmail.com>

C. Malacaria (ISSI) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 12:04:06.93 UT on 10 April 2023, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 230510A (trigger 705413051 / 230510503), which
was also detected by the Swift/BAT and Swift/XRT (Eyles-Ferris et al. 2023,
GCN 33752; Evans et al. 2023, GCN 33756). The GBM on-ground location is
consistent with the Swift position (GCN 33751).

The angle from the Fermi LAT boresight at the GBM trigger time is 14
degrees.

The GBM light curve shows a weaker peak followed about 100 s later
by a brighter peak, with a duration (T90) of about 177 s (50-300 keV).
The time-averaged spectrum from T0-4.1 s to T0+11.3 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.9 +/- 0.1 and
the cutoff energy, parameterized as Epeak, is 87 +/- 7 keV.
A Band function fits the spectrum equally well
with Epeak = 87 +/- 9 keV, alpha = -0.9 +/- 0.1 and beta = -3.8 +/- 3.2.

The event fluence (10-1000 keV) in this time interval is
(2.0 +/- 0.1)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+158 s in the 10-1000 keV band
is 12.4 +/- 0.4 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support
Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"


GRB_name: GRB230511A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33767
SUBJECT: GRB 230511A: Fermi GBM Final Real-time Localization
DATE:    23/05/11 11:25:42 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 11:15:05 UT on 11 May 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230511A (trigger 705496510.691274 / 230511469).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 145.0, Dec = 1.7 (J2000 degrees, equivalent to J2000 09h 39m, 1d 42'), with a statistical uncertainty of 16.0 degrees.

The angle from the Fermi LAT boresight is 35.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230511469/quicklook/glg_skymap_all_bn230511469.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230511469/quicklook/glg_healpix_all_bn230511469.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230511469/quicklook/glg_lc_medres34_bn230511469.gif


GRB_name: GRB230511B
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33769
SUBJECT: GRB 230511B: Fermi GBM Final Real-time Localization
DATE:    23/05/11 13:19:01 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 13:08:30 UT on 11 May 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230511B (trigger 705503315.71883 / 230511548).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 222.9, Dec = -7.7 (J2000 degrees, equivalent to J2000 14h 51m, -7d 42'), with a statistical uncertainty of 1.2 degrees.

The angle from the Fermi LAT boresight is 75.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230511548/quicklook/glg_skymap_all_bn230511548.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230511548/quicklook/glg_healpix_all_bn230511548.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230511548/quicklook/glg_lc_medres34_bn230511548.gif


GRB_name: GRB230511C
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33771
SUBJECT: GRB 230511C: Fermi GBM Final Localization
DATE:    23/05/11 14:23:20 GMT
FROM:    Joshua Wood at NASA/MSFC <joshua.r.wood@nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

"At 03:28:07.47 UT on 11 May 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230511C (trigger 705468492/230511145).

The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 262.8, Dec = -13.6 (J2000 degrees, equivalent to J2000 17h 31m, -13d 34'),
with a statistical uncertainty of 9.2 degrees.

The angle from the Fermi LAT boresight is 98 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230511145/quicklook/glg_skymap_all_bn230511145.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230511145/quicklook/glg_healpix_all_bn230511145.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230511145/quicklook/glg_lc_medres34_bn230511145.gif"


GRB_name: GRB230510B
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33772
SUBJECT: GRB 230510B: AstroSat CZTI detection
DATE:    23/05/11 15:03:27 GMT
FROM:    Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>

P K. Navaneeth (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long GRB 230510B which was also detected by Fermi (Fermi GBM Team, GCN Circ. 33759), MAXI/GSC (Nakajima et al., GCN Circ. 33760), and CALET (Marrocchesi et al., GCN Circ. 33763).

The source was detected in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2023-05-10 21:21:52.50 UTC. The measured peak count rate associated with the burst is 98 (+43, -2) counts/s above the background in the combined data of three quadrants (out of four), with a total of 4971 (+1144, -1220) counts. The local mean background count rate was 313 (+1, -1) counts/s. Using cumulative rates, we measure a T90 of 270 (+36, -58) s.

The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range.The light curve showed multiple peaks of emission with the strongest peak at 2023-05-10 21:21:52.50 UTC. The measured peak count rate associated with the burst is 316 (+77, -19) counts/s above the background in the combined data of all quadrants, with a total of 11559 (+2752, -3027) counts. The local mean background count rate was 1315 (+3, -3) counts/s. We measure a T90 of 202 (+36, -10) s from the cumulative Veto light curve.

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb


GRB_name: GRB230510A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33774
SUBJECT: GRB 230510A: Swift/UVOT Observations
DATE:    23/05/11 22:28:10 GMT
FROM:    Alexander Belles at PSU <aub1461@psu.edu>

A. Belles (PSU) and R. A. J. Eyles-Ferris (U Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 230510A
72 s after the BAT trigger (Eyles-Ferris et al., GCN Circ. 33752).
A source consistent with the XRT position (Evans et al., GCN Circ. 33756)
is detected in the initial UVOT exposures.
Preliminary detections and 3-sigma upper limits using the UVOT photometric
system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter      T_start(s)    T_stop(s)       Exp(s)           Mag
wh_FC               72          222          150      18.90+/-0.10
u_FC               284          318           34      18.09+/-0.32
wh                4413         4613          200      19.33+/-0.11
v                 4824         5024          200      18.97+/-0.32
b                 4209         5690          241      19.31+/-0.17
u                 5439         5638          199      19.10+/-0.24
w1                5234         5434          200      19.30+/-0.34
m2                5029         5228          199            >19.21
w2                4619         4819          200            >19.45

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.144 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB230511D
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33775
SUBJECT: GRB 230511D: Fermi GBM Final Real-time Localization
DATE:    23/05/11 22:50:51 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely SHORT GRB

At 22:40:18 UT on 11 May 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230511D (trigger 705537623.19843 / 230511945).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 237.5, Dec = -17.4 (J2000 degrees, equivalent to J2000 15h 50m, -17d 23'), with a statistical uncertainty of 21.7 degrees.

The angle from the Fermi LAT boresight is 79.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230511945/quicklook/glg_skymap_all_bn230511945.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230511945/quicklook/glg_healpix_all_bn230511945.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230511945/quicklook/glg_lc_medres34_bn230511945.gif


GRB_name: GRB230510A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33776
SUBJECT: GRB 230510A: LCOGT Optical Upper Limit
DATE:    23/05/12 00:51:38 GMT
FROM:    Robert Strausbaugh at University of Minnesota <rstrausb@umn.edu>

R. Strausbaugh (University of Minnesota), A. Cucchiara (NASA) report on

behalf of a larger collaboration:

We observed the GRB 230510A (Eyles-Ferris et al., GCN 33752) field
with the LCOGT
1-meter Sinistro instrument at the Teide Observatory, Tenerife site, on May
11, from 03:03 to 03:36 UT (corresponding to 14.95 to 15.50 hours from the
GRB trigger time) with the SDSS r and i filters.

We performed a series of 3x300s exposures in each band.  We do not detect a
source within the Swift-XRT enhanced error region (Evans et al., GCN 33756)
in either band, consistent with fading from the optical afterglow candidate
(Jiang et al., GCN 33761).

The following upper limits are calculated using the PanSTARRS catalog as
reference:


r > 21.5

i > 19.8

These magnitudes are not corrected for galactic extinction.


GRB_name: GRB230510A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33777
SUBJECT: GRB 230510A: GIT optical upper limits
DATE:    23/05/12 11:26:15 GMT
FROM:    Vishwajeet Swain at IIT Bombay <vishwajeet.s@iitb.ac.in>

V. Swain (IITB), A. Salgundi (IITB), H. Kumar (IITB), V. Bhalerao (IITB), G.C. Anupama(IIA), S. Barway (IIA) and K. Angail (IAO) report on behalf of the GIT team: 

We observed the field of GRB 230510A detected by Fermi (Fermi GBM team, GCN 33751, 33766) and Swift (Eyles-Ferris et al., GCN 33752) with 0.7m GROWTH-India Telescope (GIT). GIT automatically triggered at 19:35:39 UT, i.e., 7.5 hours after the Fermi GBM trigger. We obtained 3 frames of 300s each in the r' band. We search individual images and the stacked image for an afterglow, at the position reported by P.A. Evans et al. (GCN #33756). We do not detect the optical afterglow emission that was detected by S.Q. Jiang et al., (GCN #33761). Our upper limits on the magnitude of the afterglow are:

-------------------------------------------------------------------------------------------------------------------      
           JD (mid)           | T_mid-T0(hrs) | Exposure (sec)   | Filter | Lim_mag (5-sigma) |
------------------------------------------------------------------------------------------------------------------- 
 2460075.3164274      |         7.52        |          300            |    r'    |          > 18.77            |
 2460075.32027526    |         7.62        |          300            |    r'    |          > 18.81            |
 2460075.32398713    |         7.71        |          300            |    r'    |          > 18.90            | 
 2460075.320207265  |    7.61 (mid)    | 3x300 (stacked) |    r'    |          > 19.87            |
------------------------------------------------------------------------------------------------------------------

The results are consistent with other afterglow observations reported by S.Q. Jiang et al., GCN #33761; S.Q. Jiang et al., GCN #33764; A. Belles et al., GCN #33774; R. Strausbaugh at al., GCN #33776. The magnitudes are calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction.

The GROWTH India Telescope (GIT; Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/.


GRB_name: GRB230512A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33778
SUBJECT: GRB 230512A: Fermi GBM Final Localization
DATE:    23/05/12 11:59:08 GMT
FROM:    R. Hamburg at CNRS/IJCLab <rachel.k.hamburg@gmail.com>

The Fermi GBM team reports the detection of a Short Bright GRB.

At 06:27:45 UT on 12 May 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230512A (trigger 705565670/230512269).

The on-ground calculated location, using the Fermi GBM trigger data, is RA
= 277.62, Dec = +53.87 (J2000 degrees, equivalent to J2000 18h 30m, +53d
53'), with a statistical uncertainty of 1 degree.

The angle from the Fermi LAT boresight is 26 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230512269/quicklook/glg_skymap_all_bn230512269.png

The HEALPix FITS file, including the estimated localization systematic, can
be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230512269/quicklook/glg_healpix_all_bn230512269.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230512269/quicklook/glg_lc_medres34_bn230512269.gif


GRB_name: GRB230512A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33779
SUBJECT: GRB 230512A: AstroSat CZTI detection
DATE:    23/05/12 14:20:03 GMT
FROM:    Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>

P K. Navaneeth (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of GRB 230512A which was also detected by Fermi GBM (Fermi GBM Team, GCN Circ. 33778).

The source was clearly detected in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2023-05-12 06:27:47.85 UTC. The measured peak count rate associated with the burst is 2471 (+338, -103) counts/s above the background in the combined data of all quadrants, with a total of 3279 (+219, -231) counts. The local mean background count rate was 490 (+10, -12) counts/s. Using cumulative rates, we measure a T90 of 2.44 (+0.17, -0.13) s. In the preliminary analysis, we find 317 Compton events associated with this event.

The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2023-05-12 06:27:47.85 UTC. The measured peak count rate associated with the burst is 2735 (+109, -115) counts/s above the background in the combined data of all quadrants, with a total of 6183 (+356, -346) counts. The local mean background count rate was 1667 (+6, -9) counts/s. We measure a T90 of 2.82 (+2.02, -0.27) s from the cumulative Veto light curve.

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb


GRB_name: GRB230512A
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33780
SUBJECT: GRB 230512A: Fermi-LAT detection
DATE:    23/05/12 18:34:10 GMT
FROM:    N. Di Lalla at Stanford University <niccolo.dilalla@stanford.edu>

D. J. Maheso (Johannesburg Univ.), N. Di Lalla (Stanford Univ.), Khalil T. (Johannesburg Univ.), E. Bissaldi (Politecnico and INFN Bari), N. Omodei (Stanford Univ.), D. Kocevski (NASA/MSFC) and D. Horan (IN2P3/CNRS) report on behalf of the Fermi-LAT Collaboration:

At 06:27:45.41 on May 12, 2023, Fermi-LAT detected high-energy emission from GRB 230512A, which was also detected by Fermi-GBM (trigger 705565670/230512269, GCN 33778) and AstroSat (GCN 33779).

The best LAT on-ground location is found to be

RA, Dec = 295.4, 38.4 (degrees, J2000)

with an error radius of 0.3 deg (90% containment, statistical error only).
This was 45 deg from the LAT boresight at the time of the trigger.

The data from the Fermi-LAT show a significant increase in the event rate that is spatially and temporally correlated with the GBM emission with high significance.
The 100 MeV - 1 GeV photon flux in the time interval 0-300 s after the GBM trigger is (1.0 Â± 0.3) E-05 ph/cm2/s. The estimated integrated photon index above 100 MeV is -2.15 Â± 0.3.

The highest-energy photon is a 1.7 GeV event with 99% probability which is observed 84 seconds after the GBM trigger.

A Swift ToO has been approved for this burst.

The Fermi-LAT point of contact for this burst is Dimakatso Maheso (d.j.maheso@gmail.com <mailto:xxxx@xxx.xxx>)

The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.


GRB_name: GRB230512A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33781
SUBJECT: GRB 230512A: Tiled Swift observations
DATE:    23/05/12 19:05:37 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>


P. A. Evans (U. Leicester) reports on behalf of the Swift team:

Swift has initiated a series of observations, tiled on the sky, of the
Fermi/LAT GRB 230512A. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00111

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. The probability of finding
serendipitous sources, unrelated to the Fermi/LAT event is high: any X-ray source
considered to be a probable afterglow candidate will be reported via a GCN Circular
after manual consideration.

Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).

This circular is an official product of the Swift-XRT team.


GRB_name: GRB230511D
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33782
SUBJECT: GRB 230511D: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 705537623)
DATE:    23/05/12 20:19:22 GMT
FROM:    Viraj Karambelkar at Indian Inst of Tech,Bombay <karambelkarvraj21197@gmail.com>

Viraj Karambelkar, Robert Stein (Caltech), Simeon Reusch (DESY), Theophile
du Laz (Caltech), Aswin Suresh, Harsh Kumar, Vishwajeet Swain, Varun
Bhalerao (IIT Bombay), Jannis Necker (DESY), Tomas Ahumada (Caltech) on
behalf of the Zwicky Transient Facility Collaboration.

We observed the localization region of Fermi GRB 230511D (trigger
705537623). We obtained a total of 75 images covering ztfg, ztfr bands for
a total of 8750 seconds. The observations covered 951.5 square degrees
beginning at 2023-05-12T04:02:10.000 (5 hours after the burst trigger time)
corresponding to ~60% of the probability enclosed in the localization
region. The median depth of the observations was ~21.3 mag. Our
observations cover the part of the localization that is northwards of -24
degrees declination. Any candidate-counterparts will be announced in
forthcoming GCNs.


GRB_name: GRB230430A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33783
SUBJECT: GRB 230430A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 704533643)
DATE:    23/05/12 20:20:45 GMT
FROM:    Tomas Ahumada at U. of Maryland <tahumada@astro.umd.edu>

Tomas Ahumada (CIT), Shreya Anand (CIT), Viraj Karambelkar (CIT), Robert
Stein (CIT), Theophile du Laz (CIT), Michael Coughlin (UMN), Mansi Kasliwal
(CIT), Simeon Reusch (DESY), Jannis Necker (DESY) report on behalf of the
ZTF collaboration:

We observed the localization region of the short GRB 230430A (trigger
704533643) detected by the Gamma-Ray Burst Monitor (GBM) on the Fermi
satellite with the Palomar 48 inch telescope equipped with the 47 square
degree Zwicky Transient Facility (ZTF; Bellm et al., 2019; Graham et al.,
2019) camera. We obtained a series of g- and r-band images covering about
132.4 square degrees beginning at 2023-05-01T04:45:43.004 (~20 hours after
the burst trigger time) corresponding to ~93% of the probability enclosed
in the intersection between the GBM (GCN 33713) and the preliminary IPN
region. Our observations contain the final IPN region (GCN 33718).
Exposures reached a median depth of 21.5 mag in the g-band and 21.5 mag in
the r-band. No potential counterparts were found.

ZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC,
USA, WIS, Israel; OKC, Sweden; JSI/UMd, USA; U Washington, USA; DESY,
Germany; MOST, Taiwan; UW Milwaukee, USA; LANL USA; Tokyo Tech, Japan;
IITB, India; IIA, India; LJMU, UK; TTU, USA; SDSU, USA and USyd, Australia.
ZTF acknowledges the generous support of the NSF under AST MSIP Grant No
1440341.
GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949.
Alert distribution service provided by DIRAC@UW (Patterson et al. 2019).
Alert database searches are done by AMPEL (Nordin et al. 2019) and Kowalski
(Duev et al. 2019). GROWTH India telescope is located at the Indian
Astronomical Observatory (Hanle), operated by the Indian Institute of
Astrophysics (IIA). GROWTH-India project is supported by SERB and
administered by IUSSTF, under grant number IUSSTF/PIRE
Program/GROWTH/2015-16 and IUCAA.
<https://hackmd.io/JGjJMLLsSPW4EwSesjMTdA#>


-- 
TomÃ¡s Ahumada (he/him)
Ph.D. Candidate
Department of Astronomy
University of Maryland, College Park
NASA <tomas.f.ahumdamena@nasa.gov> Goddard Space Flight Center, Code 661
B.Sc. Astronomy, Pontificia Universidad CatÃ³lica de Chile


GRB_name: GRB230512A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33784
SUBJECT: GRB 230512A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 705565670)
DATE:    23/05/12 20:21:39 GMT
FROM:    Tomas Ahumada at U. of Maryland <tahumada@astro.umd.edu>

Tomas Ahumada (CIT), Harsh Kumar (IITB),  Viraj Karambelkar (CIT), Robert
Stein (CIT), Theophile du Laz (CIT), Igor Andreoni (UMD), Michael Coughlin
(UMN), Mansi Kasliwal (CIT), Simeon Reusch (DESY), Jannis Necker (DESY),
Shreya Anand (CIT), report on behalf of the ZTF collaboration:

We observed the localization region of the short bright GRB 230512A
(trigger 705565670, GCN 33778) detected by the Gamma-Ray Burst Monitor
(GBM) on the Fermi satellite with the Palomar 48 inch telescope equipped
with the 47 square degree Zwicky Transient Facility (ZTF; Bellm et al.,
2019; Graham et al., 2019) camera. ZTF covered 597.8 square degrees
corresponding to ~86% of the probability enclosed in the localization
region (GCN 33778), beginning 2 hours after the burst trigger time.
Exposures reached a median depth of 21 mag in the g-band and 20.9 mag in
the r-band.

Two sources were found within the 95% localization region, although all are
outside the 90% credible level. These are likely unrelated as they fall
outside the LAT localization circulated on GCN 33780:


+--------------+---------+----------+---------+------------+------------+------------+
| id           | alias   |       ra |     dec | mjd        | mag
 |filter      |
|--------------+---------+----------+---------+------------|------------+------------|
| ZTF23aajfoed | AT 2023ibn  | 295.8501 | 51.5420 | 60076.4041 | 18.89Â±0.08
| g          |
| ZTF23aajfilx | AT 2023ibo  | 267.5692 | 40.7678 | 60076.3839 | 20.22Â±0.19
| g          |
+--------------+---------+----------+---------+------------+------------+------------+


ZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC,
USA, WIS, Israel; OKC, Sweden; JSI/UMd, USA; U Washington, USA; DESY,
Germany; MOST, Taiwan; UW Milwaukee, USA; LANL USA; Tokyo Tech, Japan;
IITB, India; IIA, India; LJMU, UK; TTU, USA; SDSU, USA and USyd, Australia.
ZTF acknowledges the generous support of the NSF under AST MSIP Grant No
1440341.
GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949.
Alert distribution service provided by DIRAC@UW (Patterson et al. 2019).
Alert database searches are done by AMPEL (Nordin et al. 2019) and Kowalski
(Duev et al. 2019). GROWTH India telescope is located at the Indian
Astronomical Observatory (Hanle), operated by the Indian Institute of
Astrophysics (IIA). GROWTH-India project is supported by SERB and
administered by IUSSTF, under grant number IUSSTF/PIRE
Program/GROWTH/2015-16 and IUCAA.


-- 
TomÃ¡s Ahumada (he/him)
Ph.D. Candidate
Department of Astronomy
University of Maryland, College Park
NASA <tomas.f.ahumdamena@nasa.gov> Goddard Space Flight Center, Code 661
B.Sc. Astronomy, Pontificia Universidad CatÃ³lica de Chile


GRB_name: GRB230512A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33785
SUBJECT: GRB 230512A: Fermi GBM detection
DATE:    23/05/12 22:33:49 GMT
FROM:    Oliver J Roberts at USRA/NASA <oliver.roberts@nasa.gov>

S. Bala (USRA), O.J. Roberts (USRA/NASA-MSFC), B. Mailyan (Florida Tech) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 06:27:45.00 UT on 12 May 2023, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 230512A (trigger 705565670 /230512269), which was also
detected by the Fermi/LAT (D. J. Maheso et al. 2023, GCN 33780).

The Fermi GBM Final Real-time Localization (GCN 33778) is consistent with the LAT position.

The angle from the Fermi LAT boresight at the GBM trigger time is 45 degrees.

The GBM light curve consists of multiple short peaks
with a duration (T90) of about 3 s (50-300 keV).
The time-averaged spectrum from T0-0.064 s to T0+2.944 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.67 +/- 0.02 and
the cutoff energy, parameterized as Epeak, is 1344 +/- 69 keV

The event fluence (10-1000 keV) in this time interval is
(1.33 +/- 0.02)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+1.54 s in the 10-1000 keV band
is 16.8 +/- 0.3 ph/s/cm^2.

A Band function fits the spectrum equally well
with Epeak= 1215 +/- 79 keV, alpha = -0.65 +/- 0.03 and beta = -2.7 +/- 0.2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"


GRB_name: GRB230512A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33786
SUBJECT: GRB 230512A: GIT optical follow-up ZTF candidates
DATE:    23/05/12 22:45:11 GMT
FROM:    Vishwajeet Swain at IIT Bombay <vishwajeet.s@iitb.ac.in>

H. Kumar (IITB), V. Swain (IITB), A. Salgundi (IITB), V. Bhalerao (IITB), G.C. Anupama (IIA), S. Barway (IIA) and K. Angail (IAO) report on behalf of the GIT team:

We observed ZTF23aajfoed and ZTF23aajfilx detected by ZTF in localization region of the short GRB 230512A (Fermi GBM team, GCN 33778), with the 0.7m GROWTH-India Telescope (GIT). The observations started at 17:42:28 UT on 2023-05-12 for ZTF23aajfoed and at 17:08:25 for ZTF23aajfilx, roughly 11 hours after the Fermi GBM trigger. We obtained multiple 300s exposures in the g' and r' filters. We clearly detected the candidates at position reported by T. Ahumada et al., GCN 33784. The photometric results are follow as:

------------------------------------------------------------------------------------
Target | mjd (mid) | Filter | Total Exposure (s) | Magnitude (AB) |

-------------------------------------------------------------------------------------

 ZTF23aajfoed | 60076.741640 | r' | 300 | 18.87 +/- 0.06 |
 ZTF23aajfoed | 60076.745515 | g' | 300 | 18.84 +/- 0.07 |
 
 ZTF23aajfilx | 60076.717906 | r' | 300 | 20.16 +/- 0.07 |
 ZTF23aajfilx | 60076.745515 | g' | 300 | 20.23 +/- 0.07 |


-----------------------------------------------------------------------------------

A comparison of GIT and ZTF observations suggests that both the targets are not evolving rapidly, indicating that they are unlikely to be GRB afterglows. The magnitudes are calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction. 

The GROWTH India Telescope (GIT; Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/.


GRB_name: GRB230512A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33789
SUBJECT: GRB 230512A: Swift-XRT observations
DATE:    23/05/13 08:06:19 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

J.P. Osborne (U. Leicester), A. Melandri (INAF-OAR), T. Sbarrato
(INAF-OAB), P. D'Avanzo (INAF-OAB), J.A. Kennea (PSU), A. Tohuvavohu
(U. Toronto), D.N. Burrows (PSU), K.L. Page (U. Leicester), A.P.
Beardmore (U. Leicester) and P.A. Evans (U. Leicester) report on behalf
of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Fermi/LAT-detected burst GRB 230512A in a series of observations tiled
on the sky. The total exposure time is 4.9 ks, distributed over 4
tiles; the maximum exposure at a single sky location was 2.3 ks. The
data were collected between T0+45.5 ks and T0+57.3 ks, and are entirely
in Photon Counting (PC) mode. 

Nine uncatalogued X-ray sources have been detected, however none of
them is above the RASS limit or shows definitive signs of fading.
Therefore, at the present time we cannot identify which, if any, is the
afterglow. Details of these sources are given below:

Source 1:
  RA (J2000):  295.4803  =  19:41:55.26
  Dec (J2000): +38.6649  =  +38:39:53.6
  Error: 4.2 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: (8.8 [+3.9, -3.0])e-3 ct s^-1   
  Distance: 980 arcsec from Fermi/LAT position.
  Flux: (5.1 [+2.2, -1.8])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 3:
  RA (J2000):  295.5430  =  19:42:10.33
  Dec (J2000): +38.7526  =  +38:45:09.4
  Error: 5.5 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: 0.0176 [+0.0056, -0.0047] ct s^-1   
  Distance: 1331 arcsec from Fermi/LAT position.
  Flux: (3.57 [+1.13, -0.95])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 5:
  RA (J2000):  295.2060  =  19:40:49.43
  Dec (J2000): +38.4686  =  +38:28:07.1
  Error: 6.2 arcsec (radius, 90% conf.)
  Count-rate: 0.0105 [+0.0042, -0.0034] ct s^-1   
  Distance: 600 arcsec from Fermi/LAT position.

Source 6:
  RA (J2000):  295.7616  =  19:43:2.79
  Dec (J2000): +38.3644  =  +38:21:51.9
  Error: 3.9 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: (6.7 [+3.5, -2.6])e-3 ct s^-1   
  Distance: 1028 arcsec from Fermi/LAT position.

Source 7:
  RA (J2000):  295.0895  =  19:40:21.48
  Dec (J2000): +38.4348  =  +38:26:05.5
  Error: 6.8 arcsec (radius, 90% conf.)
  Count-rate: (5.4 [+3.3, -2.4])e-3 ct s^-1   
  Distance: 884 arcsec from Fermi/LAT position.

Source 8:
  RA (J2000):  295.3130  =  19:41:15.11
  Dec (J2000): +38.4565  =  +38:27:23.3
  Error: 5.1 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: (8.7 [+4.1, -3.2])e-3 ct s^-1   
  Distance: 318 arcsec from Fermi/LAT position.

Source 9:
  RA (J2000):  295.2484  =  19:40:59.62
  Dec (J2000): +38.1016  =  +38:06:05.7
  Error: 7.7 arcsec (radius, 90% conf.)
  Count-rate: (5.5 [+3.1, -2.3])e-3 ct s^-1   
  Distance: 1156 arcsec from Fermi/LAT position.

Source 10:
  RA (J2000):  295.1589  =  19:40:38.13
  Dec (J2000): +38.4685  =  +38:28:06.6
  Error: 6.1 arcsec (radius, 90% conf.)
  Count-rate: (9.8 [+5.8, -4.3])e-3 ct s^-1   
  Distance: 723 arcsec from Fermi/LAT position.

Source 11:
  RA (J2000):  295.2125  =  19:40:50.99
  Dec (J2000): +38.0868  =  +38:05:12.5
  Error: 4.5 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: (9.5 [+4.1, -3.2])e-3 ct s^-1   
  Distance: 1245 arcsec from Fermi/LAT position.
  Flux: (3.3 [+1.4, -1.1])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Two catalogued sources were also detected.

The results of the XRT-team automatic analysis of the tiled XRT
observations, including a position-specific upper limit calculator, are
available at https://www.swift.ac.uk/xrt_products/TILED_GRB00111.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB230510A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33790
SUBJECT: GRB 230510A: OHP/T193 and OHP/T120 optical observations
DATE:    23/05/13 08:39:57 GMT
FROM:    Damien Turpin at CEA-Saclay <dturpin-astro@hotmail.com>

B. Schneider (MIT), C. Adami (LAM/Pytheas/AMU), J. T. Palmerio (GEPI, 
Obs. de Paris), S. Basa (LAM), E. Le Floc'h, D. GÃ¶tz (CEA Paris-Saclay), 
S. D. Vergani (GEPI, Obs. de Paris), C. Barthelemy, Q. Desvigne, 
J. Latour (AMU), D. Turpin (CEA Paris-Saclay), report on behalf of a 
larger collaboration:

We observed the field of GRB 230510A (Fermi GBM team, GCN 33751; Eyles-Ferris 
et al., GCN 33752) using the T193cm and T120cm telescopes at Observatoire de 
Haute-Provence (France) respectively equipped with the MISTRAL spectro-imager
and the T120 CCD camera. A total of 8 exposures were obtained in the imaging 
mode of MISTRAL in the r-band filter (6x600s + 2x300s) and 50 exposures 
were obtained with the T120 CCD camera in the r-band filter (50x90s). 
Observations were made from 2023 11 May 01:24:26 UT to 2023 11 May 03:00:47 UT 
(mid time ~13.2h after trigger).

In the combined frames, we detect a faint source consistent with the 
X-ray afterglow position reported by Evans et al. (GCN 33756) and 
with the optical afterglow position reported by Jiang et al. (GCN 33761). 
The source is detected by both instruments at the same position.

Combining the MISTRAL and T120 images, we measured a magnitude of 
r = 21.8 +/- 0.2, in agreement with the value determined individually for 
each instrument. The faintest PanStarr DR1 object detected at 3 sigma 
in the combined image is at r = 22. The photometric calibration was 
performed using nearby stars from the PS1 catalog and the magnitude 
is not corrected for Galactic extinction.

We acknowledge the excellent support from Observatoire de Haute-Provence, 
in particular Jean Balcaen for the MISTRAL observations, Yoann Degot-Longhi, 
Stephane Favard, Luc Favre, and Christelle Eyraud for the T120 observations.


GRB_name: GRB230513A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33793
SUBJECT: GRB 230513A: Fermi GBM Final Real-time Localization
DATE:    23/05/13 22:27:50 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely SHORT GRB

At 22:17:19 UT on 13 May 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230513A (trigger 705709044.428824 / 230513929).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 160.7, Dec = 27.9 (J2000 degrees, equivalent to J2000 10h 42m, 27d 53'), with a statistical uncertainty of 7.5 degrees.

The angle from the Fermi LAT boresight is 89.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230513929/quicklook/glg_skymap_all_bn230513929.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230513929/quicklook/glg_healpix_all_bn230513929.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230513929/quicklook/glg_lc_medres34_bn230513929.gif


GRB_name: GRB230510A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33794
SUBJECT: GRB 230510A: GRBAlpha detection
DATE:    23/05/14 08:25:50 GMT
FROM:    Marianna DafÄÃ­kovÃ¡ at Masaryk University <500025@mail.muni.cz>

M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory), N. Werner (Masaryk U.), M. Ohno, H. Takahashi (Hiroshima U.), L. Meszaros, B. Csak (Konkoly Observatory), N. Husarikova, F. Munz , M. Topinka, M. Kolar, J.-P. Breuer, F. Hroch (Masaryk U.), T. Urbanec, M. Kasal,  A. Povalac (Brno U. of Technology), J. Hudec, J. Kapus, M. Frajt (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix s.r.o), M. Smelko, P. Hanak, P. Lipovsky (Technical U. of Kosice), G. Galgoczi (Wigner Research Center/Eotvos U.), Y. Uchida, H. Poon, H. Matake (Hiroshima U.), N. Uchida (ISAS/JAXA), T. Bozoki (Eotvos U.), G. Dalya (Eotvos U.), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), G. Friss (Eotvos U.), Y. Fukazawa, K. Hirose (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), K. Kapas (Eotvos U.), L. L. Kiss (Konkoly Observatory),  T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), J. Takatsy (Eotvos U.), K. Torigoe (Hiroshima U.), N. Kogiso, M. Yoneyama (Osaka Metropolitan U.), M. Moritaki (U. Tokyo), T. Kano (U. Michigan) -- the GRBAlpha collaboration.

The long-duration GRB 230510A (Fermi/GBM detection: GCN 33751; Swift/BAT detection: GCN 33752; CALET/CGBM detection: GCN 33762; Wind/Konus detection at 2023-05-10 12:06:42.814 UT; INTEGRAL/SPI-ACS detection at 2023-05-10 12:06:43 UT) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023; arXiv:2302.10048).

The detection was confirmed at the peak time 2023-05-10 12:06:31 UTC. The T90 duration measured by GRBAlpha is 24 s and the overall significance during T90 reaches 6.6 sigma in the 120-400 keV band.

The light curve obtained by GRBAlpha is available here: 
https://grbalpha.konkoly.hu/static/share/GRB230510A_GCN.pdf

All GRBAlpha detections are listed at: https://monoceros.physics.muni.cz/hea/GRBAlpha/ 
GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume. 


GRB_name: GRB230512A
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33795
SUBJECT: GRB 230512A: GRBAlpha detection
DATE:    23/05/14 08:29:43 GMT
FROM:    Marianna DafÄÃ­kovÃ¡ at Masaryk University <500025@mail.muni.cz>

M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory), N. Werner (Masaryk U.), M. Ohno, H. Takahashi (Hiroshima U.), L. Meszaros, B. Csak (Konkoly Observatory), N. Husarikova, F. Munz , M. Topinka, M. Kolar, J.-P. Breuer, F. Hroch (Masaryk U.), T. Urbanec, M. Kasal,  A. Povalac (Brno U. of Technology), J. Hudec, J. Kapus, M. Frajt (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix s.r.o), M. Smelko, P. Hanak, P. Lipovsky (Technical U. of Kosice), G. Galgoczi (Wigner Research Center/Eotvos U.), Y. Uchida, H. Poon, H. Matake (Hiroshima U.), N. Uchida (ISAS/JAXA), T. Bozoki (Eotvos U.), G. Dalya (Eotvos U.), yyT. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), G. Friss (Eotvos U.), Y. Fukazawa, K. Hirose (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), K. Kapas (Eotvos U.), L. L. Kiss (Konkoly Observatory),  T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), J. Takatsy (Eotvos U.), K. Torigoe (Hiroshima U.), N. Kogiso, M. Yoneyama (Osaka Metropolitan U.), M. Moritaki (U. Tokyo), T. Kano (U. Michigan) -- the GRBAlpha collaboration.

The GRB 230512A (Fermi/GBM detection: GCN 33778; Fermi/LAT detection: GCN 33780; AstroSat detection: GCN 33779) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023; arXiv:2302.10048).

The detection was confirmed at the peak time 2023-05-12 06:27:47 UTC. The T90 duration measured by GRBAlpha is 4 s and the overall significance during T90 reaches 11 sigma.

The light curve obtained by GRBAlpha is available here: 
https://grbalpha.konkoly.hu/static/share/GRB230512A_GCN.pdf

All GRBAlpha detections are listed at: https://monoceros.physics.muni.cz/hea/GRBAlpha/ 
GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume. 


GRB_name: GRB230512A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33796
SUBJECT: GRB 230512A: Kitab possible afterglow candidate
DATE:    23/05/14 12:41:26 GMT
FROM:    Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>

S. Belkin (IKI), A. Schmalz (KIAM), A. Pozanenko (IKI), N. Pankov (HSE), Sh. Ehgamberdiev (UBAI) report on behalf of IKI-GRB-FuN:

We observed the field of Fermi LAT localization (Maheso et al., GCN  33780) of short bright GRB 230512A (Fermi GBM team, GCN 33778; detected also by AstroSat GCN 33779, and GRBAlpha GCN 33795) with Kitab RC-36  telescope.  Observation  in Clear filter started on May, 12  (UT) 19:17:32 and continued on May, 13  (UT) 20:49:59. We cover XRT sources ## 2,4,5,7,8,9,10,11 (Osborne et al., GCN 33789). 
Within the XRT #5 error circle, we detected a possible optical source on May 12 and did not detect the source on May 13. The source is also absent in PS1 catalog. The coordinate of the source are 
(J2000) 19:40:49.49 +38:28:07.4  
with uncertainness of 0.5 arcsec in both coordinates. The nearest PS object is 2.5 arcses East with r'=22.14.

Preliminary photometry of the source in combined images is following

 Date,      UT start, t-T0,   Exp.,  Filter, OT,    Err,  UL(3 sigma)
                    (mid, days)

2023-05-12  19:17:32 0.57624  120*60  Clear  19.43  0.25   19.7
2023-05-13  20:49:59 1.64044  120*60  Clear  n/d    n/d    20.0

The photometry is based on nearby USNO-B1.0 stars, R2 magnitude and not corrected for Galaxy extinction.

USNO-B1.0 stars
RA Dec R2
19:40:50.8094400 +38:29:37.881600 14.55
19:40:53.3748000 +38:29:06.702000 15.30
19:40:46.4635200 +38:06:31.770000 14.15
19:41:16.4054400 +38:09:39.092400 15.80

Taking photometry in the first epoch and an upper limit on the second epoch the index of power law decay is less than -0.5.


GRB_name: GRB230512A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33797
SUBJECT: GRB 230512A: GIT non detection of afterglow candidate
DATE:    23/05/14 16:41:15 GMT
FROM:    Vishwajeet Swain at IIT Bombay <vishwajeet.s@iitb.ac.in>

V. Swain (IITB), H. Kumar (IITB), A. Salgundi (IITB), V. Bhalerao (IITB), G.C. Anupama (IIA), S. Barway (IIA) and K. Angail (IAO) report on behalf of the GIT team:

We observed the region of short GRB 230512A (Fermi GBM team, GCN 33778 and D. J. Maheso et al., GCN 33780), with the 0.7m GROWTH-India Telescope (GIT) covering the position of afterglow detected by S. Belkin et al., GCN 33796, . The observations started at 20:41:30 UT on 2023-05-12, 14.22 hours after the Fermi GBM trigger and 1.4 hours after the commencement of Kitab RC-36 observations (Belkin et al., GCN #33796). We obtained two exposures of 400s each in the r' band, coincidentally overlapping with the end of their first epoch. We later imaged the field in the g' band as well, with 2x400s exposures. We search individual images and the stacked image for an afterglow, but find no afterglow candidates. In particular, we do not detect the optical afterglow emission reported by S. Belkin et al., GCN 33796, despite our images having sufficient depth. Our upper limits are as follows:

-----------------------------------------------------------------------------
JD (mid) | T_mid-T0(hrs) |T_mid - T(Kitab)|Filter | Total Exposure (s) | Lim_mag (5-sigma) |

-----------------------------------------------------------------------------

 2460077.364615665 | 14.28 | 1.46 | r' | 2 X 400 (stacked) | >20.39 |
 2460077.43835897 | 15.88 | 3.05 | g' | 2 x 400 (stacked) | >21.08 |


----------------------------------------------------------------------------

We note that there is no known minor planet at this location in MPC. The magnitudes are calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction.

The GROWTH India Telescope (GIT; Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/.


GRB_name: GRB230512A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33798
SUBJECT: GRB 230512A: Liverpool Telescope observations
DATE:    23/05/14 17:03:28 GMT
FROM:    Ben Gompertz at U of Birmingham <b.gompertz@bham.ac.uk>

B. P. Gompertz (U. Birmingham), D. B. Malesani (U. Radboud and DAWN/NBI) and A. J. Levan (U. Radboud) report:

We tiled part of the LAT localisation (Maheso et al., GCN 33780) of GRB 230512A (Fermi GBM Team, GCN 33778; Navaneeth et al., GCN 33779; Dafcikova et al., GCN 33795) with the IO:O optical camera on the 2m robotic Liverpool Telescope. XRT source 5 (Osborne et al., GCN 33789) was covered by an observation beginning on May 13, 2023 at 03:10:22 UT and consisting of a series of 6x150 s exposures in the SDSS r' filter.

We detect no source at the position of the candidate optical counterpart reported by Kitab (Belkin et al., GCN 33796) to a 3-sigma limit of râ€™ > 22.15, ~7.5 hours after the reported detection. We also detect the PS1 source at a magnitude consistent with the catalogued value.

No other candidate optical counterparts have been identified in our imaging, which also covers XRT sources 8 and 10, to typical limits of r' > 22. Analysis is ongoing.

Magnitudes are in the AB system, calibrated against nearby PS1 stars (Chambers et al., 2016), and are not corrected for extinction along the line of sight.


GRB_name: GRB230512A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33799
SUBJECT: GRB 230512A: Zwicky Transient Facility non-detection of GRB afterglow candidate
DATE:    23/05/14 17:10:39 GMT
FROM:    Tomas Ahumada at U. of Maryland <tahumada@astro.umd.edu>

Tomas Ahumada (CIT), Michael Coughlin (UMN), Igor Andreoni (UMD), Varun
Bhalerao (IITB) on behalf of the ZTF collaboration:

We analyze the ZTF images containing the afterglow candidate (Belkin et
al., GCN Circ. 33796) and no sources were found up to the following limits:

UTC observation , t-t0 , filter, upper limit
2023-05-13 06:33:14, 1.003 , r , 21.02 mag
2023-05-13 06:25:09, 0.998 , g , 20.83 mag


ZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC,
USA, WIS, Israel; OKC, Sweden; JSI/UMd, USA; U Washington, USA; DESY,
Germany; MOST, Taiwan; UW Milwaukee, USA; LANL USA; Tokyo Tech, Japan;
IITB, India; IIA, India; LJMU, UK; TTU, USA; SDSU, USA and USyd, Australia.
ZTF acknowledges the generous support of the NSF under AST MSIP Grant No
1440341.
GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949.
Alert distribution service provided by DIRAC@UW (Patterson et al. 2019).
Alert database searches are done by AMPEL (Nordin et al. 2019) and Kowalski
(Duev et al. 2019). GROWTH India telescope is located at the Indian
Astronomical Observatory (Hanle), operated by the Indian Institute of
Astrophysics (IIA). GROWTH-India project is supported by SERB and
administered by IUSSTF, under grant number IUSSTF/PIRE
Program/GROWTH/2015-16 and IUCAA.








-- 
TomÃ¡s Ahumada (he/him)
Ph.D. Candidate
Department of Astronomy
University of Maryland, College Park
NASA <tomas.f.ahumdamena@nasa.gov> Goddard Space Flight Center, Code 661
B.Sc. Astronomy, Pontificia Universidad CatÃ³lica de Chile


GRB_name: GRB230512A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33800
SUBJECT: GRB 230512A: Nanshan/NEXT non-detection of GRB afterglow candidate
DATE:    23/05/14 23:03:22 GMT
FROM:    Dong Xu at NAOC/CAS <dxu@nao.cas.cn>

S.Q. Jiang, T.H. Lu, S.Y. Fu, X. Liu, Z.P. Zhu, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:

We observed the field of Fermi LAT localization (Maheso et al., GCN 33780) of short bright GRB 230512A (Fermi GBM team, GCN 33778; AstroSat, GCN 33779 and GRBAlpha, GCN 33795)
using the NEXT-0.6m optical telescope located at Nanshan, Xinjiang, China.

No optical source is detected in our stacked images at the XRT source 5 position. Preliminary photometric results are as follows:

T_mid-T0(day)   Filter   Upper_Limit(3-sigma)
    0.537              r          20.7
    1.543              r          21.8
    1.563              z          20.0

calibrated with the nearby PS1 stars and not corrected for Galactic extinction. The NEXT's first epoch image doesn't reveal the Kitab candidate (Belkin et al., GCN 33796), although it is deeper.

Some other XRT sources are also covered, and so far no credible optical afterglow candidate can be claimed.


GRB_name: GRB230513A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33801
SUBJECT: GRB 230513A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 705709044)
DATE:    23/05/15 01:06:55 GMT
FROM:    Tomas Ahumada at U. of Maryland <tahumada@astro.umd.edu>

Harsh Kumar (IITB), Vishwajeet Swain (IITB), Anirudh Salgundi (IITB), Aswin
Suresh (IITB), Tomas Ahumada (CIT), Viraj Karambelkar (CIT), Robert Stein
(CIT), Theophile du Laz (CIT), Igor Andreoni (UMD), Michael Coughlin (UMN),
Mansi Kasliwal (CIT), Simeon Reusch (DESY), Jannis Necker (DESY), Shreya
Anand (CIT), report on behalf of the ZTF collaboration:

We observed the localization region of the short GRB 230513A (trigger
705709044, GCN 33793) detected by the Gamma-Ray Burst Monitor (GBM) on the
Fermi satellite with the Palomar 48 inch telescope equipped with the 47
square degree Zwicky Transient Facility (ZTF) camera. We obtained a series
of g- and r-band images covering 410 square degrees beginning at
2023-05-14T03:42:31.003 (5 hours after the burst trigger time). This
corresponds to ~72% of the probability enclosed in the Earth-occultation
corrected GRB localization map. Each exposure was 300 seconds, reaching
g-band and r-band median depths of 22.2 mag and 22.0 mag respectively. The
images were processed in real-time through the ZTF reduction and image
subtraction pipelines at IPAC (Masci et al. 2019).

We queried the ZTF alert stream using Kowalski (Duev et al. 2019) through
Fritz (Coughlin et al. 2023) and AMPEL (Nordin et al. 2019). We required at
least 2 detections separated by at least 15 minutes to select against
moving objects. Furthermore, we cross-match our candidates with the Minor
Planet Center to flag known asteroids, reject stellar sources (Tachibana
and Miller 2018), and apply machine learning algorithms (Mahabal et al.
2019). We require that no spatially coincident ZTF alerts were issued
before the detection time of the GBM trigger. Close to 120 sources were
time and spatially coincident with the burst, most of them showing g-r ~ 0
mag and a slow evolution. We highlight the sources that show red colors
(i.e. g-r > 0.3 mag) in the table below, and we encourage follow up.


ZTF name , AT name , UT first alert , t-t0 , filter , mag , error
-----------------------------------------------------------------------------------------------
ZTF23aajklxl , AT 2023ilp , 2023-05-14 03:42:31.003 , 0.23 , r , 21.44 ,
0.14
ZTF23aajkqkc , AT 2023ilq , 2023-05-14 03:58:01.998 , 0.24 , r , 20.59 , 0.1
ZTF23aajkuyh , AT 2023ilr , 2023-05-14 04:18:53.001 , 0.25 , r , 21.56 ,
0.13
ZTF23aajlbzl , AT 2023ils , 2023-05-14 04:46:40.002 , 0.27 , g , 21.61 ,
0.15
ZTF23aajktjd , AT 2023ilt , 2023-05-14 04:13:34.003 , 0.25 , r , 21.77 ,
0.17


ZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC,
USA, WIS, Israel; OKC, Sweden; JSI/UMd, USA; U Washington, USA; DESY,
Germany; MOST, Taiwan; UW Milwaukee, USA; LANL USA; Tokyo Tech, Japan;
IITB, India; IIA, India; LJMU, UK; TTU, USA; SDSU, USA and USyd, Australia.
ZTF acknowledges the generous support of the NSF under AST MSIP Grant No
1440341.
GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949.
Alert distribution service provided by DIRAC@UW (Patterson et al. 2019).
Alert database searches are done by AMPEL (Nordin et al. 2019) and Kowalski
(Duev et al. 2019). GROWTH India telescope is located at the Indian
Astronomical Observatory (Hanle), operated by the Indian Institute of
Astrophysics (IIA). GROWTH-India project is supported by SERB and
administered by IUSSTF, under grant number IUSSTF/PIRE
Program/GROWTH/2015-16 and IUCAA.




-- 
TomÃ¡s Ahumada (he/him)
Ph.D. Candidate
Department of Astronomy
University of Maryland, College Park
NASA <tomas.f.ahumdamena@nasa.gov> Goddard Space Flight Center, Code 661
B.Sc. Astronomy, Pontificia Universidad CatÃ³lica de Chile


GRB_name: GRB230512A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33802
SUBJECT: IPN triangulation of GRB 230512A
DATE:    23/05/15 10:17:05 GMT
FROM:    Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>

D. Svinkin, D. Frederiks, A. Ridnaia, A. Lysenko, and
T. Cline on behalf of the Konus-Wind team,

A. Goldstein, M. S. Briggs, C. Wilson-Hodge,
and E. Burns on behalf of the Fermi GBM team,

and

S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu
on behalf of the Swift-BAT team, report:

The bright GRB 230512A
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 33778;
Roberts et al., GCN Circ. 33785;
AstroSat-CZTI detection: Navaneeth et al., GCN Circ. 33779;
Fermi-LAT detection: Maheso et al., GCN Circ. 33780;
GRBAlpha detection: Dafcikova et al., GCN Circ. 33795)
was detected by Fermi (GBM trigger 705565670; LAT), AstroSat (CZTI),
Konus-Wind, GRBAlpha, and Swift (BAT) at about 23265 s UT (06:27:45).
The burst was outside the coded field of view of the BAT.

We have triangulated it to a Konus-GBM annulus centered at
RA(2000)=252.326 deg (16h 49m 18s) Dec(2000)=-21.096 deg (-21d 05' 46"),
whose radius is 71.928 +/- 0.057 deg (3 sigma).

The LAT position reported by Maheso et al. (GCN Circ. 33780)
is consistent with the annulus. The annulus combined with
the LAT (90 % containment, statistical-only) error circle
gives the following error box:
---------------------------------
 RA(2000), deg   Dec(2000), deg
---------------------------------
  Center:
    295.4160    +38.4139
  Corners:
    295.6484    +38.1720
    295.7385    +38.2604
    295.1883    +38.6501
    295.0849    +38.5708
---------------------------------
The error box area is 242.2 sq. arcmin (a factor of ~4
smaller than that of the LAT error circle), and its maximum
dimension is 0.6 deg (the minimum one is 6.8 arcmin).
The Sun distance was 96 deg.

This box may be improved.

The Swift-XRT sources #2, 4, 8 (https://www.swift.ac.uk/xrt_products/TILED_GRB00111/) are inside the error box.

The OT candidate (Belkin et al., GCN Circ. 33796) is outside the error box.

A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB230512_T23265/IPN/

The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.


GRB_name: GRB230511D
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33803
SUBJECT: IPN triangulation of GRB 230511D (short)
DATE:    23/05/15 12:15:18 GMT
FROM:    Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>

D. Svinkin, D. Frederiks, A. Ridnaia, A. Lysenko,
on behalf of the IPN,

A. Goldstein, M. S. Briggs, C. Wilson-Hodge,
and E. Burns on behalf of the Fermi GBM team,

and

E. Bozzo and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,
report:

The short-duration GRB 230511D
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 33775)
was detected by Fermi (GBM trigger 705537623) and
INTEGRAL (SPI-ACS) at about 81618 s UT (22:40:18).

We have triangulated it to a GBM-SPI-ACS annulus centered at
RA(2000)=33.057 deg (02h 12m 14s) Dec(2000)=-40.890 deg (-40d 53' 25")
whose radius is 63.439 +/- 5.830 deg (3 sigma).

The annulus combined with the Fermi-GBM final position (GCN 33775;
glg_healpix_all_bn230511945_v00) gives 530 sq. deg (3 sigma) localization region.

A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB230511_T81618/IPN


GRB_name: GRB230516A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33804
SUBJECT: GRB 230516A: Fermi GBM Final Real-time Localization
DATE:    23/05/16 18:01:20 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 17:49:54 UT on 16 May 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230516A (trigger 705952199.76164 / 230516743).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 148.5, Dec = 29.6 (J2000 degrees, equivalent to J2000 09h 54m, 29d 36'), with a statistical uncertainty of 8.3 degrees.

The angle from the Fermi LAT boresight is 59.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230516743/quicklook/glg_skymap_all_bn230516743.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230516743/quicklook/glg_healpix_all_bn230516743.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230516743/quicklook/glg_lc_medres34_bn230516743.gif


GRB_name: GRB230510B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33806
SUBJECT: GRB 230510B: Fermi GBM detection
DATE:    23/05/16 21:23:02 GMT
FROM:    sumanbala2210@gmail.com

O.J. Roberts (USRA/NASA-MSFC), S. Bala (USRA), J. Wood (NASA-MSFC) and
C. Meegan (UAH) report on behalf of the Fermi GBM Team:

"At 21:21:34.01 UT on 10 May 2023, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 230510B (trigger 705446499 /230510890), which
was also detected by MAXI/GSC (M. Nakajima et al. 2023, GCN 33760),
CALET (P.S. Marrocchesi et al. 2023, GCN 33763), and CZTI/AstroSat 
(P.K. Navaneeth et al. 2023, GCN 33772). The Fermi GBM Final Real-time
 Localization (GCN 33759) is consistent with the MAXI/GSC position.

The angle from the Fermi LAT boresight at the GBM trigger time is 60 degrees.

The GBM light curve consists of two distinct peaks with multiple short
peaks in between with a duration (T90) of about 466 s (50-300 keV).
The time-averaged spectrum from T0-5.12 s to T0+650.81 s is
best fit by a Band function, with Epeak= 341 +/- 28 keV,
alpha = -1.32 +/- 0.02, and beta = -2.01 +/- 0.06.

The event fluence (10-1000 keV) in this time interval is
(1.28 +/- 0.01)E-04 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+194 s in the 10-1000 keV band
is 8.12 +/- 0.26 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"


GRB_name: GRB230517A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33807
SUBJECT: GRB 230517A: Fermi GBM Final Real-time Localization
DATE:    23/05/17 11:17:12 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 11:05:46 UT on 17 May 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230517A (trigger 706014351.299236 / 230517462).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 120.7, Dec = -49.1 (J2000 degrees, equivalent to J2000 08h 02m, -49d 06'), with a statistical uncertainty of 1.6 degrees.

The angle from the Fermi LAT boresight is 23.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230517462/quicklook/glg_skymap_all_bn230517462.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230517462/quicklook/glg_healpix_all_bn230517462.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230517462/quicklook/glg_lc_medres34_bn230517462.gif


GRB_name: GRB230512A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33808
SUBJECT: Improved IPN triangulation of GRB 230512A
DATE:    23/05/17 12:02:03 GMT
FROM:    Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>

A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin
on behalf of the MGNS/BepiColombo team,

J. Benkhoff on behalf of the BepiColombo team,

D. Svinkin, D. Frederiks, A. Ridnaia, A. Lysenko,
and T. Cline on behalf of the Konus-Wind team,

A. Goldstein, M. S. Briggs, C. Wilson-Hodge,
and E. Burns on behalf of the Fermi GBM team,

and

S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu
on behalf of the Swift-BAT team, report:

Using the BepiColombo (MGNS) data we have improved
the previous IPN box (Svinkin et al., GCN Circ. 33802),
The coordinates of the updated 3 sigma error box are:
 ---------------------------------------------
  RA(2000), deg                 Dec(2000), deg
 ---------------------------------------------
 Center:
  295.623 (19h 42m 30s) +38.267 (+38d 16' 00")
 Corners:
  295.645 (19h 42m 35s) +38.328 (+38d 19' 39")
  295.609 (19h 42m 26s) +38.353 (+38d 21' 10")
  295.601 (19h 42m 24s) +38.206 (+38d 12' 20")
  295.637 (19h 42m 33s) +38.180 (+38d 10' 49")
 ---------------------------------------------
The error box area is 15 sq. arcmin, and its maximum
dimension is 10 arcmin (the minimum one is 1.7 arcmin).
The Sun distance was 96 deg.

This box may be further improved.

None of the optical and X-ray transients found during the burst follow-up (GCNs 33784, 33789, 33796) are inside the box.

An updated triangulation map and HEALPix FITS files are posted at
http://www.ioffe.ru/LEA/GRBs/GRB230512_T23265/IPN/


GRB_name: GRB230517A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33809
SUBJECT: GRB 230517A: BALROG localization (Fermi Trigger 706014351 / GRB 230517462)
DATE:    23/05/17 12:51:43 GMT
FROM:    Jochen Greiner at MPI <jcg@mpe.mpg.de>

B. Biltzinger, F. Kunzweiler, J. Burgess & J. Greiner (all MPE Garching)
report:

The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
706014351 at 11:05:46 on 17 May 2023 were automatically fitted for spectrum
and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427;
Berlato et al. 2019, ApJ 873, 60).

The best-fit position (1 sigma statistical errors) is:
RA(2000.0) = 119.1+/-1.9 deg
Decl.(2000.0) = -48.6+/-0.7 deg
We estimate an additional systematic error of 1 deg.

Further details are available at:
https://grb.mpe.mpg.de/grb/GRB230517462/

The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB230517462/healpix

The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB230517462/json


GRB_name: GRB230510B
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33811
SUBJECT: GRB 230510B: GRBAlpha detection
DATE:    23/05/17 18:34:37 GMT
FROM:    Marianna DafÄÃ­kovÃ¡ at Masaryk University <500025@mail.muni.cz>

M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory), N. Werner (Masaryk U.), M. Ohno, H. Takahashi (Hiroshima U.), L. Meszaros, B. Csak (Konkoly Observatory), N. Husarikova, F. Munz , M. Topinka, M. Kolar, J.-P. Breuer, F. Hroch (Masaryk U.), T. Urbanec, M. Kasal,  A. Povalac (Brno U. of Technology), J. Hudec, J. Kapus, M. Frajt (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix s.r.o), M. Smelko, P. Hanak, P. Lipovsky (Technical U. of Kosice), G. Galgoczi (Wigner Research Center/Eotvos U.), Y. Uchida, H. Poon, H. Matake (Hiroshima U.), N. Uchida (ISAS/JAXA), T. Bozoki (Eotvos U.), G. Dalya (Eotvos U.), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), G. Friss (Eotvos U.), Y. Fukazawa, K. Hirose (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), K. Kapas (Eotvos U.), L. L. Kiss (Konkoly Observatory),  T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), J. Takatsy (Eotvos U.), K. Torigoe (Hiroshima U.), N. Kogiso, M. Yoneyama (Osaka Metropolitan U.), M. Moritaki (U. Tokyo), T. Kano (U. Michigan) -- the GRBAlpha collaboration.

The long-duration GRB 230510B (Fermi/GBM detection: GCN 33759; CALET/CGBM detection: GCN 33763; AstroSat detection: GCN 33772; Wind/Konus detection at 2023-05-10 21:21:35.995 UT; INTEGRAL/SPI-ACS detection at 2023-05-10 21:21:45 UT; GECAM-B trig. no. 178) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023; arXiv:2302.10048).

The detection was confirmed at the peak time 2023-05-10 21:20:55 UTC. The T90 duration measured by GRBAlpha is 198 s and the overall significance during T90 reaches 14 sigma in the 80-400 keV band.

The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB230510B_GCN.pdf

All GRBAlpha detections are listed at: https://monoceros.physics.muni.cz/hea/GRBAlpha/ 
GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume. 


GRB_name: GRB230513A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33812
SUBJECT: GRB 230513A: Zwicky Transient Facility continuous observations of a Fermi Short GRB (Trigger 705709044)
DATE:    23/05/18 04:32:06 GMT
FROM:    Tomas Ahumada at U. of Maryland <tahumada@astro.umd.edu>

Tomas Ahumada (CIT), Viraj Karambelkar (CIT), Robert Stein (CIT), Harsh
Kumar (IITB), Vishwajeet Swain (IITB), Anirudh Salgundi (IITB), Aswin
Suresh (IITB),  Theophile du Laz (CIT), Igor Andreoni (UMD), Michael
Coughlin (UMN), Mansi Kasliwal (CIT), Varun Bhalerao (IITB), Simeon Reusch
(DESY), Jannis Necker (DESY), Shreya Anand (CIT), report on behalf of the
ZTF collaboration:

We re-observed the localization region of the short GRB 230513A (trigger
705709044, GCN 33793) detected by the Gamma-Ray Burst Monitor (GBM) on the
Fermi satellite with the Palomar 48 inch telescope equipped with the 47
square degree Zwicky Transient Facility (ZTF) camera. We obtained a series
of g- and r-band images beginning at 29 and 77 hours after the burst
trigger time. For the first epoch of observations we covered 619.3 square
degrees corresponding to ~82% of the probability region and reaching a
median depth of 21.85 mag in the 300 sec r-band exposures, 22.36 mag in the
450 sec r-band exposures, and 21.82 mag in the 300 sec g-band exposures.
For the second epoch ZTF covered 671.9 square degrees, corresponding to
~85% of the region, and reaching a median depth of 21.71 mag in 300 sec
r-band exposures. The images were processed in real-time through the ZTF
reduction and image subtraction pipelines at IPAC (Masci et al. 2019).

We queried the ZTF alert stream using Kowalski (Duev et al. 2019) through
Fritz (Coughlin et al. 2023) and AMPEL (Nordin et al. 2019). We required at
least 2 detections separated by at least 15 minutes to select against
moving objects. Furthermore, we cross-match our candidates with the Minor
Planet Center to flag known asteroids, reject stellar sources (Tachibana
and Miller 2018), and apply machine learning algorithms (Mahabal et al.
2019). We require that no spatially coincident ZTF alerts were issued
before the detection time of the GBM trigger. Close to 200 sources were
time and spatially coincident with the burst. No source showed a
photometric evolution  consistent with a GRB afterglow, including the ones
circulated on GCN 33801.


ZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC,
USA, WIS, Israel; OKC, Sweden; JSI/UMd, USA; U Washington, USA; DESY,
Germany; MOST, Taiwan; UW Milwaukee, USA; LANL USA; Tokyo Tech, Japan;
IITB, India; IIA, India; LJMU, UK; TTU, USA; SDSU, USA and USyd, Australia.
ZTF acknowledges the generous support of the NSF under AST MSIP Grant No
1440341.
GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949.
Alert distribution service provided by DIRAC@UW (Patterson et al. 2019).
Alert database searches are done by AMPEL (Nordin et al. 2019) and Kowalski
(Duev et al. 2019). GROWTH India telescope is located at the Indian
Astronomical Observatory (Hanle), operated by the Indian Institute of
Astrophysics (IIA). GROWTH-India project is supported by SERB and
administered by IUSSTF, under grant number IUSSTF/PIRE
Program/GROWTH/2015-16 and IUCAA.




-- 
TomÃ¡s Ahumada (he/him)
Ph.D. Candidate
Department of Astronomy
University of Maryland, College Park
NASA <tomas.f.ahumdamena@nasa.gov> Goddard Space Flight Center, Code 661
B.Sc. Astronomy, Pontificia Universidad CatÃ³lica de Chile


GRB_name: GRB230518A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33822
SUBJECT: GRB 230518A: Fermi GBM Final Real-time Localization
DATE:    23/05/18 22:59:56 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely SHORT GRB

At 22:49:27 UT on 18 May 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230518A (trigger 706142972.60896 / 230518951).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 256.4, Dec = -49.6 (J2000 degrees, equivalent to J2000 17h 05m, -49d 36'), with a statistical uncertainty of 19.0 degrees.

The angle from the Fermi LAT boresight is 23.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230518951/quicklook/glg_skymap_all_bn230518951.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230518951/quicklook/glg_healpix_all_bn230518951.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230518951/quicklook/glg_lc_medres34_bn230518951.gif


GRB_name: GRB230518A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33825
SUBJECT: GRB 230518A: Swift/BAT-GUANO detection
DATE:    23/05/19 11:34:53 GMT
FROM:    Aaron Tohuvavohu at University of Toronto <aaron.tohu@gmail.com>

Samuele Ronchini (PSU), Gayathri Raman (PSU), James DeLaunay (UAlabama), Aaron Tohuvavohu (U Toronto), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report:

Swift/BAT did not localize GRB 230518A onboard (T0: 2023-05-18T22:49:27.61 UTC, Fermi/GBM GCN 33822). 

The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). 

Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground.

The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), detects the burst with a sqrt(TS) of 11 in a 0.128 s analysis time bin.
The burst duration is ~0.256 seconds.

NITRATES results, independently, are ambiguous with respect to whether this burst originates from in or outside the BAT coded FOV, with a borderline DeltaLLHOut of 6.5.
The majority of the Fermi/GBM localization lies outside the coded FOV.

See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descriptions and interpretation of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut.

GUANO is a fully autonomous, extremely low latency, spacecraft
commanding pipeline designed for targeted recovery of BAT event mode
data around the times of compelling astrophysical events to enable
more sensitive GRB searches.

A live reporting of Swift/BAT event data recovered by GUANO can be
found at: https://www.swift.psu.edu/guano/


GRB_name: GRB230518A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33828
SUBJECT: GRB 230518A: Fermi GBM Observation
DATE:    23/05/19 17:07:45 GMT
FROM:    sumanbala2210@gmail.com

S. Bala (USRA), C. Fletcher (USRA) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 22:49:27.61 UT on 18 May 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230518A (trigger 706142972/230518951).
which was also detected by Swift/BAT-GUANO (S. Ronchini et al. 2023, GCN
33825).
The Fermi GBM Final Real-time Localization was reported in GCN 33822.

The angle from the Fermi LAT boresight is 23 degrees.

The GBM light curve consists of one short peak with a duration (T90)
of about 0.9 s (50-300 keV). The time-averaged spectrum
from T0-0.7 to T0+0.2 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is 0.6 +/- 0.7 and the cutoff energy,
parameterized as Epeak, is 503 +/- 138 keV.

The event fluence (10-1000 keV) in this time interval is
(5.5 +/- 0.9)E-07 erg/cm^2. The 64-ms peak photon flux measured
starting from T0+0.0 s in the 10-1000 keV band is 4 +/- 1 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support
Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"


GRB_name: GRB230520A
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33831
SUBJECT:   GRB 230520A: MAXI/GSC detection
DATE:    23/05/20 05:51:53 GMT
FROM:    Motoko Serino at Aoyama Gakuin U. <serino@phys.aoyama.ac.jp>

Y. Umeki (Miyazaki U.), M. Serino (AGU), Y. Kawakubo (LSU),
H. Negoro, M. Nakajima, K. Kobayashi, M. Tanaka, Y. Soejima, Y. Kudo (Nihon U.),
T. Mihara, T. Kawamuro, S. Yamada, T. Tamagawa, N. Kawai, M. Matsuoka (RIKEN),
T. Sakamoto, S. Sugita, H. Hiramatsu, H. Nishikawa, A. Yoshida (AGU),
Y. Tsuboi, S. Urabe, S. Nawa, N. Nemoto (Chuo U.),
M. Shidatsu (Ehime U.),
I. Takahashi, M. Niwano, S. Sato, N. Higuchi, Y. Yatsu (Tokyo Tech),
S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, S. Ogawa, T. Kurihara (JAXA),
Y. Ueda, K. Setoguchi, T. Yoshitake, Y. Nakatani (Kyoto U.),
M. Yamauchi, Y. Hagiwara, Y. Otsuki (Miyazaki U.),
K. Yamaoka (Nagoya U.),
M. Sugizaki (NAOC),
W. Iwakiri (Chiba U.) 
report on behalf of the MAXI team:

The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray 
transient source at 05:03:24 UT on 20 May 2023.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (142.422 deg, 1.524 deg) = (09 29 41, +01 31 26) (J2000)
with a statistical 90% C.L. elliptical error region
with long and short radii of 0.04 deg and 0.03 deg, respectively.
The roll angle of long axis from the north direction is 90.0 deg counterclockwise.
Without assumptions on the source constancy, we obtain a rectangular error
box for the transient source with the following corners:
(142.239, 1.362) deg = (09 28 57, +01 21 43) (J2000)
(142.281, 1.327) deg = (09 29 07, +01 19 37) (J2000)
(142.576, 1.677) deg = (09 30 18, +01 40 37) (J2000)
(142.535, 1.712) deg = (09 30 08, +01 42 43) (J2000) 
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 1405 +- 69 mCrab
(4.0-10.0keV, 1 sigma error).
There was no significant excess flux in the previous transit at 03:30 UT
with an upper limit of 20 mCrab.


GRB_name: GRB230520B
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33836
SUBJECT: GRB 230520B: Fermi GBM Final Real-time Localization
DATE:    23/05/20 23:22:06 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 23:11:39 UT on 20 May 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230520B (trigger 706317104.139708 / 230520966).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 31.7, Dec = -62.1 (J2000 degrees, equivalent to J2000 02h 06m, -62d 06'), with a statistical uncertainty of 1.0 degrees.

The angle from the Fermi LAT boresight is 152.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230520966/quicklook/glg_skymap_all_bn230520966.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230520966/quicklook/glg_healpix_all_bn230520966.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230520966/quicklook/glg_lc_medres34_bn230520966.gif


GRB_name: GRB230520B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33837
SUBJECT: GRB 230520B is not a GRB
DATE:    23/05/21 00:41:11 GMT
FROM:    Suraj Poolakkil at UAH <sp0076@uah.edu>

S. Poolakkil (UAH) reports on behalf of the Fermi Gamma-ray Burst Monitor
Team:

"The Fermi Gamma-ray Burst Monitor (GBM) trigger 706317104/230520966 at 23:11:39.14 UT
on 20 May 2023, tentatively classified as GRB 230520B (GCN 33836), is
in fact not due to a GRB. This trigger is likely due to Local Particles."


GRB_name: GRB230521A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33839
SUBJECT: GRB 230521A: Fermi GBM Final Real-time Localization
DATE:    23/05/21 05:13:46 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely SHORT GRB

At 05:03:23 UT on 21 May 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230521A (trigger 706338208.733194 / 230521211).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 37.0, Dec = 7.6 (J2000 degrees, equivalent to J2000 02h 28m, 7d 35'), with a statistical uncertainty of 7.8 degrees.

The angle from the Fermi LAT boresight is 54.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230521211/quicklook/glg_skymap_all_bn230521211.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230521211/quicklook/glg_healpix_all_bn230521211.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230521211/quicklook/glg_lc_medres34_bn230521211.gif


GRB_name: GRB230520A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33840
SUBJECT: GRB 230520A: CALET Gamma-Ray Burst Monitor detection
DATE:    23/05/21 06:10:46 GMT
FROM:    Yuta Kawakubo at Louisiana State University <kawakubo1@lsu.edu>

T. Sakamoto, A. Yoshida, S. Sugita (AGU), Y. Kawakubo (LSU), 
K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), Y. Asaoka (ICRR),
S. Torii, Y. Akaike, K. Kobayashi (Waseda U),
Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC),
M. L. Cherry (LSU), S. Ricciarini (U of Florence),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

The long GRB 230520A (MAXI/GSC detection: Umeki et al., 
GCN Circ. 33831) was detected in the ground analysis of the CALET 
Gamma-ray Burst Monitor (CGBM) data around 05:03:24 UTC on 20 
May 2023 (referenced to GCN Circ 33831).
The burst signal was seen by all CGBM detectors.

The burst light curve shows a multi-peaked structure that starts
at T-82.9 sec, peaks at T+9.0 sec, and ends at T+34.9 sec.
The T90 and T50 durations measured by the SGM data are 98.1 +/- 4.3 sec
and 67.5 +/- 3.7 sec (40-1000 keV), respectively.

The ground-processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1368594148/

The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.


GRB_name: GRB230518A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33843
SUBJECT: IPN triangulation of GRB 230518A (short)
DATE:    23/05/21 13:50:51 GMT
FROM:    Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>

D. Svinkin, D. Frederiks, A. Ridnaia, A. Lysenko,
on behalf of the IPN,

A. Goldstein, M. S. Briggs, C. Wilson-Hodge,
and E. Burns on behalf of the Fermi GBM team,

E. Bozzo and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,

and

S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu
on behalf of the Swift-BAT team, report:


The short-duration GRB 230518A
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 33822;
Swift-BAT/GUANO detection: Ronchini, GCN Circ. 33825)
has been detected by Fermi (GBM trigger 706142972), Swift (BAT),
and INTEGRAL (SPI-ACS), so far, at about 82168 s UT (22:49:28).
The burst was outside the coded field of view of the BAT.

We have triangulated it to a GBM-SPI-ACS annulus centered at
RA(2000)=19.521 deg (01h 18m 05s) Dec(2000)=-66.594 deg (-66d 35' 40")
whose radius is 88.662 +/- 2.786 deg (3 sigma).

The annulus combined with the Fermi-GBM final position (GCN 33822;
glg_healpix_all_bn230518951_v00) gives 480 sq. deg (3 sigma) localization region.

The localization is inconsistent with the localization of the NSBH merger event candidate S230518h (LVK Collaborations, GCN Circ. 33813, 33816).

A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB230518_T82167/IPN/


GRB_name: GRB230521A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33846
SUBJECT: Fermi Gamma-ray Burst Monitor trigger 706338208/230521211 is not a GRB
DATE:    23/05/22 00:19:06 GMT
FROM:    Stephen Lesage at Fermi-GBM Team <sjl0014@uah.edu>

S. Lesage (UAH) reports on behalf of the Fermi Gamma-ray Burst Monitor Team:

"The Fermi Gamma-ray Burst Monitor (GBM) trigger 706338208/230521211 at
05:03:23 UT
on 21 May 2023, tentatively classified as GRB 230521A (GCN 33839), is in
fact not due
to a GRB. This trigger is likely due to Uncertain."


GRB_name: GRB230518B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33847
SUBJECT: GRB 230518B: VZLUSAT-2 detection
DATE:    23/05/22 03:38:03 GMT
FROM:    Marianna DafÄÃ­kovÃ¡ at Masaryk University <500025@mail.muni.cz>

M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory),  N. Werner  (Masaryk U.), M. Ohno (Hiroshima U.),  L. Meszaros, B. Csak (Konkoly Observatory), H. Takahashi (Hiroshima U.), F. Munz , M. Topinka, F. Hroch, N. Husarikova, J.-P. Breuer (Masaryk U.), J. Hudec, J. Kapus, M. Frajt, M. Rezenov (Spacemanic s.r.o), R. Laszlo (Needronix), G. Galgoczi (Wigner Research Center/Eotvos U.), N. Uchida (ISAS/JAXA), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), Y. Fukazawa, K. Hirose, H. Matake (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), L. L. Kiss (Konkoly Observatory),  T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), K. Torigoe (Hiroshima U.), P. Svoboda, V. Daniel, J. Dudas, M. Junas, J. Gromes (VZLU), I. Vertat (FEL ZCU)  -- the VZLUSAT-2/GRB payload collaboration.

The long duration GRB 230518B (Fermi/GBM detection: trigger no. 706068974 initially classified as a GRB; INTEGRAL/SPI-ACS peak detection at 2023-05-18 02:18:15 UT) was detected by the GRB detector on board of the VZLUSAT-2 3U CubeSat (https://www.vzlusat2.cz/en/).

The data acquisition was performed by the GRB detector unit no. 1. The detection was confirmed at the peak time 2023-05-18 02:18:17 UTC. The T90 duration measured by VZLUSAT-2 is 138 s and the significance during T90 reaches 33 sigma.

The light curve obtained by VZLUSAT-2 is available here:
https://vzlusat2.konkoly.hu/static/share/GRB230518B_GCN_VZLUSAT2.pdf

The event was re-evaluated by the Fermi/GBM team (J. Wood, GCN Circ. 33821) to be likely due to local particles. The Fermi satellite was at the GBM trigger time 2023-05-18 02:16:09.41 UT at longitude = 24.33 deg, latitude = -24.43 deg. The VZLUSAT-2 satellite was at that time at longitude = 109.9 deg, latitude = -28.4 deg. Since this event was detected by three satellites at different locations, we believe this event is of astrophysical origin and possibly a long-duration GRB.

All VZLUSAT-2 detections are listed at: https://monoceros.physics.muni.cz/hea/VZLUSAT-2/
The GRB detectors on VZLUSAT-2 are a demonstration payload for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). Two GRB modules of VZLUSAT-2 are placed in a perpendicular manner and each consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~30 keV to ~1000 keV. VZLUSAT-2 was launched on 2022 January 13 from Cape Canaveral.


GRB_name: GRB230523A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33856
SUBJECT: GRB 230523A: Fermi GBM Final Real-time Localization
DATE:    23/05/23 11:33:48 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 11:23:09 UT on 23 May 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230523A (trigger 706533794.188064 / 230523474).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 129.4, Dec = 29.0 (J2000 degrees, equivalent to J2000 08h 37m, 29d 00'), with a statistical uncertainty of 3.7 degrees.

The angle from the Fermi LAT boresight is 43.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230523474/quicklook/glg_skymap_all_bn230523474.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230523474/quicklook/glg_healpix_all_bn230523474.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230523474/quicklook/glg_lc_medres34_bn230523474.gif


GRB_name: GRB230523A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33859
SUBJECT: GRB 230523A: Swift/BAT-GUANO detection of a short hard burst
DATE:    23/05/23 22:58:55 GMT
FROM:    Aaron Tohuvavohu at University of Toronto <aaron.tohu@gmail.com>

Gayathri Raman (PSU), Samuele Ronchini (PSU), James DeLaunay (UAlabama), Aaron Tohuvavohu (U Toronto), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report:

Swift/BAT did not localize GRB 230523A onboard (T0: 2023-05-23T15:23:52.68 UTC, INTEGRAL/SPI-ACS #10268). 

The INTEGRAL notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). 

Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 90 seconds of BAT event-mode data from [-45,+45] seconds around the time of the burst. All the requested event mode data was delivered to the ground.

The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), detects the burst with a sqrt(TS) of 12.4 in a 1.024 s analysis time bin.
The burst duration is ~2 seconds.

NITRATES results, independently, are ambiguous with respect to whether this burst originates from in or outside the BAT coded FOV, with a borderline DeltaLLHOut of 8.33.

See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descriptions and interpretation of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut.

GUANO is a fully autonomous, extremely low latency, spacecraft
commanding pipeline designed for targeted recovery of BAT event mode
data around the times of compelling astrophysical events to enable
more sensitive GRB searches.

A live reporting of Swift/BAT event data recovered by GUANO can be
found at: https://www.swift.psu.edu/guano/


GRB_name: GRB230523B
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33860
SUBJECT: GRB 230523B: Name correction from GCN Circular 33859
DATE:    23/05/23 23:04:04 GMT
FROM:    Aaron Tohuvavohu at University of Toronto <aaron.tohu@gmail.com>

GCN Circular 33859 incorrectly named "Swift/BAT-GUANO detection of a short hard burst" for a GRB at T0: 2023-05-23T15:23:52.68 UTC as GRB 230523A.
This burst should instead be named GRB 230523B. 
I apologize for the mistake.


GRB_name: GRB230524A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33864
SUBJECT: GRB 230524A: Fermi GBM Final Real-time Localization
DATE:    23/05/24 06:16:55 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 06:06:35 UT on 24 May 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230524A (trigger 706601200.806822 / 230524255).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 177.5, Dec = 16.3 (J2000 degrees, equivalent to J2000 11h 50m, 16d 18'), with a statistical uncertainty of 3.2 degrees.

The angle from the Fermi LAT boresight is 93.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230524255/quicklook/glg_skymap_all_bn230524255.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230524255/quicklook/glg_healpix_all_bn230524255.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230524255/quicklook/glg_lc_medres34_bn230524255.gif


GRB_name: GRB230524A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33867
SUBJECT: GRB 230524A: AGILE detection
DATE:    23/05/24 11:35:12 GMT
FROM:    Gabriele Panebianco <gabriele.panebianco@inaf.it>

 G. Panebianco (Univ. Bologna - INAF/OAS Bologna), A. Ursi (ASI and INAF/IAPS), F. Verrecchia, C. Pittori (SSDC, and INAF/OAR), F. Longo (Univ. Trieste and INFN Trieste), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), C. Casentini, A. Argan, M. Cardillo, Y. Evangelista, L. Foffano,  G. Piano (INAF/IAPS), A. Addis, L. Baroncelli, A. Bulgarelli, A. Di Piano, V. Fioretti,  N. Parmiggiani (INAF/OAS-Bologna), F. Lucarelli (SSDC, and INAF/OAR), M. Marisaldi (INAF/OAS-Bologna, and Bergen University), M. Pilia, A. Trois (INAF/OA-Cagliari), I. Donnarumma, E. Menegoni (ASI), A. Giuliani (INAF/IASF-Mi), and P. Tempesta (TeleSpazio), report on behalf of the AGILE Team:

The AGILE satellite detected the GRB 230524A at T0 =  2023-05-24 06:06:35 s
(UTC), reported by Fermi GBM (GCN #33864).
The burst is clearly visible in the AGILE scientific ratemeters of the
MiniCALorimeter (MCAL; 0.4-100 MeV), and AntiCoincidence (AC; 50-200 keV)
detectors.
The event lasted about 12 s and it released a total number
of 8723 counts in the MCAL detector (above a background rate of 595 Hz)
and 43686 counts in the AC-Top detector (above a background rate of 3171 Hz).
The AGILE ratemeters light curves can be found at http://www.agilescienceapp.it/notices/GRB230524A_AGILE_RM_D.png .

Additional analysis of AGILE data is in progress. Automatic MCAL GRB alert Notices can be found at: https://gcn.gsfc.nasa.gov/agile_mcal.html


GRB_name: GRB230524A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33868
SUBJECT: GRB 230524A: AstroSat CZTI detection
DATE:    23/05/24 13:31:35 GMT
FROM:    Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>

P K. Navaneeth (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long GRB 230524A which was also detected by Fermi (Fermi GBM Team, GCN Circ. 33864), and AGILE (Panebianco et al., GCN Circ. 33867).

The source was detected in the 20-200 keV energy range. The light curve peaks at 2023-05-24 06:06:40.50 UTC. The measured peak count rate associated with the burst is 97 (+37, -13) counts/s above the background in the combined data of three quadrants (out of four), with a total of 617 (+249, -270) counts. The local mean background count rate was 324 (+2, -2) counts/s. Using cumulative rates, we measure a T90 of 16 (+6, -10) s.

The source was clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2023-05-24 06:06:40.50 UTC. The measured peak count rate associated with the burst is 448 (+71, -56) counts/s above the background in the combined data of all quadrants, with a total of 5102 (+531, -606) counts. The local mean background count rate was 1398 (+5, -5) counts/s. We measure a T90 of 22 (+10, -4) s from the cumulative Veto light curve.

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb


GRB_name: GRB230524B
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33869
SUBJECT: GRB 230524B: AstroSat CZTI detection
DATE:    23/05/24 13:36:46 GMT
FROM:    Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>



P K. Navaneeth (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a probable long GRB 230524B which was also detected by Fermi-GBM (Trigger Number 706599831).

The source was detected in the 20-200 keV energy range. The light curve peaks at 2023-05-24 05:43:58.50 UTC. The measured peak count rate associated with the burst is 108 (+47, -6) counts/s above the background in the combined data of all quadrants, with a total of 1060 (+469, -248) counts. The local mean background count rate was 409 (+2, -3) counts/s. Using cumulative rates, we measure a T90 of 21 (+12, -8) s.

The source was also detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range.

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb


GRB_name: GRB230524A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33874
SUBJECT: GRB 230524A: Fermi GBM Observation
DATE:    23/05/25 10:00:14 GMT
FROM:    Andreas von Kienlin at MPE <azk@mpe.mpg.de>

A. von Kienlin (MPE) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 06:06:35 UT on 24 May 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230524A (trigger 706601200/230524255), 
which was also detected by AGILE (Panebianco et al. 2023, GCN 33867) 
and AstroSAT/CZTI (Navaneeth et al. 2022, GCN 33868).
The Fermi GBM Final Real-time Localization was reported in GCN 33864.

The GBM light curve  consists of a single emission with a duration (T90) 
of about 35 s (50-300 keV). The time-averaged spectrum
from T0-2.0 to T0+36.9 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -0.99 +/- 0.04 and the cutoff energy,
parameterized as Epeak, is 1632 +/- 415 keV.

The event fluence (10-1000 keV) in this time interval is
(1.58 +/- 0.05)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-2 s in the 10-1000 keV band is 2.7 +/- 0.2 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support
Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"


GRB_name: GRB230523B
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33875
SUBJECT: GRB 230523B: GRBAlpha detection
DATE:    23/05/25 10:57:50 GMT
FROM:    Marianna DafÄÃ­kovÃ¡ at Masaryk University <500025@mail.muni.cz>

M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory), N. Werner (Masaryk U.), M. Ohno, H. Takahashi (Hiroshima U.), L. Meszaros, B. Csak (Konkoly Observatory), N. Husarikova, F. Munz , M. Topinka, M. Kolar, J.-P. Breuer, F. Hroch (Masaryk U.), T. Urbanec, M. Kasal,  A. Povalac (Brno U. of Technology), J. Hudec, J. Kapus, M. Frajt (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix s.r.o), M. Smelko, P. Hanak, P. Lipovsky (Technical U. of Kosice), G. Galgoczi (Wigner Research Center/Eotvos U.), Y. Uchida, H. Poon, H. Matake (Hiroshima U.), N. Uchida (ISAS/JAXA), T. Bozoki (Eotvos U.), G. Dalya (Eotvos U.), yyT. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), G. Friss (Eotvos U.), Y. Fukazawa, K. Hirose (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), K. Kapas (Eotvos U.), L. L. Kiss (Konkoly Observatory),  T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), J. Takatsy (Eotvos U.), K. Torigoe (Hiroshima U.), N. Kogiso, M. Yoneyama (Osaka Metropolitan U.), M. Moritaki (U. Tokyo), T. Kano (U. Michigan) -- the GRBAlpha collaboration.

The short-duration GRB 230523B (Swift/BAT-GUANO detection: GCN 33859; INTEGRAL/SPI-ACS trigger no. 10268; Konus/Wind detection at 2023-05-23 15:23:51.501 UT) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023; arXiv:2302.10048).

The detection was confirmed at the peak time 2023-05-23 15:23:53 UTC. The light curve observed by GRBAlpha shows a spike within one 1 s bin where the SNR reaches 5 sigma.

The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB230523B_GCN.pdf

All GRBAlpha detections are listed at: https://monoceros.physics.muni.cz/hea/GRBAlpha/ 
GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume. 


GRB_name: GRB230525A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33877
SUBJECT: GRB 230525A: Fermi GBM Final Localization
DATE:    23/05/25 14:54:44 GMT
FROM:    Cori Fletcher at USRA <cfletcher@usra.edu>

The Fermi GBM team reports the detection of a likely SHORT GRB

"At 10:46:08 UT on 25 May 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230525A (trigger 706704373/230525449).

The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 45.27, Dec = 69.35 (J2000 degrees, equivalent to J2000 3h 1m, +69d 20'),
with a statistical uncertainty of 6.75 degrees.

The angle from the Fermi LAT boresight is 19 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230525449/quicklook/glg_skymap_all_bn230525449.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230525449/quicklook/glg_healpix_all_bn230525449.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230525449/quicklook/glg_lc_medres34_bn230525449.gif"


GRB_name: GRB230525A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33879
SUBJECT: GRB 230525A: Fermi GBM Detection
DATE:    23/05/25 17:10:06 GMT
FROM:    sumanbala2210@gmail.com

S. Bala (USRA), C. Fletcher (USRA), O.J. Roberts (NASA/MSFC) and C. Meegan (UAH)
 report on behalf of the Fermi Gamma-ray Burst Monitor Team:

"At 10:46:08.33 UT on 25 May 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230525A (trigger 706704373/230525449).
The Fermi GBM Final Real-time Localization was reported in GCN 33877.

The angle from the Fermi LAT boresight is 19 degrees.

The GBM light curve consists of single peak with a duration (T90)
of 0.12 s (50-300 keV). The time-averaged spectrum
from T0-0.06 to T0+0.06 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -0.80 +/- 0.09 and the cutoff energy,
parameterized as Epeak, is 789 +/- 148 keV.

The event fluence (10-1000 keV) in this time interval is
(8.6 +/- 0.4)E-07 erg/cm^2. The 64-ms peak photon flux measured
starting from T0-0.064 s in the 10-1000 keV band is 25 +/- 1 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"


GRB_name: GRB230510A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33880
SUBJECT: GRB 230510A: Swift-BAT refined analysis
DATE:    23/05/26 13:27:36 GMT
FROM:    Takanori Sakamoto at AGU <tsakamoto@phys.aoyama.ac.jp>

S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC), R. A. J. Eyles-Ferris (U Leicester),
H. A. Krimm (NSF), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU), M. Stamatikos (OSU)
(i.e. the Swift-BAT team):
 Using the data set from T-240 to T+349 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 230510A (trigger #1167973)
(Eyles-Ferris, et al., GCN Circ. 33752).  The BAT ground-calculated position is
RA, Dec = 318.138, 34.430 deg which is
   RA(J2000)  =  21h 12m 33.2s
   Dec(J2000) = +34d 25' 49.8"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
 The mask-weighted light curve shows a precursor starting at T-150 s with
a duration of ~20 s.  The bright main episode starts at T-10 s, peaks at
T+15 s, and ends at T+60 s.  T90 (15-350 keV) is 178.4 +- 6.9 sec
(estimated error including systematics).
 The time-averaged spectrum from T-145.6 to T+56.8 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.60 +- 0.09.  The fluence in the 15-150 keV band is 1.0 +- 0.1 x 10^-5 erg/cm2.
The 1-sec peak photon flux measured from T+13.39 sec in the 15-150 keV band
is 5.9 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.
 The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1167973/BA/


GRB_name: GRB230529A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33887
SUBJECT: GRB 230529A: Fermi GBM Final Real-time Localization
DATE:    23/05/29 08:05:21 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 07:54:45 UT on 29 May 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230529A (trigger 707039690.316368 / 230529330).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 346.8, Dec = -50.0 (J2000 degrees, equivalent to J2000 23h 07m, -50d 00'), with a statistical uncertainty of 12.7 degrees.

The angle from the Fermi LAT boresight is 42.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230529330/quicklook/glg_skymap_all_bn230529330.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230529330/quicklook/glg_healpix_all_bn230529330.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230529330/quicklook/glg_lc_medres34_bn230529330.gif


GRB_name: GRB230525A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33901
SUBJECT: GRB 230525A: CALET Gamma-Ray Burst Monitor detection
DATE:    23/05/31 06:20:08 GMT
FROM:    Yuta Kawakubo at Louisiana State University <kawakubo1@lsu.edu>

Y. Kawakubo (LSU), A. Yoshida, T. Sakamoto, S. Sugita (AGU), 
K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), Y. Asaoka (ICRR),
S. Torii, Y. Akaike, K. Kobayashi (Waseda U),
Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC),
M. L. Cherry (LSU), S. Ricciarini (U of Florence),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

The short GRB 230525A (Fermi-GBM Final Localization: The 
Fermi GBM team, GCN Circ. 33877; Fermi-GBM detection: The Fermi 
GBM team, GCN Circ. 33879) was detected in the ground analysis of 
the CALET Gamma-ray Burst Monitor (CGBM) data around 
10:46:08.33 UTC on 25 May 2023 (referenced to GCN Circ 33879).
The burst signal was seen by all CGBM detectors.

The burst light curve shows a short pulse around the reference time. 
We are not able to obtain the duration because no event data is available 
for ground-detected events.

The ground-processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1369046781/

The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.


GRB_name: GRB230522A
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33905
SUBJECT: GRB 230522A: GRBAlpha and VZLUSAT-2 joint detection
DATE:    23/06/02 16:58:50 GMT
FROM:    Marianna DafÄÃ­kovÃ¡ at Masaryk University <500025@mail.muni.cz>

M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory),  N. Werner  (Masaryk U.), M. Ohno, H. Takahashi (Hiroshima U.), L. Meszaros, B. Csak (Konkoly Observatory), N. Husarikova, F. Munz, M. Topinka, M. Kolar, J.-P. Breuer, F. Hroch (Masaryk U.), J. Hudec, J. Kapus, M. Frajt, M. Rezenov (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix s.r.o), G. Galgoczi (Wigner Research Center/Eotvos U.), N. Uchida (ISAS/JAXA), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), Y. Fukazawa, K. Hirose, H. Poon, H. Matake (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), L. L. Kiss (Konkoly Observatory),  T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (U. Tokyo), K. Torigoe, Y. Uchida (Hiroshima U.), P. Svoboda, V. Daniel, J. Dudas, M. Junas, J. Gromes (VZLU), I. Vertat (FEL ZCU), T. Urbanec, M. Kasal, A. Povalac (Brno U. of Technology), M. Smelko, P. Hanak, P. Lipovsky (Technical U. of Kosice), T. Bozoki, G. Dalya, G. Friss, K. Kapas, J. Takatsy (Eotvos U.), N. Kogiso, M. Yoneyama (Osaka Metropolitan U.), M. Moritaki (U. Tokyo), T. Kano (U. Michigan) -- the GRBAlpha and VZLUSAT-2/GRB payload collaborations

We report a joint detection of a likely long-duration GRB 230522A by the GRBAlpha 1U CubeSat (Pal et al. 2023; arXiv:2302.10048) and the GRB detectors on board of VZLUSAT-2 3U CubeSat (https://www.vzlusat2.cz/en/). The event was triggered by Konus/Wind at 2023-05-22 03:34:41.414 UT and also observed by INTEGRAL/SPI-ACS at 2023-05-22 03:34:45 UT. The Sun was occulted by the Earth for both CubeSats, therefore, it is unlikely to be a solar flare.

The GRBAlpha detection was confirmed at the peak time 2023-05-22 03:34:45 UTC. The T90 duration is 11 s and the significance during T90 reaches 47 sigma.

The light curve obtained by GRBAlpha is available here:
https://grbalpha.konkoly.hu/static/share/GRB230522A_GCN.pdf

The VZLUSAT-2 detection was confirmed at the peak time 2023-05-22 03:34:43 UTC. The data acquisition was performed by the GRB detector units no. 0 and no. 1. The T90 duration is 10 s (12 s) and the significance during T90 reaches 30 sigma (9 sigma) for detector unit no. 0 (no. 1).

The light curves obtained by VZLUSAT-2 are available here:
https://vzlusat2.konkoly.hu/static/share/GRB230522A_GCN_VZLUSAT2.pdf

All GRBAlpha detections are listed at: https://monoceros.physics.muni.cz/hea/GRBAlpha/ 
GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume. 

All VZLUSAT-2 detections are listed at: https://monoceros.physics.muni.cz/hea/VZLUSAT-2/
The GRB detectors on VZLUSAT-2 are a demonstration payload for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). Two GRB modules of VZLUSAT-2 are placed in a perpendicular manner and each consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~30 keV to ~1000 keV. VZLUSAT-2 was launched on 2022 January 13 from Cape Canaveral.


GRB_name: GRB230521A
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33906
SUBJECT: GRB 230521A: VZLUSAT-2 detection
DATE:    23/06/02 17:43:46 GMT
FROM:    Marianna DafÄÃ­kovÃ¡ at Masaryk University <500025@mail.muni.cz>

M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory),  N. Werner  (Masaryk U.), M. Ohno (Hiroshima U.),  L. Meszaros, B. Csak (Konkoly Observatory), H. Takahashi (Hiroshima U.), F. Munz , M. Topinka, F. Hroch, N. Husarikova, J.-P. Breuer (Masaryk U.), J. Hudec, J. Kapus, M. Frajt, M. Rezenov (Spacemanic s.r.o), R. Laszlo (Needronix), G. Galgoczi (Wigner Research Center/Eotvos U.), N. Uchida (ISAS/JAXA), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), Y. Fukazawa, K. Hirose, H. Matake (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), L. L. Kiss (Konkoly Observatory),  T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), K. Torigoe (Hiroshima U.), P. Svoboda, V. Daniel, J. Dudas, M. Junas, J. Gromes (VZLU), I. Vertat (FEL ZCU)  -- the VZLUSAT-2/GRB payload collaboration.

The GRB detectors on board of the VZLUSAT-2 3U CubeSat (https://www.vzlusat2.cz/en/) detected a likely long-duration GRB 230521A. The event was triggered by Konus/Wind at 2023-05-21 18:52:04.019 UT and also observed by INTEGRAL/SPI-ACS at 2023-05-21 18:52:13 UT. The GOES-P X-ray flux does not show any increase at the time of this detection, therefore, it is unlikely to be a solar flare.

The data acquisition was performed by the GRB detector units no. 0 and no. 1. The detection was confirmed at the peak time 2023-05-21 18:52:10 UTC. The T90 duration is 45 s (46 s) and the significance during T90 reaches 11 sigma (16 sigma) for detector unit no. 0 (no. 1).

The light curve obtained by VZLUSAT-2 is available here:
https://vzlusat2.konkoly.hu/static/share/GRB230521A_GCN_VZLUSAT2.pdf

All VZLUSAT-2 detections are listed at: https://monoceros.physics.muni.cz/hea/VZLUSAT-2/
The GRB detectors on VZLUSAT-2 are a demonstration payload for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). Two GRB modules of VZLUSAT-2 are placed in a perpendicular manner and each consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~30 keV to ~1000 keV. VZLUSAT-2 was launched on 2022 January 13 from Cape Canaveral.


GRB_name: GRB230603A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33910
SUBJECT: GRB 230603A: Fermi GBM Final Real-time Localization
DATE:    23/06/03 12:45:56 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 12:35:29 UT on 3 Jun 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230603A (trigger 707488534.44648 / 230603525).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 294.5, Dec = -11.6 (J2000 degrees, equivalent to J2000 19h 37m, -11d 35'), with a statistical uncertainty of 3.6 degrees.

The angle from the Fermi LAT boresight is 38.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230603525/quicklook/glg_skymap_all_bn230603525.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230603525/quicklook/glg_healpix_all_bn230603525.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230603525/quicklook/glg_lc_medres34_bn230603525.gif


GRB_name: GRB230604A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33915
SUBJECT: GRB 230604A: AstroSat CZTI detection of a short GRB
DATE:    23/06/05 09:34:09 GMT
FROM:    Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>

G. Waratkar (IITB), P K. Navaneeth (IUCAA), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a short GRB 230604A which was also detected by KONUS-Wind (IPN_RAW Notices).

The source was clearly detected in the 20-200 keV energy range. The light curve peaks at 2023-06-04 05:53:48.0 UTC. The measured peak count rate associated with the burst is 669.5 (+184.9, -93.0) counts/s above the background in the combined data of all quadrants, with a total of 357 (+164, -169) counts. The local mean background count rate was 431.1 (+12.1, -15.6) counts/s. Using cumulative rates, we measure a T90 of 1.24 (+0.99, -0.73) s.

The source was also detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range.

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb


GRB_name: GRB230606A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33921
SUBJECT: GRB 230606A: Swift detection of a burst
DATE:    23/06/06 01:15:46 GMT
FROM:    David Palmer at LANL <palmer@lanl.gov>


A. Y. Lien (U Tampa), J.D. Gropp (PSU), J. A. Kennea (PSU),
D. M. Palmer (LANL), T. M. Parsotan (GSFC/UMBC/CRESSTII) and
B. Sbarufatti (INAF-OAB) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 00:14:37 the Swift Burst Alert Telescope (BAT) triggered and
located GRB 230606A (trigger=1173731).  Due to communications problems
from a recent typhoon in Guam, only limited real-time data is
available and notices are being delayed. Swift had a delayed slew
to the burst, presumably due to observing constraints. 
The ground-calculated BAT location based on available data is
RA, Dec 166.7956  36.5090. 
There is no immediately-available BAT lightcurve data for
this GRB, however the BAT trigger duration was on the 2 second
timescale, suggesting a long GRB. 

Using promptly downlinked data we find an uncatalogued X-ray source
located at RA, Dec 166.81107, 36.48427 which is equivalent to:
   RA(J2000)  = 11h 07m 14.66s
   Dec(J2000) = +36d 29' 03.4"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
position may be improved as more data are received; the latest position
is available at https://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (2.32 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 4
(+2.97/-2.57) x 10^21 cm^-2 (90% confidence). 

Further information will be available after the complete data
download at the next ground pass. 

Burst Advocate for this burst is A. Y. Lien (yarleen AT gmail.com). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)


GRB_name: GRB230606A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33924
SUBJECT: GRB 230606A: Enhanced Swift-XRT position
DATE:    23/06/06 06:08:02 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 1707 s of XRT Photon Counting mode data and 4 UVOT
images for GRB 230606A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 166.80951, +36.48425 which is equivalent
to:

RA (J2000): 11h 07m 14.28s
Dec (J2000): +36d 29' 03.3"

with an uncertainty of 2.2 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB230606A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33926
SUBJECT: GRB 230606A: Swift/UVOT Upper Limits
DATE:    23/06/06 13:18:49 GMT
FROM:    Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL) and A. Y. Lien (U. Tampa) report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 230606A 2784 s after the BAT trigger (Lien et al., GCN Circ. 33921).
No optical afterglow consistent with the XRT position (Goad et al., GCN Circ. 33924) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC          2784         2934          147         >20.3
white             2784         3554          344         >21.1
v                 3765         3965          197         >19.2
b                 3149         3349          197         >20.2
u                 2943         4514          328         >20.1
w1                4176         4376          197         >20.2
w2                3560         3760          197         >20.3

The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.015 in the direction of the burst (Schlegel et al. 1998).


GRB_name: GRB230604A
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33927
SUBJECT: GRB 230604A: GRBAlpha detection
DATE:    23/06/06 14:59:22 GMT
FROM:    Marianna DafÄÃ­kovÃ¡ at Masaryk University <500025@mail.muni.cz>

M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory), N. Werner (Masaryk U.), M. Ohno, H. Takahashi (Hiroshima U.), L. Meszaros, B. Csak (Konkoly Observatory), N. Husarikova, F. Munz , M. Topinka, M. Kolar, J.-P. Breuer, F. Hroch (Masaryk U.), T. Urbanec, M. Kasal,  A. Povalac (Brno U. of Technology), J. Hudec, J. Kapus, M. Frajt (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix s.r.o), M. Smelko, P. Hanak, P. Lipovsky (Technical U. of Kosice), G. Galgoczi (Wigner Research Center/Eotvos U.), Y. Uchida, H. Poon, H. Matake (Hiroshima U.), N. Uchida (ISAS/JAXA), T. Bozoki (Eotvos U.), G. Dalya (Eotvos U.), yyT. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), G. Friss (Eotvos U.), Y. Fukazawa, K. Hirose (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), K. Kapas (Eotvos U.), L. L. Kiss (Konkoly Observatory),  T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), J. Takatsy (Eotvos U.), K. Torigoe (Hiroshima U.), N. Kogiso, M. Yoneyama (Osaka Metropolitan U.), M. Moritaki (U. Tokyo), T. Kano (U. Michigan) -- the GRBAlpha collaboration.

The short-duration GRB 230604A (AstroSat detection: GCN 33915; INTEGRAL/SPI-ACS trigger at 2023-06-04 05:53:48 UT) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023; arXiv:2302.10048).

The detection was confirmed at the peak time 2023-06-04 05:53:48 UTC. The light curve observed by GRBAlpha shows a spike within one 1 s bin where the SNR reaches 6.6 sigma.

The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB230604A_GCN.pdf

All GRBAlpha detections are listed at: https://monoceros.physics.muni.cz/hea/GRBAlpha/ 
GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume. 


GRB_name: GRB230606A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33928
SUBJECT: GRB 230606A: Swift-XRT refined Analysis
DATE:    23/06/06 15:33:51 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), M.G. Bernardini
(INAF-OAB), A. Tohuvavohu (U. Toronto), D.N. Burrows (PSU), J. D. Gropp
(PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), P.A.
Evans (U. Leicester) report on behalf of the Swift-XRT team:

We have analysed 6.8 ks of XRT data for GRB 230606A, from 2.8 ks to
43.5 ks after the  BAT trigger. The data are entirely in Photon
Counting (PC) mode. 

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.16 (+0.09, -0.08).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.05 (+0.18, -0.17). The
best-fitting absorption column is  1.2 (+0.5, -0.4) x 10^21 cm^-2, in
excess of the Galactic value of 2.3 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.3 x 10^-11 (4.2 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.2 (+0.5, -0.4) x 10^21 cm^-2
Galactic foreground: 2.3 x 10^20 cm^-2
Excess significance: 3.7 sigma
Photon index:      2.05 (+0.18, -0.17)

If the light curve continues to decay with a power-law decay index of
1.16, the count rate at T+24 hours will be 0.010 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.3 x
10^-13 (4.3 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01173731.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB230606A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33930
SUBJECT: GRB 230606A: BOOTES-5/JGT optical upper limit
DATE:    23/06/06 17:14:28 GMT
FROM:    Youdong HU at IAA-CSIC <huyoudong072@hotmail.com>

Y.-D. Hu, E. Fernandez-Garcia, A. J. Castro-Tirado, I. Perez-Garcia, M.D. Caballero-Garcia, R. Sanchez-Ramirez, S. Guziy (IAA-CSIC), D. Hiriart and W. H. Lee (UNAM), C. J. Perez del Pulgar (UMA) and I. M. Carrasco-Garcia (SMA) and I. H. Park (SKKU), on behalf of a larger collaboration, report: 

Following the detection of GRB 230606A by Swift (Lien et al. GCNC 33921), we triggered the BOOTES-5/JGT 0.6m robotic telescope at Observatorio Astronomico Nacional in San Pedro Martir (Mexico) to observe the GRB location starting on Jun. 06, 04:27:09 UT (~ 4.2 hrs after trigger). A series of images in clear filter were gathered. No new optical source is detected within the enhanced Swift/XRT error region (Goad et al. GCNC 33924) down to 20.3 mag, which is consistent with the limits reported by UVOT (Breeveld et al. GCNC 33926).

We thank the staff at Observatorio Astronomico Nacional in San Pedro Martir for their excellent support.


GRB_name: GRB230606A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33931
SUBJECT: GRB 230606A: Fermi GBM Observation
DATE:    23/06/06 20:43:59 GMT
FROM:    Sarah Dalessi at UAH <sd0104@uah.edu>

S. Dalessi (UAH) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team:

"At 00:14:38.13 UT on 06 June 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230606A (trigger 707703283/230606010).
which was also detected by Swift BAT (A. Y. Lien et al. 2023, GCN 33921).
The Fermi GBM on-ground location is consistent with the Swift BAT position.

The angle from the Fermi LAT boresight is 110 degrees.

The GBM light curve consists of multiple peaks with a duration (T90)
of about 16 s (50-300 keV). The time-averaged spectrum
from T0-1.8 to T0+18.7 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -0.7 +/- 0.2 and the cutoff energy,
parameterized as Epeak, is 148 +/- 22 keV.

The event fluence (10-1000 keV) in this time interval is
(2.5 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+2.4 s in the 10-1000 keV band is 3.4 +/- 0.3 ph/s/cm^2.

A Band function fits the spectrum equally well
with Epeak= 98 +/- 25 keV, alpha = -0.2 +/- 0.5 and beta = -2.1 +/- 0.2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"


GRB_name: GRB230606A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33932
SUBJECT: GRB 230606A: Gaoyazi/GOT optical upper limit
DATE:    23/06/07 02:16:11 GMT
FROM:    Dong Xu at NAOC/CAS <dxu@nao.cas.cn>

S.Y. Fu, T.H. Lu, S.Q. Jiang, X. Liu, Z.P. Zhu, D Xu (NAOC), S.W. Luo, M.M. Yang, Z. K. Feng (GYZO, NAOC) report:

We observed the field of GRB 230606A detected by Swift (Lien et al., GCN 33921) with the GOT-0.5m telescope located at Gaoyazi, Xinjiang, China. We obtained 20x180 s frames in the Sloan r-band and 15x180 s frames in the Sloan z-band, starting at 16:25:45 UT on 2023-06-06, i.e., 16.18 hr after the Swift/BAT trigger.

No optical source is detected in our stacked images at the enhanced XRT position (Goad et al., GCN 33924), and preliminary photometric results are as follows:

T_mid-T0 (hr)    Filter   Upper_Limit (3-sigma)
    16.74                r          >20.9
    18.05                z          >18.1

calibrated with the nearby PanSTARRS field and not corrected for Galactic extinction.


GRB_name: GRB230606A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33933
SUBJECT: GRB 230606A: Swift-BAT refined analysis
DATE:    23/06/07 17:04:23 GMT
FROM:    Amy Lien at GSFC <amy.y.lien@nasa.gov>

A. Y. Lien (U Tampa), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU),
M. Stamatikos (OSU) (i.e. the Swift-BAT team):

Using the data set from T-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 230606A (trigger #1173731)
(Lien et al., GCN Circ. 33921).  The BAT ground-calculated position is
RA, Dec = 166.777, 36.504 deg which is
   RA(J2000)  =  11h 07m 06.4s
   Dec(J2000) = +36d 30' 15.6"
with an uncertainty of 2.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 15%.

The mask-weighted light curve shows two distinct pulses. The first pulse starts
at ~T0 and ends at ~T+4 s. The second pulse starts at ~T+14 s and ends at ~T+16 s.
T90 (15-350 keV) is 16.26 +- 1.29 sec (estimated error including systematics).

The time-averaged spectrum from T-0.26 to T+16.97 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.15 +- 0.30.  The fluence in the 15-150 keV band is 1.2 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+0.92 sec in the 15-150 keV band
is 2.6 +- 0.6 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1173731/BA/


GRB_name: GRB230506B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33935
SUBJECT: GRB 230506B: Chandra localization of the X-ray afterglow
DATE:    23/06/07 19:35:15 GMT
FROM:    Brendan O'Connor at UMD <oconnorb@umd.edu>

B. O'Connor (GWU), S. Dichiara (PSU), E. Troja (UTV), S. B. Cenko (NASA-GSFC, UMD), C. Kouveliotou (GWU), T. Sakamoto (AGU), A. Kutyrev (UMD), G. Ryan (Perimeter), R. Ricci (INAF), G. Bruni (INAF):

We carried out two Chandra ToO observation of GRB 230506B beginning on May 11, 2023 at 06:59:55 UT and June 01, 2023 at 19:31:19 UT with ACIS-S as part of program 24400201 (PI: O'Connor) for a total of 19 ks and 55 ks, respectively. The initial observation began ~4.8 days after the GRB trigger (Dichiara et al. GCN 33727). 

Within the XRT localization (Burrows et al. GCN 33737), we detect a single point source at RA, DEC = 21:47:55.6, 44:30:41.6 with an uncertainty of 0.9" (90% confidence, statistical + systematic). The source displays rapid fading between the two Chandra epochs confirming that it is the X-ray afterglow of GRB 230506B.

We would like to thank Patrick Slane, Harvey Tananbaum, Dan Schwartz, Scott Wolk, 
and the CXO staff for rapidly approving and planning this observation.


GRB_name: GRB230603A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33937
SUBJECT: Fermi GRB 230603A: Global MASTER-Net observations report
DATE:    23/06/07 21:03:51 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>

V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, 
G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov,  D.Cheryasov, Ya.Kechin
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev
(Irkutsk State University, API),

L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez 
(INAOE, Guillermo Haro Astrophysics Observatory),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

A. Gabovich, V.Yurkov 
(Blagoveschensk Educational State University)


MASTER-OAFA robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 230603A ( Fermi GBM team, GCN 33910) errorbox  1 days 62021 sec after notice time and 1 days 62028 sec after trigger time at 2023-06-05 05:49:18 UT, with upper limit up to  17.4 mag. The observations began at zenith distance = 28 deg. The sun  altitude  is -71.0 deg. 

The galactic latitude b = -16 deg., longitude l = 28 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2220782

We obtain a following upper limits.  

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

  148519 | 2023-06-05 05:49:18 |         MASTER-OAFA | (19h 36m 44.32s , -12d 09m 24.2s) |   C |   180 | 16.9 |        
  148699 | 2023-06-05 05:49:18 |         MASTER-OAFA | (19h 36m 44.32s , -12d 09m 24.2s) |   C |   540 | 17.4 |  Coadd 
  148730 | 2023-06-05 05:52:49 |         MASTER-OAFA | (19h 36m 49.42s , -12d 10m 24.5s) |   C |   180 | 16.9 |        
  148942 | 2023-06-05 05:56:21 |         MASTER-OAFA | (19h 36m 42.96s , -12d 11m 25.1s) |   C |   180 | 16.8 |        
  149797 | 2023-06-05 06:10:36 |         MASTER-OAFA | (19h 36m 48.72s , -12d 09m 29.5s) |   C |   180 | 15.5 |        
  150804 | 2023-06-05 06:27:23 |         MASTER-OAFA | (19h 36m 50.02s , -12d 11m 07.1s) |   C |   180 | 16.7 |        
  154240 | 2023-06-05 07:24:39 |         MASTER-OAFA | (19h 29m 31.33s , -14d 34m 07.0s) |   C |   180 | 16.9 |        
  155299 | 2023-06-05 07:42:18 |         MASTER-OAFA | (19h 29m 23.79s , -14d 32m 35.0s) |   C |   180 | 17.2 |        
  155934 | 2023-06-05 07:52:53 |         MASTER-OAFA | (19h 37m 42.65s , -14d 33m 21.1s) |   C |   180 | 16.9 |        
  165891 | 2023-06-05 10:38:50 |         MASTER-OAFA | (19h 21m 33.74s , -13d 31m 44.8s) |   C |   180 | 16.7 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.


GRB_name: GRB230608A
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33946
SUBJECT: GRB 230608A: AGILE detection
DATE:    23/06/09 11:20:47 GMT
FROM:    Francesco Longo at U of Trieste,INFN Trieste <franzlongo1969@gmail.com>

F. Longo (Univ. Trieste and INFN Trieste), F. Verrecchia, C. Pittori
(SSDC, and INAF/OAR),
M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata),  C. Casentini (INAF/IAPS),
A. Ursi (ASI and INAF/IAPS), A. Argan, M. Cardillo, Y. Evangelista, L. Foffano,
G. Piano (INAF/IAPS), A. Addis, L. Baroncelli, A. Bulgarelli, G. Panebianco,
A. Di Piano, V. Fioretti, N. Parmiggiani (INAF/OAS-Bologna), F.
Lucarelli (SSDC, and INAF/OAR),
M. Marisaldi (INAF/OAS-Bologna, and Bergen University),  M. Pilia, A.
Trois (INAF/OA-Cagliari),
I. Donnarumma, E. Menegoni (ASI), A. Giuliani (INAF/IASF-Mi), and P.
Tempesta (TeleSpazio)
report on behalf of the AGILE Team:

The AGILE satellite detected the GRB 230608A at T0 = 2023-06-08
18:34:36 s (UTC),
detected also by INTEGRAL SPI-ACS (trigger no.10282).

The burst is clearly visible in the AGILE scientific ratemeters of the
MiniCALorimeter (MCAL; 0.4-100 MeV), and AntiCoincidence (AC; 50-200 keV)
detectors.

The event lasted about 5 s and it released a total number
of 3966 counts in the MCAL detector (above a background rate of 532 Hz)
and 19256 counts in the AC-Top detector (above a background rate of 2875 Hz).
The AGILE ratemeters light curves can be found at

http://www.agilescienceapp.it/notices/GRB230608A_AGILE_RM_ND.png

Additional analysis of AGILE data is in progress.


GRB_name: GRB230608A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33947
SUBJECT: GRB 230608A: AstroSat CZTI detection
DATE:    23/06/09 12:20:14 GMT
FROM:    Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>



P K. Navaneeth (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data with the ML pipeline (Abraham et al., 2021, MNRAS, 504, 3084) and the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a bright GRB 230608A which was also detected by CALET (ID Num. 1370284460), INTEGRAL SPI-ACS (Trig Num. 10282), and AGILE (Longo et al., GCN Circ. 33946).

The source was clearly detected in the 20-200 keV energy range. The light curve peaks at 2023-06-08 18:34:37.50 UTC. The measured peak count rate associated with the burst is 724 (+54, -54) counts/s above the background in the combined data of three quadrants (out of four), with a total of 3349 (+393, -345) counts. The local mean background count rate was 358 (+2, -3) counts/s. Using cumulative rates, we measure a T90 of 16 (+8, -8) s.

The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2023-06-08 18:34:37.50 UTC. The measured peak count rate associated with the burst is 1210 (+85, -95) counts/s above the background in the combined data of all quadrants, with a total of 4297 (+722, -809) counts. The local mean background count rate was 1573 (+6, -7) counts/s. We measure a T90 of 7 (+7, -3) s from the cumulative Veto light curve.

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb


GRB_name: GRB230608A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33948
SUBJECT: GRB 230608A: CALET Gamma-Ray Burst Monitor detection
DATE:    23/06/10 04:09:51 GMT
FROM:    Yuta Kawakubo at Louisiana State University <kawakubo1@lsu.edu>

K. Yamaoka (Nagoya U), A. Yoshida, T. Sakamoto, 
S. Sugita (AGU), Y. Kawakubo (LSU), 
S. Nakahira (JAXA), Y. Asaoka (ICRR),
S. Torii, Y. Akaike, K. Kobayashi (Waseda U),
Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC),
M. L. Cherry (LSU), S. Ricciarini (U of Florence),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

The long GRB 230608A (INTEGRAL SPI ACS Trigger #10282;
AGILE detection: Longo et al., GCN Circ 33946; AstroSat CZTI
detection: Navaneeth et al., GCN Circ 33947) triggered the 
CALET Gamma-ray Burst Monitor (CGBM)  at 18:34:33.392 UTC 
on 8 June 2023
(http://cgbm.calet.jp/cgbm_trigger/flight/1370284460/index.html).
The burst signal was seen by only the SGM detector.

The burst light curve shows a single pulse that starts
at T+2.5 sec, peaks at T+3.3 sec, and ends at T+7.0 sec.
The T90 and T50 durations measured by the SGM data are 
3.9 +/- 0.4 sec and 1.6 +/- 0.4 sec (40-1000 keV), respectively.

The ground-processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1370284460/

The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.


GRB_name: GRB230606A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33956
SUBJECT: GRB 230606A: LCOGT Optical Observations
DATE:    23/06/13 14:33:09 GMT
FROM:    Robert Strausbaugh at University of Minnesota <rstrausb@umn.edu>

R. Strausbaugh (University of Minnesota), A. Cucchiara (NASA) report on
behalf of a larger collaboration:

We observed the GRB 230606A (Lien et al., GCN 33921) field with the LCOGT
1-meter Sinistro instrument at the McDonald Observatory, Texas, USA site,
on June 6, from 02:58 to 03:30 UT (corresponding to 2.73 to 3.27 hours from
the GRB trigger time) with the SDSS r and i filters.

We performed a series of 3x300s exposures in each band.  We detect an
uncataloged source within the Swift-XRT enhanced error region (Goad et al.,
GCN 33924).  Later time upper limits (Hu et al., GCN 33930) are consistent
with the fading of this source, suggesting that it is the optical
afterglow; however, the later upper limit could be a result of the redness
of this source.

The following magnitudes are calculated using the PanSTARRS catalog as
reference:

r > 20.95 +/- 0.06
i > 19.66 +/- 0.04

These magnitudes are not corrected for galactic extinction.


GRB_name: GRB230614A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33957
SUBJECT: GRB 230614A: Fermi GBM Final Real-time Localization
DATE:    23/06/14 00:22:41 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 00:12:15 UT on 14 Jun 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230614A (trigger 708394340.465878 / 230614009).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 131.6, Dec = 20.0 (J2000 degrees, equivalent to J2000 08h 46m, 20d 00'), with a statistical uncertainty of 7.4 degrees.

The angle from the Fermi LAT boresight is 64.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230614009/quicklook/glg_skymap_all_bn230614009.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230614009/quicklook/glg_healpix_all_bn230614009.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230614009/quicklook/glg_lc_medres34_bn230614009.gif


GRB_name: GRB230614B
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33958
SUBJECT: GRB 230614B: Fermi GBM Final Real-time Localization
DATE:    23/06/14 09:25:31 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 09:15:01 UT on 14 Jun 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230614B (trigger 708426906.627188 / 230614385).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 110.9, Dec = -61.9 (J2000 degrees, equivalent to J2000 07h 23m, -61d 53'), with a statistical uncertainty of 1.0 degrees.

The angle from the Fermi LAT boresight is 15.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230614385/quicklook/glg_skymap_all_bn230614385.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230614385/quicklook/glg_healpix_all_bn230614385.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230614385/quicklook/glg_lc_medres34_bn230614385.gif


GRB_name: GRB230614B
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33960
SUBJECT: GRB 230614B: Swift/BAT-GUANO detection outside the coded FOV 
DATE:    23/06/14 16:17:40 GMT
FROM:    Jimmy DeLaunay at University of Alabama  <delauj2@gmail.com>

James DeLaunay (U Alabama), Samuele Ronchini (PSU), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Aaron Tohuvavohu (U Toronto) report: 

Swift/BAT did not localize GRB 230614B onboard (T0: 2023-06-14T09:15:01 UTC, Fermi/GBM trig 708426906, GCN 33958) 

The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). 

Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground. 

The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), detects the burst with a sqrt(TS) of 16.18 in a 4.096 s analysis time bin. 
NITRATES results are consistent with a burst coming from outside the FOV, with DeltaLLHOut of 1.
The Fermi/GBM localization is consistent with being outside the BAT FOV (GCN 33958). 

See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descriptions and interpretation of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut. 

GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. 

A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/


GRB_name: GRB230614C
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33966
SUBJECT: GRB 230614C: Fermi GBM Detection
DATE:    23/06/15 08:25:05 GMT
FROM:    R. Hamburg at CNRS/IJCLab <rachel.k.hamburg@gmail.com>

S. Lesage (UAH), R. Hamburg (CNRS/ICJLab) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 10:10:31 UT on 14 June 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230614C (trigger 708430236/230614424) which 
was also detected by INTEGRAL SPI-ACS (trigger 10284).

The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 229.21, Dec = 10.30 (J2000 degrees, equivalent to
J2000 15h 16m, +10d 18'), with a statistical uncertainty of 1.00 degree
(radius, 1-sigma containment, statistical only; there is additionally a systematic error
which we have characterized as a core-plus-tail model, with 90% of GRBs having a
3.7 deg error and a small tail suffering a larger than 10 deg systematic error
[Connaughton et al. 2015, ApJS, 216, 32]).

The angle from the Fermi LAT boresight is 108 degrees.

The GBM light curve consists of a single emission episode with a duration (T90)
of about 6.1 s (50-300 keV). The time-averaged spectrum
from T0+0.003 to T0+7.488 s is best fit by
a Band function with Epeak = 196 +/- 7 keV,
alpha = -0.50 +/- 0.04, and beta = -2.44 +/- 0.08.

The event fluence (10-1000 keV) in this time interval is
(4.04 +/- 0.06)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+1.8 s in the 10-1000 keV band is 32.6 +/- 0.5 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"


GRB_name: GRB230614B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33967
SUBJECT: GRB 230614B: Fermi GBM Observation
DATE:    23/06/15 14:01:13 GMT
FROM:    R. Hamburg at CNRS/IJCLab <rachel.k.hamburg@gmail.com>

R. Hamburg (CNRS/IJCLab) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 09:15:01.63 UT on 14 June 2023, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 230614B (trigger 708426906 / 230614385),
which was also detected by Swift/BAT-GUANO (DeLaunay et al. 2023, GCN 33960).
The Fermi GBM Final Real-time Localization was reported in GCN 33958.

The angle from the Fermi LAT boresight at the GBM trigger time is 15 degrees.

The GBM light curve consists of two main pulses with a duration (T90)
of about 15 s (50-300 keV). The time-averaged spectrum from T0-2.43 s 
to T0+18.05 s is best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.18 +/- 0.05 and
the cutoff energy, parameterized as Epeak, is 115 +/- 6 keV.

The event fluence (10-1000 keV) in this time interval is
(5.94 +/- 0.16)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+1.47 s in the 10-1000 keV band
is 10.3 +/- 0.3 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"


GRB_name: GRB230614C
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33969
SUBJECT: GRB 230614C: AstroSat CZTI detection
DATE:    23/06/15 18:30:32 GMT
FROM:    Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>

P K. Navaneeth (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long GRB 230614C which was also detected by Fermi GBM (Lesage et al., GCN Circ. 33966), and INTEGRAL SPI-ACS (Trigger 10284).

The source was clearly detected in the 20-200 keV energy range. The light curve peaks at 2023-06-14 10:10:33.25 UTC. The measured peak count rate associated with the burst is 2133 (+308, -123) counts/s above the background in the combined data of all quadrants, with a total of 5394 (+562, -588) counts. The local mean background count rate was 456 (+9, -12) counts/s. Using cumulative rates, we measure a T90 of 5.1 (+1.3, -1.2) s. In the preliminary analysis, we find 423 Compton events associated with this event.

The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2023-06-14 10:10:33.25 UTC. The measured peak count rate associated with the burst is 2148 (+98, -105) counts/s above the background in the combined data of all quadrants, with a total of 5536 (+476, -514) counts. The local mean background count rate was 1459 (+7, -8) counts/s. We measure a T90 of 5.2 (+4.1, -1.5) s from the cumulative Veto light curve.

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb


GRB_name: GRB230616A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33982
SUBJECT: GRB 230616A: Swift/BAT-GUANO detection of a short burst outside the coded FOV 
DATE:    23/06/17 03:52:13 GMT
FROM:    Aaron Tohuvavohu at University of Toronto <aaron.tohu@gmail.com>

Aaron Tohuvavohu (U Toronto), James DeLaunay (U Alabama), Samuele Ronchini (PSU), Gayathri Raman (PSU), Jamie A. Kennea (PSU) report: 

Swift/BAT did not localize GRB 230616A onboard (T0: 2023-06-16T20:37:56.8 UTC, INTEGRAL trig 10287) 

The INTEGRAL notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). 

Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 90 seconds of BAT event-mode data from [-45,+45] seconds around the time of the burst. All the requested event mode data was delivered to the ground. 

The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), detects the burst with a sqrt(TS) of 29.2 in a 0.128 s analysis time bin. 

NITRATES results are consistent with a burst coming from outside the FOV, with DeltaLLHOut of -1.

See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descriptions and interpretation of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut. 

GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. 

A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/


GRB_name: GRB230616A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33983
SUBJECT: GRB 230616A: AstroSat CZTI detection
DATE:    23/06/17 05:57:29 GMT
FROM:    Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>

G. Waratkar (IITB), P K. Navaneeth (IUCAA), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a bright short GRB 230616A which was also detected by INTEGRAL/SPI-ACS (Trig 10287) and Swift/BAT-GUANO (Tohuvavohu et al., GCN Circ. 33982).

The source was clearly detected in the 20-200 keV energy range. The light curve peaks at 2023-06-16 20:37:58.765 UTC. The measured peak count rate associated with the burst is 6385 (+1349, -1043) counts/s above the background in the combined data of all quadrants, with a total of 307 (+42, -47) counts. The local mean background count rate was 431 (+29, -43) counts/s. Using cumulative rates, we measure a T90 of 0.06 (+0.01, -0.01) s.

The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range.

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb


GRB_name: GRB230614C
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33984
SUBJECT: GRB 230614C: GRBAlpha detection
DATE:    23/06/17 07:27:40 GMT
FROM:    Marianna DafÄÃ­kovÃ¡ at Masaryk University <500025@mail.muni.cz>

M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory), N. Werner (Masaryk U.), M. Ohno, H. Takahashi (Hiroshima U.), L. Meszaros, B. Csak (Konkoly Observatory), N. Husarikova, F. Munz , M. Topinka, M. Kolar, J.-P. Breuer, F. Hroch (Masaryk U.), T. Urbanec, M. Kasal, A. Povalac (Brno U. of Technology), J. Hudec, J. Kapus, M. Frajt (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix s.r.o), M. Smelko, P. Hanak, P. Lipovsky (Technical
U. of Kosice), G. Galgoczi (Wigner Research Center/Eotvos U.), Y. Uchida, H. Poon, H.
Matake (Hiroshima U.), N. Uchida (ISAS/JAXA), T. Bozoki (Eotvos U.), G. Dalya (Eotvos U.), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), G. Friss (Eotvos U.), Y. Fukazawa, K. Hirose (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), K. Kapas (Eotvos U.), L. L. Kiss (Konkoly Observatory), T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), J. Takatsy (Eotvos U.), K. Torigoe (Hiroshima U.), N. Kogiso, M. Yoneyama (Osaka Metropolitan U.), M. Moritaki (U. Tokyo), T. Kano (U. Michigan) -- the
GRBAlpha collaboration.

The long-duration GRB 230614C (Fermi/GBM detection: GCN 33966; AstroSat detection: GCN 33969; INTEGRAL/SPI-ACS detection: trigger no. 10284) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023; arXiv:2302.10048).

The detection was confirmed at the peak time 2023-06-14 10:10:32 UTC. The T90 duration measured by GRBAlpha is 6 s and the overall significance during T90 reaches 43 sigma.

The light curve obtained by GRBAlpha is available here:
https://grbalpha.konkoly.hu/static/share/GRB230614C_GCN.pdf

All GRBAlpha detections are listed at: https://monoceros.physics.muni.cz/hea/GRBAlpha/
GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume.


GRB_name: GRB230617A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33987
SUBJECT: GRB 230617A: Fermi GBM Final Real-time Localization
DATE:    23/06/17 22:23:59 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely SHORT GRB

At 22:13:31 UT on 17 Jun 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230617A (trigger 708732816.996698 / 230617926).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 139.4, Dec = -70.5 (J2000 degrees, equivalent to J2000 09h 17m, -70d 30'), with a statistical uncertainty of 25.5 degrees.

The angle from the Fermi LAT boresight is 90.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230617926/quicklook/glg_skymap_all_bn230617926.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230617926/quicklook/glg_healpix_all_bn230617926.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230617926/quicklook/glg_lc_medres34_bn230617926.gif


GRB_name: GRB230616A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33988
SUBJECT: GRB 230616A: Swift ToO observations
DATE:    23/06/18 03:33:14 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

P. A. Evans (U. Leicester) reports on behalf of the Swift team:

Swift has initiated a ToO observation of the IPN GRB 230616A. 
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021576

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the IPN event. Any X-ray source
considered to be a probable afterglow candidate will be reported via a 
GCN Circular after manual consideration.

Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).

This circular is an official product of the Swift-XRT team.


GRB_name: GRB230618A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33989
SUBJECT: GRB 230618A: Swift detection of a burst
DATE:    23/06/18 04:09:22 GMT
FROM:    David Palmer at LANL <palmer@lanl.gov>


K. L. Page (U Leicester) and S. Laha (GSFC/UMBC) report on behalf of
the Neil Gehrels Swift Observatory Team:

At 03:51:12 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 230618A (trigger=1175438).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is   
RA, Dec 196.588, +3.306 which is 
   RA(J2000) = 13h 06m 21s
   Dec(J2000) = +03d 18' 20"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  Due to a telemetry outage caused by
a recent storm in Guam, no further BAT data will be available
until a ground station pass. 

Using promptly downlinked data we find a bright, uncatalogued X-ray
source located at RA, Dec 196.60313, 3.30257 which is equivalent to:
   RA(J2000)  = 13h 06m 24.75s
   Dec(J2000) = +03d 18' 09.3"
with an uncertainty of 5.8 arcseconds (radius, 90% containment). This
position may be improved as more data are received; the latest position
is available at https://www.swift.ac.uk/sper. No spectrum from the
promptly downlinked event data is yet available to determine the column
density. 

The initial flux in the 2.5 s image was 6.46e-10 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of nominal 150.000 seconds with the White
filter starting 137 seconds after the BAT trigger. No credible afterglow
candidate has been found in the initial data products. Data from the 2.7'x2.7'
sub-image are not available at this time. The 8'x8' region for the list of
sources generated on-board covers 100% of the XRT error circle. The list of
sources is typically complete to about 18 mag. No correction has been made for
the expected extinction corresponding to E(B-V) of 0.025. 

Burst Advocate for this burst is K. L. Page (klp5 AT leicester.ac.uk). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)


GRB_name: GRB230618A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33990
SUBJECT: GRB 230618A: Prompt enhanced Swift-XRT position
DATE:    23/06/18 04:31:34 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:

Using  promptly downlinked XRT event data for GRB 230618A, we find an
enhanced XRT position of the afterglow: RA, Dec: 196.60310, 3.30343
which is equivalent to:
   RA (J2000)  = 13 06 24.74
   Dec (J2000) = +03 18 12.3
with an uncertainty of 1.9 arcseconds (radius, 90% confidence).
Analysis of the promptly available data is online at
http://www.swift.ac.uk/sper/1175438.

Position enhancement is is described by Goad et al. (2007, A&A, 476,
1401) and Evans et al. (2009, MNRAS, 397, 1177).

This circular is an official product of the Swift-XRT team.


GRB_name: GRB230618B
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33991
SUBJECT: GRB 230618B: Fermi GBM Final Real-time Localization
DATE:    23/06/18 05:37:37 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 05:26:11 UT on 18 Jun 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230618B (trigger 708758776.929754 / 230618227).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 257.5, Dec = -6.7 (J2000 degrees, equivalent to J2000 17h 10m, -6d 42'), with a statistical uncertainty of 1.0 degrees.

The angle from the Fermi LAT boresight is 90.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230618227/quicklook/glg_skymap_all_bn230618227.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230618227/quicklook/glg_healpix_all_bn230618227.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230618227/quicklook/glg_lc_medres34_bn230618227.gif


GRB_name: GRB230618A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33992
SUBJECT: GRB230618A: LCOGT Optical Observations
DATE:    23/06/18 06:19:09 GMT
FROM:    Robert Strausbaugh at University of Minnesota <rstrausb@umn.edu>

R. Strausbaugh (University of Minnesota), A. Cucchiara (NASA) report on
behalf of a larger collaboration:

We observed the GRB 230618A (Page et al., GCN 33989) field with the LCOGT
1-meter Sinistro instrument at the McDonald Observatory, Texas, USA site,
on June 18, from 04:31 to 05:03 UT (corresponding to 0.33 to 1.20 hours
from the GRB trigger time) with the SDSS r and i filters.

We performed a series of 3x300s exposures in each band.  We detect an
uncatalouged source within the Swift-XRT enhanced error region (P.A. Evans
et al., GCN 33990).

The following magnitudes are calculated using the PanSTARRS catalog as
reference:

r = 20.62 +/- 0.02
i = 19.16 +/- 0.02

These magnitudes are not corrected for galactic extinction.


GRB_name: GRB230618A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  33994
SUBJECT: Swift GRB 230618A: Global MASTER-Net observations report
DATE:    23/06/18 06:40:49 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>

V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, 
G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov,  D.Cheryasov, Ya.Kechin
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev
(Irkutsk State University, API),

L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez 
(INAOE, Guillermo Haro Astrophysics Observatory),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

A. Gabovich, V.Yurkov 
(Blagoveschensk Educational State University)


MASTER-OAFA robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Argentina (OAFA observatory of San Juan National University) was pointed to the Swift GRB 230618A ( K. L. Page (U Leicester) and S. Laha (GSFC/UMBC) report on behalf of et al., GCN 33989) errorbox  10 sec after notice time and 42 sec after trigger time at 2023-06-18 03:54:03 UT, with upper limit up to  19.5 mag. The observations began at zenith distance = 67 deg. The sun  altitude  is -78.0 deg. 

The galactic latitude b = 66 deg., longitude l = 314 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2224051

We obtain a following upper limits.  

Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

      48 |         MASTER-OAFA |   C |    10 | 16.9 |        
      79 |             MASTER- |   C |    10 | 15.6 |        
      89 |         MASTER-OAFA |   C |    10 | 16.9 |        
     113 |             MASTER- |   C |    20 | 16.1 |        
     135 |         MASTER-OAFA |   C |    20 | 17.3 |        
     158 |             MASTER- |   C |    30 | 16.5 |        
     191 |         MASTER-OAFA |   C |    30 | 17.7 |        
     241 |         MASTER-OAFA |   C |   130 | 18.7 |  Coadd 
     213 |             MASTER- |   C |    40 | 16.6 |        
     258 |         MASTER-OAFA |   C |    40 | 17.9 |        
     278 |             MASTER- |   C |    50 | 16.7 |        
     339 |         MASTER-OAFA |   C |    60 | 18.2 |        
     353 |             MASTER- |   C |    60 | 17.1 |        
     440 |         MASTER-OAFA |   C |    80 | 18.5 |        
     555 |         MASTER-OAFA |   C |   310 | 19.3 |  Coadd 
     443 |             MASTER- |   C |    80 | 17.1 |        
     553 |             MASTER- |   C |   100 | 17.1 |        
     561 |         MASTER-OAFA |   C |   100 | 18.6 |        
     683 |             MASTER- |   C |   120 | 17.1 |        
     708 |         MASTER-OAFA |   C |   130 | 18.7 |        
     838 |             MASTER- |   C |   150 | 17.2 |        
     884 |         MASTER-OAFA |   C |   160 | 18.7 |        
    1064 |         MASTER-OAFA |   C |   520 | 19.5 |  Coadd 
    1023 |             MASTER- |   C |   180 | 17.5 |        
    1085 |         MASTER-OAFA |   C |   180 | 18.6 |        
    1222 |             MASTER- |   C |   180 | 17.1 |        
    1297 |         MASTER-OAFA |   C |   180 | 18.8 |        
    1422 |             MASTER- |   C |   180 | 17.1 |        
    1508 |         MASTER-OAFA |   C |   180 | 18.6 |        
    1688 |         MASTER-OAFA |   C |   540 | 19.3 |  Coadd 
    1622 |             MASTER- |   C |   180 | 17.1 |        
    1822 |             MASTER- |   C |   180 | 17.1 |        
    1902 |         MASTER-OAFA |   C |   180 | 18.5 |        
    2097 |             MASTER- |   C |   180 | 17.0 |        
    2114 |         MASTER-OAFA |   C |   180 | 18.5 |        
    2325 |         MASTER-OAFA |   C |   180 | 18.3 |        
    2505 |         MASTER-OAFA |   C |   540 | 19.0 |  Coadd 
    2438 |             MASTER- |   C |   180 | 17.5 |        
    2536 |         MASTER-OAFA |   C |   180 | 18.5 |        
    2747 |         MASTER-OAFA |   C |   180 | 18.3 |        
    2778 |             MASTER- |   C |   180 | 17.4 |        
    2958 |         MASTER-OAFA |   C |   180 | 18.1 |        
    3118 |             MASTER- |   C |   180 | 17.4 |        
    3170 |         MASTER-OAFA |   C |   180 | 17.9 |        
    3381 |         MASTER-OAFA |   C |   180 | 17.9 |        
    3458 |             MASTER- |   C |   180 | 17.4 |        
    3799 |             MASTER- |   C |   180 | 17.5 |        
    3947 |         MASTER-OAFA |   C |   180 | 17.7 |        
    4138 |             MASTER- |   C |   180 | 17.5 |        
    4158 |         MASTER-OAFA |   C |   180 | 17.7 |        
    4477 |             MASTER- |   C |   180 | 17.5 |        
    4551 |         MASTER-OAFA |   C |   180 | 17.4 |        
    4763 |         MASTER-OAFA |   C |   180 | 17.3 |        
    4817 |             MASTER- |   C |   180 | 17.4 |        
    5011 |         MASTER-OAFA |   C |   180 | 17.0 |        
    5158 |             MASTER- |   C |   180 | 17.5 |        
    5222 |         MASTER-OAFA |   C |   180 | 16.9 |        
    5499 |             MASTER- |   C |   180 | 17.4 |        
    5795 |         MASTER-OAFA |   C |   180 | 16.5 |        
    5837 |             MASTER- |   C |   180 | 17.5 |        
    6177 |             MASTER- |   C |   180 | 17.5 |        
    6516 |             MASTER- |   C |   180 | 17.5 |        
    6856 |             MASTER- |   C |   180 | 17.5 |        
    7197 |             MASTER- |   C |   180 | 17.5 |        
    7537 |             MASTER- |   C |   180 | 17.5 |        
    7877 |             MASTER- |   C |   180 | 17.5 |        
    8218 |             MASTER- |   C |   180 | 17.5 |        
    8558 |             MASTER- |   C |   180 | 17.5 |        
    8899 |             MASTER- |   C |   180 | 17.5 |        
    9240 |             MASTER- |   C |   180 | 17.5 |        
    9581 |             MASTER- |   C |   180 | 17.5 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.


GRB_name: GRB230618A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34001
SUBJECT: GRB 230618A: KAIT Optical Observations
DATE:    23/06/18 09:20:07 GMT
FROM:    Weikang Zheng at UC Berkeley <weikang@berkeley.edu>

WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on

behalf of the KAIT GRB team:


The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at

Lick Observatory, responded to GRB 230618A detected by Swift

(Page et al., GCN 33989) starting at 04:31:35 UT, about 0.69 hours

after the bust. Observations were performed in the clear (roughly R)

filter, and the exposure time was 60s per image, with a total of 31

images were obtained. We marginally detected the optical afterglow

reported by Strausbaugh et al. (GCN 33992) in our coadd image

in clear band, which we measured its brightness of 20.8 +/- 0.3 mag

at a mid time of ~0.79 hours after the burst, calibrated to the

Pan-STARRS1 catalog.


GRB_name: GRB230616A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34006
SUBJECT: GRB 230616A: Swift-XRT observations
DATE:    23/06/18 15:39:42 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), D.N. Burrows (PSU),
J. D. Gropp (PSU), S. Dichiara (PSU), A.P. Beardmore (U. Leicester),
J.P. Osborne (U. Leicester), E. Ambrosi  (INAF-IASFPA) and P.A. Evans
(U. Leicester) report on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the IPN-detected
burst GRB 230616A in a series of observations tiled on the sky. The
total exposure time is 4.6 ks, distributed over 4 tiles; the maximum
exposure at a single sky location was 2.0 ks. The data were collected
between T0+111.3 ks and T0+140.7 ks, and are entirely in Photon
Counting (PC) mode. 

Three uncatalogued X-ray sources have been detected, however none of
them is above the RASS limit or shows definitive signs of fading.
Therefore, at the present time we cannot identify which, if any, is the
afterglow. Details of these sources are given below:

Source 1:
  RA (J2000):  192.1005  =  12:48:24.12
  Dec (J2000): +5.4365  =  +05:26:11.4
  Error: 8.2 arcsec (radius, 90% conf.)
  Count-rate: 0.0177 [+0.0053, -0.0045] ct s^-1   
  Distance: 1675 arcsec from IPN position.
  Flux: (6.8 [+2.1, -1.7])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 2:
  RA (J2000):  192.2299  =  12:48:55.18
  Dec (J2000): +6.0936  =  +06:05:36.9
  Error: 5.1 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: 0.0125 [+0.0046, -0.0037] ct s^-1   
  Distance: 820 arcsec from IPN position.
  Flux: (4.2 [+1.5, -1.3])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 3:
  RA (J2000):  191.8031  =  12:47:12.74
  Dec (J2000): +5.5136  =  +05:30:48.9
  Error: 6.0 arcsec (radius, 90% conf.)
  Count-rate: (5.7 [+3.5, -2.5])e-3 ct s^-1   
  Distance: 1769 arcsec from IPN position.

The results of the XRT-team automatic analysis of the tiled XRT
observations, including a position-specific upper limit calculator, are
available at https://www.swift.ac.uk/xrt_products/TILED_GRB00112.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB230618A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34007
SUBJECT: GRB 230618A: Swift-XRT refined Analysis
DATE:    23/06/18 15:56:45 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

M.G. Bernardini (INAF-OAB), J. D. Gropp (PSU), S. Dichiara (PSU), J.A.
Kennea (PSU), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester),
K.L. Page (U. Leicester), E. Ambrosi  (INAF-IASFPA) , M. Capalbi
(INAF-IASFPA) report on behalf of the Swift-XRT team:

We have analysed 6.3 ks of XRT data for GRB 230618A, from 118 s to 30.0
ks after the  BAT trigger. The data comprise 157 s in Windowed Timing
(WT) mode (the first 9 s were taken while Swift was slewing) with the
remainder in Photon Counting (PC) mode. The best available XRT position
 (using the promptly downlinked event data, the XRT-UVOT alignment and
matching UVOT field sources to the USNO-B1 catalogue) is RA, Dec =
196.60531, 3.30238 which is equivalent to:

RA (J2000): 13 06 25.27
Dec(J2000): +03 18 08.6

with an uncertainty of 1.9 arcsec (radius, 90% confidence).

The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=1.10 (+0.13, -0.10). At T+594 s  the decay
steepens to an alpha of 2.90 (+0.40, -0.23) before breaking again at
T+3047 s to a final decay with index alpha=0.29 (+0.68, -0.29).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.55 (+0.13, -0.12). The
best-fitting absorption column is  1.4 (+0.5, -0.4) x 10^21 cm^-2, in
excess of the Galactic value of 2.1 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.73 (+/-0.17) and a
best-fitting absorption column of 2.1 (+0.7, -0.6) x 10^21 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 4.1 x 10^-11 (5.2 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      2.1 (+0.7, -0.6) x 10^21 cm^-2
Galactic foreground: 2.1 x 10^20 cm^-2
Excess significance: 5.0 sigma
Photon index:      1.73 (+/-0.17)

If the light curve continues to decay with a power-law decay index of
0.29, the count rate at T+24 hours will be 8.8 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.6 x
10^-13 (4.5 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01175438.

This circular is an official product of the Swift-XRT team.


