# GCN_circulars

GRB_name: GRB231117A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35128
SUBJECT: GRB 231117A: Swift-XRT refined Analysis
DATE:    23/11/19 19:28:53 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB), J.A. Kennea (PSU), A.
Tohuvavohu (U. Toronto), D.N. Burrows (PSU), A.P. Beardmore (U.
Leicester), J.P. Osborne (U. Leicester), P. D'Avanzo (INAF-OAB) and
P.A. Evans report on behalf of the Swift-XRT team:

We have analysed 8.8 ks of XRT data for GRB 231117A, from 85 s to 223.3
ks after the  BAT trigger. The data comprise 9 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=0.65 (+0.07, -0.06).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.81 (+0.17, -0.13). The
best-fitting absorption column is  consistent with the Galactic value
of 6.1 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 3.6 x 10^-11 (4.1 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      6.1 (+/-3.8) x 10^20 cm^-2
Galactic foreground: 6.1 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.81 (+0.17, -0.13)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01197027.

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


GRB_name: GRB231120A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35129
SUBJECT: GRB 231120A: Fermi GBM Final Real-time Localization
DATE:    23/11/20 00:32:39 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 00:23:08 UT on 20 Nov 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231120A (trigger 722132593.748426 / 231120016).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 50.7, Dec = 1.4 (J2000 degrees, equivalent to J2000 03h 22m, 1d 23'), with a statistical uncertainty of 18.2 degrees.

The angle from the Fermi LAT boresight is 73.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231120016/quicklook/glg_skymap_all_bn231120016.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/bn231120016/quicklook/glg_healpix_all_bn231120016.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231120016/quicklook/glg_lc_medres34_bn231120016.gif


GRB_name: GRB231118A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35131
SUBJECT: GRB 231118A: Fermi GBM observation
DATE:    23/11/20 03:17:28 GMT
FROM:    Lorenzo Scotton at UAH <lscottongcn@outlook.com>

C. de Barra (UCD) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 17:16:29.83 UT on 18 November 2023, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 231118A (trigger 722020594 / 231118720), 
which was also detected by Swift BAT (S. Laha et al. 2023, GCN 35101) 
and Swift XRT (K.L. Page & P.A. Evens, 2023, GCN 35104). 

The Fermi Final Localization was reported in GCN 35100 and is consistent 
with the Swift BAT and XRT positions.

The angle from the Fermi LAT boresight at the GBM trigger time is 118 degrees.

The GBM light curve consists of a single peak with a duration (T90) 
of about 6 s (50-300 keV). The time-averaged spectrum from -4.1s to 6.1 s is best fit 
with a Band function with Epeak = 217.7 +/- 22.6 keV, alpha = -0.77 +/- 0.07, 
and beta = -2.17 +/- 0.13

The event fluence (10-1000 keV) in this time interval is (1.0 +/- 0.1)E-05 erg/cm^2. 
The 1-sec peak photon flux measured starting from T0+3.2 s in the 10-1000 keV band 
is 18.0 +/- 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: GRB231118B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35132
SUBJECT: GRB 231118B: Fermi GBM observation
DATE:    23/11/20 03:32:59 GMT
FROM:    Lorenzo Scotton at UAH <lscottongcn@outlook.com>

C. de Barra (UCD) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 22:34:14.86 UT on 18 November 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 231118B (trigger 722039659/231118940).

The Fermi GBM Final Real-time Localization is reported in GCN 35111.
The angle from the Fermi LAT boresight is 83 degrees.

The GBM light curve consists of a single bright peak 
with a duration (T90) of about 6 s (50-300 keV). 
The time-averaged spectrum from T0+0.1 to T0+7.9 s 
is best fit by a Band function with Epeak = 127.9 +/- 3.4 keV, 
alpha = -0.36 +/- 0.04, and beta = -2.89 +/- 0.13

The event fluence (10-1000 keV) in this time interval is
(1.3 +/- 0.1)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+2.7 s in the 10-1000 keV band is 21.7 +/- 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: GRB231117A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35133
SUBJECT: GRB 231117A : MITSuME Akeno optical afterglow candidate detection
DATE:    23/11/20 12:14:35 GMT
FROM:    Ichiro Takahashi at Tokyo Tech <itakahashi@hp.phys.titech.ac.jp>

I. Takahashi, H. Takei, N. Higuchi, M. Sasada, M. Niwano, S. Sato, S. Hayatsu, H. Seki, Y. Yatsu and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration:

After our previous report (Takei et al., GCN 35076), we reanalyzed all of the GRB 231117A field data observed by the MITSuME 50 cm telescope Akeno on Nov. 17th, and the point source was presumably detected at the afterglow candidate position reported by Yang et al. (GCN 35083). Here we report the Rc-band magnitudes and the 3-sigma limits of the stacked images as follows.

T0+[hour] | MID-UT | T-EXP[sec] | magnitudes of forced-photometry | 3-sigma limits
-----------------------------------------------------------------------------------------------
6.38 | 2023-11-17 09:25:57 | 5160 | Rc=20.7+/-0.3 | g'>20.5, Rc>20.4, Ic>19.8
7.59 | 2023-11-17 10:38:29 | 10320 | Rc=20.7+/-0.2 | g'>20.8, Rc>20.7, Ic>20.1
-----------------------------------------------------------------------------------------------
T0+ : Elapsed time after the trigger
T-EXP: Total Exposure time
These magnitudes include the contribution from the underlying host galaxy.

We used the PS1 catalog for flux calibration. The catalog magnitudes in PS1 g, r and i bands were converted to our g'-, Rc- and Ic-band magnitudes following Tonry et al. (2012), Table 6. 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: GRB231117A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35134
SUBJECT: GRB231117A: Swift-UVOT detection
DATE:    23/11/20 12:29:35 GMT
FROM:    Paul Kuin at MSSL <npkuin@gmail.com>

N.P.M. Kuin (MSSL/UCL) and S. L. Laha (GSFC/UMBC) report

on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 231117A
106 s after the BAT trigger (Laha et al., GCN Circ. 35071).
A source consistent with the XRT position (Beardmore et al.,
GCN Circ. 35074  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              106         1713          392         21.21 +/- 0.27
v                  648         1418           78        >18.8
b                  574         1688           78        >19.3
u                  318          741          265        >19.9

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.071 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB231118A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35135
SUBJECT: 231118A: Swift-UVOT Detection
DATE:    23/11/20 12:42:03 GMT
FROM:    Paul Kuin at MSSL <npkuin@gmail.com>

N.P.M. Kuin (MSSL/UCL) and S. L. Laha (GSFC/UMBC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 231118A
105 s after the BAT trigger (Laha et al., GCN Circ. 35101).
A source consistent with the XRT position (Evans et al., GCN Circ. 35106)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  00:19:19.26 =   4.83024 (deg.)
    Dec (J2000) = -48:02:24.1  = -48.04004 (deg.)
with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence).

Preliminary detections 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              105          255          147         17.28 +/- 0.03
v                 1052         1071           20         16.59 +/- 0.16
b                  573          593           19         17.10 +/- 0.11
u                  318          568          246         16.69 +/- 0.04
w1                1618         1638           19         17.18 +/- 0.24

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.013 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB231117A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35136
SUBJECT: GRB 231117A: CALET Gamma-Ray Burst Monitor detection
DATE:    23/11/20 14:39:59 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 short GRB 231117A (Swift detection: Laha et al., GCN Circ. 35071;
AstroSat CZTI detection: Navaneeth et al.,  GCN Circ. 35072; AGILE 
detection: Cattaneo et al., GCN Circ. 35075; Konus-Wind detection: 
Svinkin et al., GCN Circ. 35079; Glowbug gamma-ray detection: 
Cheung et al., GCN Circ. 35081; AGILE/MCAL analysis: Casentini 
et al., GCN Circ. 35085; GRBAlpha detection: Dafcikova et al., GCN
Circ. 35095; GECAM-C detection: Wang-Chen et al., GCN Circ. 35117)
triggered the CALET Gamma-ray Burst Monitor (CGBM) at 03:03:19.31
UTC on 17 November 2023
(http://cgbm.calet.jp/cgbm_trigger/flight/1384225326/).
The burst signal was seen by all CGBM detectors.

The burst light curve shows a single pulse that starts
at T+0.35 sec, peaks at T+0.68 sec, and ends at T+1.02 sec.
The T90 and T50 durations measured by the SGM data are 0.45 
+/- 0.08 sec and 0.15 +/- 0.02 sec (40-1000 keV), respectively.

The ground-processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1384225326/

The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.


GRB_name: GRB231118B
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35137
SUBJECT: GRB 231118B: CALET Gamma-Ray Burst Monitor detection
DATE:    23/11/20 15:07:18 GMT
FROM:    Yuta Kawakubo at Louisiana State University <kawakubo1@lsu.edu>

S. Nakahira (JAXA), A. Yoshida, T. Sakamoto, S. Sugita (AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U),  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 231118B (Fermi GBM Final Real-time Localization: 
Fermi GBM team, GCN Circ. 35111; BALROG localization: Preis 
et al., GCN Circ 35112; Fermi GBM observation: de Barra et al.,
GCN Circ 35132) triggered the CALET Gamma-ray Burst 
Monitor (CGBM) at 22:34:15.15 UTC on 18 November 2023
(http://cgbm.calet.jp/cgbm_trigger/flight/1384381978/index.html).
The burst signal was seen by HXM1 and SGM detectors.  No real-time 
CGBM GCN notice was distributed about this trigger because
the real-time communication from the ISS was off (loss of signal).

The burst light curve shows a single pulse that starts
at T-0.7 sec, peaks at T+2.8 sec, and ends at T+6.5 sec.
The T90 and T50 durations measured by the SGM data are 5.6 +/- 0.3 sec
and 2.4 +/- 0.1 sec (40-1000 keV), respectively.

The ground-processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1384381978

The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.


GRB_name: GRB231117A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35138
SUBJECT: GRB 231117A: Wendelstein Confirmation of Fading of the Optical Afterglow
DATE:    23/11/20 17:16:21 GMT
FROM:    m.busmann@physik.lmu.de

Malte Busmann (LMU), Daniel Gruen (LMU),  Brendan Oâ€™Connor (CMU), Antonella Palmese (CMU), Lei Hu (CMU), Arno Riffeser (LMU/MPE), Ananya Shankar (LMU) report:

We observed GRB 231117A (Laha et al., GCN 35071; Navaneeth et al., GCN 35072; Beardmore et al., GCN3574; Cattaneo et al., GCN 35075; Svinkin et al., GCN 35079; Cheung et al., GCN 35081, Dafcikova et al., GCN 53095) with the 2m Fraunhofer telescope at Wendelstein Observatory, Germany. Observations were obtained using the 3kk imager in the r, i, and J bands simultaneously. The data were obtained starting at 2023-11-19 18:11:39 UT (~2.6 d after the GRB) under ~2â€ seeing. 

At the location of the optical transient (Yang et al., GCN 35083; Rastinejad et al., GCN 35087; Gompertz et al., GCN 35088; Kumar et al., GCN 35089, Ahumada et al., GCN 35093; Andreoni et al., GCN 35099; Kilpatrick et al., GCN 35102; Chen et al., GCN 35105; Odeh et al., GCN 35118; Takahashi et al., GCN 35133; Schneider et al., GCN 35124) we measure an optical brightness of 

r = 21.1 +/- 0.1 AB mag
i = 21.2 +/- 0.2 AB mag

Image subtraction has not yet been performed and these magnitudes encompass both the transient and host galaxy flux. These measurements are consistent with the archival host galaxy magnitudes, and confirm fading of the optical transient as reported by Fulton et al. (GCN 35121), solidifying the connection to the GRB.

The magnitudes are not corrected for Milky Way extinction and the photometry was calibrated against nearby stars in the PS1 catalog. 

We thank the staff of the Wendelstein Observatory for obtaining these observations.


GRB_name: GRB231117A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35139
SUBJECT: GRB 231117A: LDT Confirmation of Optical Fading
DATE:    23/11/20 17:19:39 GMT
FROM:    Brendan O'Connor at Carnegie Mellon University <boconno2@andrew.cmu.edu>

B. O'Connor (CMU), I. Andreoni (JSI/UMD/NASA-GSFC), G. Srinivasaragavan (UMD), T. Ahumada (Caltech), S. B. Cenko (NASA-GSFC), J. Durbak (UMD), E. Hammerstein (UMD), N. Klingler (UMBC/NASA-GSFC), A. Kutyrev (NASA-GSFC), L. Singer (NASA-GSFC), S. Veilleux (UMD):

We performed additional observations of GRB 231117A (Laha et al., GCN 35071; Navaneeth et al., GCN 35072; Beardmore et al., GCN3574; Cattaneo et al., GCN 35075; Svinkin et al., GCN 35079; Cheung et al., GCN 35081, Dafcikova et al., GCN 53095) with the Large Monolithic Imager (LMI) mounted at the 4-m Lowell Discovery Telescope (LDT) located in Flagstaff, AZ, under program M01 (PI: Andreoni). The observations began on 2023-11-20 02:50:02 UT (~3 d after the GRB) under seeing of ~2.2". We performed observations in the riz bands with 750 s exposure in each band. 

At the location of the optical afterglow (Yang et al., GCN 35083; Rastinejad et al., GCN 35087; Gompertz et al., GCN 35088; Kumar et al., GCN 35089, Ahumada et al., GCN 35093; Andreoni et al., GCN 35099; Kilpatrick et al., GCN 35102; Chen et al., GCN 35105; Odeh et al., GCN 35118; Takahashi et al., GCN 35133; Schneider et al., GCN 35124; Busmann et al., GCN 35138), we clearly detect a source. 

Preliminary photometry (including some contribution from the host) suggests fading by ~0.85 magnitudes in i-band from our previous observations obtained 2.0 days before (Andreoni et al., GCN 35099). Our observations confirm the fading of the optical afterglow candidate, as first reported by Fulton et al. (GCN 35121) and later by Busmann et al. (GCN 35138).

We thank the staff of the Lowell Observatory for their support during the observations. 


GRB_name: GRB231020A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35140
SUBJECT: Konus-Wind detection of GRB 231020A
DATE:    23/11/20 19:43:09 GMT
FROM:    Y. Temiraev at Ioffe Institute <yuri.temiraev@mail.ioffe.ru>

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

The long-duration GRB 231020A
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 34856;
Bala et al., GCN Circ. 34869;
BALROG localization: Preis et al., GCN Circ. 34861;
AstroSat-CZTI detection: Navaneeth et al., GCN Circ. 34880;
GRID detection: Wang and Yang, GCN Circ. 34903;
IPN triangulation: Kozyrev et al., GCN Circ. 34917)
triggered Konus-Wind at T0=68224.628 s UT (18:57:04.628).

The burst light curve shows a single pulse
which starts at ~T0-8.0 s and has a total duration of ~14.2 s.
The emission is seen up to ~10 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB231020_T68224/
Note: 'dip' in the count rate is due
to the GRB source occultation by the s/c structure.

As observed by Konus-Wind, the burst
had a fluence of 3.37(-0.15,+0.17)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+0.992 s,
of 1.09(-0.17,+0.17)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+10.240 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -1.00(-0.12,+0.13),
the high energy photon index beta = -3.11(-0.51,+0.26),
the peak energy Ep = 131(-7,+7) keV
(chi2 = 105/97 dof).

The spectrum near the maximum count rate
(measured from T0 to T0+2.048 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 = -0.85(-0.10,+0.11)
and Ep = 185(-9,+10) keV (chi2 = 91/69 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -3.3
(chi2 = 91/68 dof).

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


GRB_name: GRB231118A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35141
SUBJECT: GRB 231118A: Swift-BAT refined analysis
DATE:    23/11/20 20:35:03 GMT
FROM:    Mike Moss at NASA GSFC <mikejmoss3@gmail.com>

M. J. Moss (GSFC), 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), M. Stamatikos (OSU) (i.e. the Swift-BAT team):
 
Using the data set from T-61 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 231118A (trigger #1197311)
(Laha, et al., GCN Circ. 35101).  The BAT ground-calculated position is
RA, Dec = 4.840, -48.044 deg which is 
   RA(J2000)  =  00h 19m 21.7s 
   Dec(J2000) = -48d 02' 37.5" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 55%.
 
The light curve shows a single pulse with similar rise and fall times.
There is also a dim tail extending 30 seconds after the main pulse.
T90 (15-350 keV) is 37.63 +- 8.89 sec (estimated error including systematics).
 
The time-averaged spectrum from T-6.84 to T+55.21 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.40 +- 0.07.  The fluence in the 15-150 keV band is 3.7 +- 0.2 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T-0.08 sec in the 15-150 keV band
is 9.7 +- 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/1197311/BA/


GRB_name: GRB231117A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35142
SUBJECT: GRB 231117A: AMI-LA radio observations
DATE:    23/11/20 20:44:23 GMT
FROM:    Lauren Rhodes at Oxford <lauren.rhodes@physics.ox.ac.uk>

Lauren Rhodes, Rob Fender (Oxford), Dave Green, Dave Titterington (Cambridge) report:
 
We observed the field of the afterglow candidate GRB 231117A (GCN 35071) with the Arcminute Microkelvin Imager Large-Array (AMI-LA) at 15.5 GHz beginning at UT 15:30:45 on 17-Nov-2023 for a total of 4 hours. The flux standard 3c286 was used to calibrate the bandpass response and flux scale of the AMI-LA and J2232+1143 was used as an interleaved complex gain calibrator.

We do not detect any radio emission at the position of the afterglow candidate as reported in GCN 35083 with a 3-sigma upper limit of 230uJy/beam. 
 
We thank the staff at the Mullard Radio Astronomy Observatory for carrying out these observations and operating the AMI-LA.


GRB_name: GRB231118A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35143
SUBJECT: GRB 231118A: VZLUSAT-2 detection
DATE:    23/11/20 20:47:21 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 231118A (Fermi/GBM detection: GCN 35100; Swift/BAT detection: GCN 35101; AstroSat detection: GCN 35116; Konus/WIND trigger at 2023-11-18 17:16:29.937 UT, INTEGRAL/SPI-ACS peak detection at 2023-11-18 ~17:16:33 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 2023-11-18 17:16:34 UTC. The T90 duration is 8 s and the significance during T90 reaches 5.6 sigma.

The light curve obtained by VZLUSAT-2 is available here:
https://vzlusat2.konkoly.hu/static/share/GRB231118A_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: GRB231118A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35151
SUBJECT: GRB 231118A: GRBAlpha detection
DATE:    23/11/21 14:46:20 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, L. Szakszonova, 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 long-duration GRB 231118A (Fermi/GBM detection: GCN 35100; Swift/BAT detection: GCN 35101; AstroSat detection: GCN 35116; VZLUSAT-2 detection: GCN 35143; Konus/WIND trigger at 2023-11-18 17:16:29.937 UT, INTEGRAL/SPI-ACS peak detection at 2023-11-18 ~17:16:33 UT) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; arXiv:2302.10048).

The detection was confirmed at the peak time 2023-11-18 17:16:33 UTC. The T90 duration measured by GRBAlpha is 4 s and the overall significance during T90 reaches 8.5 sigma in the 120-400 keV band.

The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB231118A_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: GRB231117A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35152
SUBJECT: GRB 231117A: Swift-BAT refined analysis
DATE:    23/11/21 19:58:25 GMT
FROM:    Tyler Parsotan  at NASA GSFC <tyler.parsotan@nasa.gov>

C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa), M. J. Moss (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-60 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 231117A (trigger #1197027)
(Laha, et al., GCN Circ. 35071).  The BAT ground-calculated position is
RA, Dec = 332.404, 13.516 deg which is
   RA(J2000)  =  22h 09m 37.0s
   Dec(J2000) = +13d 30' 58.1"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 83%.

The mask-weighted light curve shows a very strong fast rise exponential decay profile
with potential precursor emission prior to the main pulse.
T90 (15-350 keV) is 0.67 +- 0.07 sec (estimated error including systematics).

The time-averaged spectrum from T-0.42 to T+1.30 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.55 +- 0.04.  The fluence in the 15-150 keV band is 2.3 +- 0.1 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T-0.05 sec in the 15-150 keV band
is 28.9 +- 0.7 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/1197027/BA/

ï»¿


GRB_name: GRB231117A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35153
SUBJECT: GRB 231117A: GTC Near-Infrared Observations
DATE:    23/11/21 21:05:30 GMT
FROM:    Alan M Watson at UNAM <alan@astro.unam.mx>

Alan M. Watson (UNAM), Simone Dichiara (PSU), Eleonora Troja
(UniversitÃ  di Roma Tor Vergata), Brendan Oâ€™Connor (CMU), Rosa L.
Becerra (UNAM), Nathaniel R. Butler (ASU), Nissim Fraija (UNAM),
William Lee (UNAM), OcÃ©lotl LÃ³pez (UNAM), and Margarita Pereyra (UNAM)
report:

We observed the field of GRB 231117A (Laha et al., GCN 35071;
Navaneeth et al., GCN 35072; Beardmore et al., GCN3574; Cattaneo et
al., GCN 35075; Svinkin et al., GCN 35079; Cheung et al., GCN 35081;
Dafcikova et al., GCN 53095; Busman et al. GCN 35138; O'Connor et al.,
GCN 35139) with the EMIR instrument on the GTC telescope from
2023-11-19 19:33 to 19:57 UTC (64.5 to 64.9 hours after the trigger).
We obtained total integrations of 420 in J and 252 in Ks with a seeing
of about 0.8 arcsec.

From our preliminary analysis, the source is detected in all filters
with brightness J = 20.9 +/- 0.1 AB, with an uncertain contribution
from the host galaxy. This value is not corrected for Galactic
extinction.

Further observations are planned.

We thank the staff of the GTC, including Riccardo Scarpa and Antonio
Cabrera, for their help with these observations.


GRB_name: GRB231117A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35154
SUBJECT: GRB 231117A: Swift/UVOT late time observations
DATE:    23/11/21 22:05:33 GMT
FROM:    Paul Kuin at MSSL <npkuin@gmail.com>

N.P.M. Kuin (MSSL/UCL) and S. L. Laha (GSFC/UMBC)
report on behalf of the Swift/UVOT team:

The initial Swift/UVOT observations of the field of GRB 231117A
(Laha et al., GCN Circ. 35071) have been reported by Kuin and
Laha (GCN Circ. 35134) based on the enhanced XRT position (Beardmore
et al. GCN Circ. 35074). A refined position was published by
Yang et al. (GCN Circ. 35083) which we use for the current
circular.

We report here exposures taken over the specified period and summed for
better S/N. We also report here in AB magnitudes (Breeveld et al. 2011,
AIP Conf. Proc. 1358, 373):

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

white              106         1713          392         22.3 +/- 0.5
u                 5863       18,406          917         20.9 +/- 0.2
white           67,725       68,529          675         21.7 +/- 0.2
white          210,209      223,742         4848         22.4 +/- 0.4

Considering that these are AB magnitudes, we can compare the white and u
values to see a likely peak around the time of the u magnitude with a
subsequent decay.

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.071 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB231122A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35156
SUBJECT: GRB 231122A: Fermi GBM Final Real-time Localization
DATE:    23/11/22 12:55:01 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 12:44:22 UT on 22 Nov 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231122A (trigger 722349867.684022 / 231122531).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 108.4, Dec = -5.5 (J2000 degrees, equivalent to J2000 07h 13m, -5d 30'), with a statistical uncertainty of 3.8 degrees.

The angle from the Fermi LAT boresight is 87.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231122531/quicklook/glg_skymap_all_bn231122531.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/bn231122531/quicklook/glg_healpix_all_bn231122531.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231122531/quicklook/glg_lc_medres34_bn231122531.gif


GRB_name: GRB231122B
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35157
SUBJECT: GRB 231122B: GECAM detection
DATE:    23/11/22 16:23:45 GMT
FROM:    Chenwei Wang at IHEP <cwwang@ihep.ac.cn>

Chen-Wei Wang, Shao-Lin Xiong report on behalf of the GECAM team:
GECAM-B was triggered in-flight by a long burst, GRB 231122B 
at 2023-11-22T15:12:41.050 UTC (denoted as T0), 
which was also detected by CALET/GBM (trigger num 1384701074).

According to the realtime alert data of GECAM-B, this burst mainly consists of many pulses
with a duration of about 50 s. The time-averaged spectrum from T0 to T0+17 s 
could be adequately fit by a power law with high energy exponential cutoff function 
with a fluence of about 9.8E-6 erg/cm2 in 20-1000 keV.

Using the automatic on-ground localization pipeline with the realtime alert data, 
GECAM-B localized this burst to the following position (J2000): 
Ra: 106.2 deg 
Dec: -21.3 deg
Err: 1.5 deg (1-sigma, statistical only)

Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor
(GECAM) mission originally consists of two micro-satellites (GECAM-A and GECAM-B)
launched in Dec. 2020. As the third member of GECAM constellation, 
GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. 
GECAM mission is funded by the Chinese Academy of Sciences (CAS).


GRB_name: GRB231122A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35158
SUBJECT: GRB 231122A: GECAM detection
DATE:    23/11/22 16:40:17 GMT
FROM:    Chenwei Wang at IHEP <cwwang@ihep.ac.cn>

Chen-Wei Wang, Shao-Lin Xiong report on behalf of the GECAM team:
GECAM-C was triggered in-flight by a long burst, GRB 231122A 
at 2023-11-22T12:44:26.350 UTC (denoted as T0), 
which was also detected by Fermi/GBM (GCN #35156).

According to the realtime alert data of GECAM-C, this burst mainly consists of many pulses
with a duration of about 50 s. The time-averaged spectrum from T0 to T0+4 s 
could be adequately fit by a power law with high energy exponential cutoff function 
with a fluence of about 6.8E-6 erg/cm2 in 20-1000 keV.

Using the automatic on-ground localization pipeline with the realtime alert data, 
GECAM-C localized this burst to the following position (J2000): 
Ra: 106.1 deg 
Dec: -7.8 deg
Err: 14.2 deg (1-sigma, statistical only)
GECAM location is consistent with that of Fermi/GBM within the error.
We note that this analysis is based on realtime alert data and thus very preliminary.

Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor
(GECAM) mission originally consists of two micro-satellites (GECAM-A and GECAM-B)
launched in Dec. 2020. As the third member of GECAM constellation, 
GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. 
GECAM mission is funded by the Chinese Academy of Sciences (CAS).


GRB_name: GRB231117A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35160
SUBJECT: GRB 231117A: Continued GTC Observations
DATE:    23/11/22 20:56:27 GMT
FROM:    Simone Dichiara at Pennsylvania State University <sbd5667@psu.edu>

Simone Dichiara (PSU), Alan M. Watson (UNAM), Nathaniel R. Butler (ASU), Eleonora Troja (UniversitÃ  di Roma Tor Vergata), Brendan Oâ€™Connor (CMU), Rosa L. Becerra (UNAM), Nissim Fraija (UNAM), William Lee (UNAM), Kin LÃ³pez (UNAM), and Margarita Pereyra (UNAM) report:

We observed the field of GRB 231117A (Laha et al., GCN 35071; Navaneeth et al., GCN 35072; Beardmore et al., GCN3574; Cattaneo et al., GCN 35075; Svinkin et al., GCN 35079; Cheung et al., GCN 35081; Dafcikova et al., GCN 53095; Busman et al. GCN 35138; O'Connor et al., GCN 35139; Watson et al., GCN 35153, Kuin et al., GCN 35154) with the OSIRIS instrument on the GTC telescope from 2023-11-21 20:34 to 21:16 UTC (113.5 to 114.2 hours after the trigger).  We obtained total integrations of 480 s in r and 960 s in z with a seeing of about 0.9 arcsec.

We detect the source in both bands but, even with our good seeing, reliable photometry will require image subtraction. We measure r = 21.8 +/- 0.1 AB, with an uncertain contribution from the host galaxy. This value is not corrected for Galactic extinction.

Further observations are planned.

We thank the staff of the GTC, especially David GarcÃ­a Ãlvarez and Antonio Cabrera, for their help with these observations.


GRB_name: GRB231122B
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35161
SUBJECT: GRB 231122B: Glowbug gamma-ray detection
DATE:    23/11/22 21:21:17 GMT
FROM:    C.C. Cheung at Naval Research Lab <Teddy.Cheung@nrl.navy.mil>

C.C. Cheung, M. Kerr, J. E. Grove, R. Woolf (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge (MSFC), and M.S. Briggs (UAH) report:                                                                                                                                                                                                                                                    

The Glowbug gamma-ray telescope [1,2], operating on the International Space Station, reports the detection of GRB 231122B, which was also detected by GECAM-B (GCN 35157) and CALET/GBM (trigger ID Num 1384701074).

Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2023-11-22 15:12:34.760 with a duration of 41.0 s and a total significance of about 55.7 sigma.  The light curve comprises an initial peak at ~T0+5s followed by a multi-peaked structure with a maximum rate at ~T0+35s.

Using a standard power-law function with an exponential high-energy cutoff [3] to model the emission over this duration results in a photon index dN/dE~E^x of x=0.9 and a cutoff energy ("Epeak") of 308 keV.  The modeled 10-10000 keV fluence is 9.7e-06 erg/cm^2.

Using a standard power-law function with an exponential high-energy cutoff [3] to model the emission over this duration results in a photon index dN/dE~E^x of x=0.2 and a cutoff energy ("Epeak") of 461 keV.  The modeled 10-10000 keV fluence is 5.1e-06 erg/cm^2.

The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.

Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC.  It was launched on 2023 March 15 aboard the Department of Defense Space Test Programâ€™s STP-H9 to the ISS.  The detector comprises 12 large-area (15 cm x 15 cm) CsI:Tl panels covering the surface of a half cube, and two hexagonal (5-cm diameter, 10-cm length) CLLB scintillators, giving it a large field of view (instantaneous FoV ~2/3 sky) over a wide energy band of 50 keV to >2 MeV.

[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959
[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O
[3] Goldstein, A. et al. 2020, ApJ 895, 40, arXiv :1909.03006

Distribution Statement A: Approved for public release.  Distribution is unlimited.


GRB_name: GRB231123A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35162
SUBJECT: GRB 231123A: Fermi GBM Final Real-time Localization
DATE:    23/11/23 02:54:35 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 SHORT GRB

At 02:44:04 UT on 23 Nov 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231123A (trigger 722400249.776634 / 231123114).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 83.8, Dec = -19.6 (J2000 degrees, equivalent to J2000 05h 35m, -19d 36'), with a statistical uncertainty of 9.2 degrees.

The angle from the Fermi LAT boresight is 95.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231123114/quicklook/glg_skymap_all_bn231123114.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/bn231123114/quicklook/glg_healpix_all_bn231123114.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231123114/quicklook/glg_lc_medres34_bn231123114.gif


GRB_name: GRB231117A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35163
SUBJECT: GRB 231117A: Chandra afterglow detection
DATE:    23/11/23 03:12:50 GMT
FROM:    Wen-fai Fong at Northwestern University <wfong@northwestern.edu>

W. Fong, T. Eftekhari, G. Schroeder (Northwestern), A. Rouco Escorial (ESA/ESAC) report:

"The Chandra X-ray Observatory observed the position of the short-duration GRB 231117A (Laha et al., GCN 35071, Navaneeth et al., GCN 35072, Cattaneo et al., GCN 35075, Svinkin et al., GCN 35079, Cheung et al., GCN 35081) starting on 2023 November 21 at 06:22:13 UT. We obtained an ACIS-S observation under Proposal 24400307 (PI: Fong), with an effective exposure time of ~27 ksec, for a mid-time of 4.3 days post-burst. 

The X-ray afterglow is clearly detected at high significance. The source is spatially coincident with the optical (e.g., Yang et al., GCN 35083, Rastinejad et al., GCN 35087, Gompertz et al., GCN 35088) and radio (Rhodes et al., GCN 35097, Schroeder et al., GCN 35114) afterglows at the position:

RA (J2000) = 22:09:33.37
Dec (J2000) = 13:31:20.0

We note that, similar to the reported optical positions, the Chandra source is just outside the 90% confidence region of the latest XRT position. We measure a 0.3-10 keV flux for the Chandra afterglow of FX ~ 2e-13 erg/s/cm^2. We find that the XRT light curve beyond ~300 seconds post-burst can be modeled with a single power-law with FX ~ t^-0.6, and that the Chandra observation is fully consistent with this power law.

We thank the Chandra staff for rapid approval and planning of these observations."


GRB_name: GRB231122B
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35164
SUBJECT: GRB 231122B: Swift/BAT-GUANO detection of a long burst outside the coded FOV 
DATE:    23/11/23 03:43:29 GMT
FROM:    Samuele Ronchini at PSU <sjs8171@psu.edu>

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

Swift/BAT did not localize GRB 231122B onboard (T0: 2023-11-22T15:12:41.050 UTC, GECAM GCN 35157, CALET trigger 1384701074, Glowbug GCN 35161) 

The GECAM 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), performed on the temporal window [T0-20 s, T0+20 s], detects the burst with a sqrt(TS) of 41.8 in a 16.384 s analysis time bin, starting at T0 + 16.38 s.

NITRATES results are consistent with a burst coming from outside the FOV, with DeltaLLHOut of -29.5 and are consistent with GECAM localization (GCN 35157).

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: GRB231122B
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35165
SUBJECT: GRB 231122B: CALET Gamma-Ray Burst Monitor detection
DATE:    23/11/23 03:58:18 GMT
FROM:    Yuta Kawakubo at Louisiana State University <kawakubo1@lsu.edu>

Y. Asaoka (ICRR), A. Yoshida, T. Sakamoto, S. Sugita (AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA),
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 231122B (GECAM detection: Wang et al., GCN
Circ. 35157; Glowbug gamma-ray detection: Cheung et al., GCN
Circ. 35161; Swift/BAT-GUANO detection: Ronchini et al., GCN
Circ. 35164) triggered the CALET Gamma-ray Burst Monitor (CGBM)
at 15:12:38.15 UTC on 22 November 2023
(http://cgbm.calet.jp/cgbm_trigger/flight/1384701074/).
The burst signal was seen by all CGBM detectors.

The burst light curve shows a multi-peaked structure that starts
at T+2.5 sec, peaks at T+3.3 sec, and ends at T+41.7 sec.
The T90 and T50 durations measured by the SGM data are 34.0 +/- 1.0 sec
and 22.6 +/- 1.3 sec (40-1000 keV), respectively.

The ground-processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1384701074/index.html

The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.


GRB_name: GRB231122B
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35166
SUBJECT: GRB 231122B: AstroSat CZTI detection
DATE:    23/11/23 06:38:32 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 bright long-duration GRB 231122B which was also detected by GECAM-B (Wang et al., GCN Circ. 35157), Glowbug (Cheung et al., GCN Circ. 35161), Swift-BAT GUANO (Ronchini et al., GCN Circ. 35164), and CALET (Asaoka et al., GCN Circ. 35165).

The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2023-11-22 15:13:12.50 UTC. The measured peak count rate associated with the burst is 456 (+42, -40) counts/s above the background in the combined data of three quadrants (out of four), with a total of 7475 (+364, -396) counts. The local mean background count rate was 240 (+2, -3) counts/s. Using cumulative rates, we measure a T90 of 34.1 (+1.7, -1.2) s. We caution that there is a 0.3 s readout dead time in CZTI data just before the burst. Hence, the T90 can be as large as 35.8 s for this GRB, with a lower limit of 32.9 s as estimated above by cumulative rates. In the preliminary analysis, we find 685 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 2023-11-22 15:13:11.68 UTC. The measured peak count rate associated with the burst is 538 (+68, -48) counts/s above the background in the combined data of all quadrants, with a total of 7112 (+819, -804) counts. The local mean background count rate was 1220 (+5, -6) counts/s. We measure a T90 of 32 (+2, -1) 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: GRB231118A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35167
SUBJECT: GRB 231118A: REM optical afterglow detection
DATE:    23/11/23 13:57:31 GMT
FROM:    Paolo D'Avanzo at INAF-OAB <pda.davanzo@gmail.com>

R. Brivio, M. Ferro, P. D'Avanzo, D. Fugazza, S. Covino (INAF-OAB) on behalf of the REM team, report:

We observed the field of GRB 231118A (Fermi GBM Team., GCN 35100; Laha et al., GCN 35101) with the REM 60cm robotic telescope located at the ESO Observatory of La Silla (Chile). The observations were carried out in the g, r, i, z, J, H and K bands, starting on 2023 Nov 19 at 00:16:39 UT (i.e. about 7.00 hours after the GBM and Swift trigger) and lasted for about 1 hour.

The optical afterglow (Dutton et al., GCN 35103, Strausbaugh et al., GCN 35110, Shrestha et al., GCN 35113, de Wet et al., GCN 35126, Takahashi et al., GCN 35133), is detected in r, i bands coadded frames (t_exp = 20 min) . From preliminary photometry, we derive the following magnitudes and limits:

r = 19.66 +/- 0.08 (AB)
i = 19.19 +/- 0.11 (AB; calibrated against the the APASS catalogue)
at a mid time of t-t0 ~ 7.68 hours after the GRB trigger.

H > 17.7 (Vega; calibrated against the 2MASS catalogue) 
at a mid time of t-t0 ~ 7.44 hours after the GRB trigger.


GRB_name: GRB231123B
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35170
SUBJECT: GRB 231123B: Fermi GBM Final Real-time Localization
DATE:    23/11/23 19:35:41 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 19:25:21 UT on 23 Nov 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231123B (trigger 722460326.50637 / 231123809).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 160.4, Dec = -68.9 (J2000 degrees, equivalent to J2000 10h 41m, -68d 54'), with a statistical uncertainty of 6.1 degrees.

The angle from the Fermi LAT boresight is 104.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231123809/quicklook/glg_skymap_all_bn231123809.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/bn231123809/quicklook/glg_healpix_all_bn231123809.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231123809/quicklook/glg_lc_medres34_bn231123809.gif


GRB_name: GRB231123C
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35171
SUBJECT: GRB 231123C: Fermi GBM Final Real-time Localization
DATE:    23/11/23 20:08:55 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 SHORT GRB

At 19:58:25 UT on 23 Nov 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231123C (trigger 722462310.383788 / 231123832).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 162.3, Dec = 45.9 (J2000 degrees, equivalent to J2000 10h 49m, 45d 53'), with a statistical uncertainty of 22.2 degrees.

The angle from the Fermi LAT boresight is 107.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231123832/quicklook/glg_skymap_all_bn231123832.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/bn231123832/quicklook/glg_healpix_all_bn231123832.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231123832/quicklook/glg_lc_medres34_bn231123832.gif


GRB_name: GRB231117A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35172
SUBJECT: GRB 231117A: Mondy optical observations
DATE:    23/11/23 23:07:40 GMT
FROM:    Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>

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

We observed the field of GRB 231117A (Laha et al., GCN 35071; Navaneeth et al., GCN 35072; Beardmore et al., GCN3574; Cattaneo et al., GCN 35075; Svinkin et al., GCN 35079; Cheung et al., GCN 35081; Dafcikova et al., GCN 53095; Busman et al. GCN 35138; O'Connor et al., GCN 35139; Watson et al., GCN 35153, Kuin et al., GCN 35154; Dichiara  et al., GCN 35160; Fong et al., GCN 35163) with AZT-33IK telescope of Mondy observatory  in  R-filter on 2023-11-17, 2023-11-18 and 2023-11-20. Using image subtraction and the image on 2023-11-20 as a template we obtained preliminary photometry of the optical transient

Date       UT start  t-T0     Exp.   Filter   OT     Err.  
                   (mid, days)  (s)
2023-11-17 11:45:33  0.38349  30x120 R        21.00  0.16   
2023-11-18 12:09:46  1.41142  46x120 R        21.59  0.16  

The photometry is based on nearby USNO-B1.0 R2 stars. The index of power law (t-T0)^-alpha between  the two epochs is alpha = 0.8 (+0.13 -0.2).
However, photometry may be biased due to the template contamination by a still decaying optical transient, so we caution against using this index for any physical assessments.


GRB_name: GRB231123A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35173
SUBJECT: GRB 231123A: AstroSat CZTI detection
DATE:    23/11/24 07:55:13 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 faint GRB 231123A which was also detected by Fermi-GBM (Fermi GBM team, GCN Circ. 35162).

We see a faint detection in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2023-11-23 02:44:04.5 UTC. The measured peak count rate associated with the burst is 173 (+82, -43) counts/s above the background in the combined data of three quadrants (out of four), with a total of 203 (+97, -93) counts. The local mean background count rate was 272 (+4, -6) counts/s. Using cumulative rates, we measure a T90 of 3.5 (+1.5, -2.3) s.

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: GRB231124A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35174
SUBJECT: GRB 231124A: Fermi GBM Final Real-time Localization
DATE:    23/11/24 08:48:40 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 08:38:11 UT on 24 Nov 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231124A (trigger 722507896.88707 / 231124360).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 237.5, Dec = 10.9 (J2000 degrees, equivalent to J2000 15h 50m, 10d 54'), with a statistical uncertainty of 2.1 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/bn231124360/quicklook/glg_skymap_all_bn231124360.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/bn231124360/quicklook/glg_healpix_all_bn231124360.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231124360/quicklook/glg_lc_medres34_bn231124360.gif


GRB_name: GRB231115A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35175
SUBJECT: GRB 231115A: XMM-Newton observation
DATE:    23/11/24 12:25:39 GMT
FROM:    Sandro Mereghetti at IASF-Milano/INAF <sandro.mereghetti@inaf.it>

M. Rigoselli, D. P. Pacholski, S. Mereghetti, R. Salvaterra (INAF, IASF-Milano) and S. Campana (INAF, OAB) on behalf of a larger collaboration report:

XMM-Newton carried out a target of opportunity observation  of GRB 231115A (Mereghetti et al., GCN 35037; Fermi GBM Team, GCN 35035) which is likely a magnetar giant flare in the M82 galaxy (Dâ€™Avanzo et al., GCN 35036; Burns, GCN 35038) and was also detected by Glowbug (Cheung et al., GCN 35045), Insight-HXMT (Xue et al., GCN 35060), Konus-Wind (Frederiks et al. GCN 35062) and Swift/BAT (Ronchini et al., GCN 35065).

The burst location was observed with the EPIC instrument on 2023-11-16 from 08:27 UT  to 21:19 UT (To+16.8 hr to To+29.7 hr).  A large fraction of the ~46 ks long observation was affected by high background, resulting in cleaned exposure times of 8.4 ks for the pn camera and 19.0 and 23.6 ks for the MOS1 and MOS2 cameras, respectively.

Comparison of  images in various energy ranges with those of the  EPIC observations of M82 in 2021 and 2022, does not reveal any new source inside the INTEGRAL IBAS error circle  (2 arcmin radius, Mereghetti et al., GCN 35037). 

For about 50% of the error region, we derived a 3 sigma count rate upper limit of 0.004 pn cts/s in the 2-10 keV energy range. For an absorbed power law spectrum with photon index 2 and N_H=6.5E20 cm-2 this corresponds to about 3E-14 erg/cm2/s (2-10 keV). 

Diffuse X-ray emission from the central part of M82 affects the error region, resulting in limits higher than 0.01 pn cts/s (2-10 keV) in less than 20% of the error region.

The lack of detection of an X-ray afterglow associated to GRB 231115A in the XMM-Newton observation 16.8 hours after the trigger provides further evidence that the burst is likely a magnetar giant flare in the M82 galaxy.


GRB_name: GRB231124A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35176
SUBJECT: GRB 231124A: CALET Gamma-Ray Burst Monitor detection
DATE:    23/11/24 14:01:20 GMT
FROM:    Yuta Kawakubo at Louisiana State University <kawakubo1@lsu.edu>

S. Torii (Waseda U), A. Yoshida, T. Sakamoto, S. Sugita (AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA),
Y. Asaoka (ICRR), 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 231124A (Fermi GBM Final Real-time Localization: 
Fermi GBM team, GCN Circ. 35174) triggered the CALET Gamma-ray
Burst Monitor (CGBM) at 08:38:12.68 UTC on 24 November 2023
(http://cgbm.calet.jp/cgbm_trigger/flight/1384850206/).
The burst signal was seen by all CGBM detectors.

The burst light curve shows a multi-peaked structure that starts
at T-0.2 sec, peaks at T+10.9 sec, and ends at T+17.9 sec.
The T90 and T50 durations measured by the SGM data are 
16.7 +/- 1.0 sec and 7.1 +/- 1.1 sec (40-1000 keV), respectively.

The ground-processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1384850206/

The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.


GRB_name: GRB231123C
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35179
SUBJECT: GRB 231123C: Swift/BAT-GUANO detection of a short burst likely outside the coded FOV
DATE:    23/11/24 18:30:16 GMT
FROM:    Aaron Tohuvavohu at University of Toronto <aaron.tohu@gmail.com>

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

Swift/BAT did not localize GRB 231123C onboard (T0: 2023-11-23T19:58:25 UTC, Fermi GBM Trig 722462310, GCN 35171). 

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 12.8 in a 0.6 s analysis time bin, starting at T0 - 0.08 s.

NITRATES results, independently, are ambiguous with respect to whether this burst originates from in or outside the BAT coded FOV, with a DeltaLLHOut of 7.6.

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: GRB230506B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35180
SUBJECT: GRB230506B: VIRT optical upper limit
DATE:    23/11/24 20:33:20 GMT
FROM:    Priya Gokuldass at ERAU <gokuldap@my.erau.edu>

K. Noonan (UVI), P. Gokuldass (ERAU), N. Orange (OrangeWave Innovative Science, LLC), D. Morris (NASA), K. Smith (UVI), R. Querrard (UVI), T. Lombardi (Eckerd College)

We observed the field of GRB230506B (Dichiara et al. GCN 33727) with the 0.5m Virgin Island Robotic Telescope (VIRT) at the University of the Virgin Islands' Etelman Observatory on 05-07-2023 starting at 05:20:40.065 (T+16.33 hrs). We performed a series of exposures in R filter with a total exposure of 3860 s. The weather conditions were clear during the hours of observation with an average airmass of ~2.6.

We do not detect an uncatalogued source within the Swift-XRT error region and report the following 3-sigma upper limit: 

T_mid     ||Exposure ||Filter ||Limit 
T+17 hrs ||3860s     ||R        ||>20.1 

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: GRB230506C
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35181
SUBJECT: GRB230506C: VIRT optical upper limit
DATE:    23/11/24 20:35:39 GMT
FROM:    Priya Gokuldass at ERAU <gokuldap@my.erau.edu>

Kiwaneeâ€™ Smith (UVI), P. Gokuldass (ERAU), N. Orange (OrangeWave Innovative Science, LLC), D. Morris (NASA), Kiâ€™Vanteâ€™ Smith (UVI), K. Noonan (UVI), R. Querrard (UVI), T. Lombardi (Eckerd College)

We observed the field of GRB230506C (Tohuvavohu et al. GCN 33731) with the 0.5m Virgin Island Robotic Telescope (VIRT) at the University of the Virgin Islands' Etelman Observatory on 05-07-2023 starting at 00:17:36.395 (T+7.07 hrs). We performed a series of exposures in R filter with a total exposure of 3810 s. The weather conditions were clear during the hours of observation with an average airmass of ~1.55.

We do not detect the source identified by others (Pankov et al., GCN 33734; Jelinek  et al., GCN 33735; Adami et al., GCN 33741; Moskvitin et al., GCN 33748) and report the following 3-sigma upper limit: 

T_mid       ||Exposure ||Filter ||Limit 
T+7.3 hrs ||3810s         ||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: GRB230728A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35182
SUBJECT: GRB230728A: VIRT optical upper limit
DATE:    23/11/24 20:38:00 GMT
FROM:    Priya Gokuldass at ERAU <gokuldap@my.erau.edu>

Kiwanee' Smith (UVI), P. Gokuldass (ERAU), N. Orange (OrangeWave Innovative Science, LLC), D. Morris (NASA), K. Noonan (UVI), R. Querrard (UVI), T. Lombardi (Eckerd College), Dylon Smith (UVI)

We observed the field of GRB230728A (Salvaggio et al., GCN 34282; Evans et al., GCN 34286) with the 0.5m Virgin Island Robotic Telescope (VIRT) at the University of the Virgin Islands' Etelman Observatory on 07-28-2023 starting at 04:22:27.816 (T+1.3 hrs). We performed a series of exposures in R filter with a total exposure of 1560s. The weather conditions were clear during the hours of observation with an average airmass of ~1.2. 

We do not detect any source within the enhanced XRT position (Evans et al., GCNC 34286). This non-detection is consistent with the upper limits reported by MASTER (Lipunov et al. GCNC 34281), NOT (Xu et al. GCNC 34285), UVOT (Oates et al. GCNC 34288), LCOGT (Strausbaugh et al. GCNC 34289) and BOOTES-1 (Hu et al. GCNC 34291). We report the following 3-sigma upper limit: 

T_mid        ||Exposure ||Filter ||Limit 
T+ 1.5 hrs ||1560s         ||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: GRB231124A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35183
SUBJECT: GRB 231124A: Glowbug gamma-ray detection
DATE:    23/11/24 22:31:50 GMT
FROM:    C.C. Cheung at Naval Research Lab <Teddy.Cheung@nrl.navy.mil>

C.C. Cheung, M. Kerr, J. E. Grove, R. Woolf (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge (MSFC), and M.S. Briggs (UAH) report:                                                                                                                                                                                                                                                   
 
The Glowbug gamma-ray telescope [1,2], operating on the International Space Station, reports the detection of GRB 231124A, which was also detected by Fermi/GBM and CALET (GCN 35174, 35176).
 
Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2023-11-24 08:38:09.832 with a duration of 21.0 s and a total significance of about 44.7 sigma.  The light curve comprises a multi-peaked structure with maximum rates at ~T0+13s and ~T0+19s.
 
Using a standard power-law function with an exponential high-energy cutoff [3] to model the emission over this duration results in a photon index dN/dE~E^x of x=0.9 and a cutoff energy ("Epeak") of 254 keV.  The modeled 10-10000 keV fluence is 4.9e-06 erg/cm^2.
 
The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.
 
Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC.  It was launched on 2023 March 15 aboard the Department of Defense Space Test Programâ€™s STP-H9 to the ISS.  The detector comprises 12 large-area (15 cm x 15 cm) CsI:Tl panels covering the surface of a half cube, and two hexagonal (5-cm diameter, 10-cm length) CLLB scintillators, giving it a large field of view (instantaneous FoV ~2/3 sky) over a wide energy band of 50 keV to >2 MeV.
 
[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959
[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O
[3] Goldstein, A. et al. 2020, ApJ 895, 40, arXiv :1909.03006
 
Distribution Statement A: Approved for public release.  Distribution is unlimited.


GRB_name: GRB231123C
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35184
SUBJECT: GRB 231123C (short): Glowbug gamma-ray detection
DATE:    23/11/24 23:38:43 GMT
FROM:    C.C. Cheung at Naval Research Lab <Teddy.Cheung@nrl.navy.mil>

C.C. Cheung, M. Kerr, J. E. Grove, R. Woolf (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge (MSFC), and M.S. Briggs (UAH) report:                                                                                                                                                                                                                                                   
 
The Glowbug gamma-ray telescope [1,2], operating on the International Space Station, reports the detection of GRB 231123C, which was also detected by Fermi/GBM and Swift/BAT-GUANO (GCN 35171, 35179).
 
Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2023-11-23 19:58:24.304 with a duration of 0.256 s and a total significance of about 11.5 sigma.  The light curve comprises a single peak.
 
Using a standard power-law function with an exponential high-energy cutoff [3] to model the emission over this duration results in a photon index dN/dE~E^x of x=1.5 and a cutoff energy ("Epeak") of 322 keV.  The modeled 10-10000 keV fluence is 2.4e-07 erg/cm^2.
 
The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.
 
Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC.  It was launched on 2023 March 15 aboard the Department of Defense Space Test Programâ€™s STP-H9 to the ISS.  The detector comprises 12 large-area (15 cm x 15 cm) CsI:Tl panels covering the surface of a half cube, and two hexagonal (5-cm diameter, 10-cm length) CLLB scintillators, giving it a large field of view (instantaneous FoV ~2/3 sky) over a wide energy band of 50 keV to >2 MeV.
 
[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959
[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O
[3] Goldstein, A. et al. 2020, ApJ 895, 40, arXiv :1909.03006
 
Distribution Statement A: Approved for public release.  Distribution is unlimited.


GRB_name: GRB231123C
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35187
SUBJECT: GRB 231123C: Insight-HXMT/HE detection
DATE:    23/11/25 12:47:01 GMT
FROM:    yqzhang_cl@163.com

Y.Q Zhang, S. L. Xiong, X. B. Li and C. K. Li
report on behalf of the Insight-HXMT team:

At 2023-11-23T19:58:25.38 (T0), Insight-HXMT/HE detected
GRB 231123C (trigger ID: HEB231123832) in a routine search of the data,
which was also observed by Fermi/GBM (Fermi GBM Team, GCN 35171),
Swift/BAT(James DeLaunay et al., GCN 35179) and 
Glowbug (C. C. Cheung et al., GCN 35184). 

The Insight-HXMT/HE light curve mainly consists of single
pulse with a duration (T90) of 0.41 s measured from T0-0.24 s.
The 1-ms peak rate, measured from T0-0.09 s, is 1741 cnts/sec.
The total counts from this burst is  291 counts.
URL_LC: http://twiki.ihep.ac.cn/pub/HXMT/GRBList/HEB231123832_lc.jpg

All measurements above are made with the CsI detectors operating in the
regular mode with the energy range of about 80-800 keV (deposited energy).
Only gamma-rays with energy greater than about 200 keV can penetrate
the spacecraft and leave signals in the CsI detectors installed inside
the telescope.

Insight-HXMT is the first Chinese space X-ray telescope, which was
funded jointly by the China National Space Administration (CNSA) and
the Chinese Academy of Sciences (CAS).
More information about it could be found at:
http://www.hxmt.org.


GRB_name: GRB231126A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35188
SUBJECT: GRB 231126A: Fermi GBM Final Real-time Localization
DATE:    23/11/26 01:23:00 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 01:12:22 UT on 26 Nov 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231126A (trigger 722653947.93232 / 231126050).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 277.4, Dec = 25.6 (J2000 degrees, equivalent to J2000 18h 29m, 25d 36'), with a statistical uncertainty of 6.7 degrees.

The angle from the Fermi LAT boresight is 91.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231126050/quicklook/glg_skymap_all_bn231126050.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/bn231126050/quicklook/glg_healpix_all_bn231126050.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231126050/quicklook/glg_lc_medres34_bn231126050.gif


GRB_name: GRB231111A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35189
SUBJECT: GRB 231111A: Optical follow-up observations at Terskol, AbAO, Maidanak, Mondy, Assy
DATE:    23/11/26 08:22:44 GMT
FROM:    Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>

N. Pankov (HSE, IKI), A. Pozanenko (IKI), I. Sokolov (INASAN), R. Inasaridze (AbAO), O. Burhonov (UBAI), E. Klunko (ISTP),  V. Kim (FAI),  Sh. Ehgamberdiev (UBAI), S. Belkin (IKI) report on behalf of GRB-IKI-FuN collaboration:

We observed the field of GRB 231111A (Melandri et al., GCN 34981; Zhang et al, GCN 34990) at with several telescopes,  Zeiss-2000 telesope (Terskol),  AS-32 (Abastumani), AZT-22 (Maidanak), AZT-33IK (Mondy) and AZT-20 (Assy).The observations started at Terskol on 2023-11-11 17:37:54, i.e. 3.359712 hr since Swift trigger. The optical source is detected only in the stacked image of 12*300 sec from Maidanak Observatory in the R-filter,  while in other cases we obtained the upper limits. The results are in consistent with observations previously reported by other teams and us (Melandri et al., GCN 34981; Jiang et al, GCN 34982; Lipunov et al, GCN 34983; Kumar et al, GCN 34984; Sun et al, GCN 34985; Pankov et al, GCN 34994; Ruocco et al, GCN 34997; Wang et al, GCN 35000; Li et al, GCN 35001; Sun et al, GCN 35002; Moretti et al, GCN 35003; Komesh et al, GCN 35004; D'Avanzo et al, GCN 35007; Thoene et al, GCN 35009; Jiang et al, GCN 35012; Sun et al, GCN 35014). Preliminary photome!
 try is following:

Date       UT start t-T0    Exp.  Filter OT Err. UL(3sigma)  Telescope

2023-11-11 17:37:54 0.13998  2*120 R n/d  n/d   19.5 Zeiss-2000 
2023-11-12 14:47:53 1.02157 86*60  R n/d  n/d   20.5 AS-32  
2023-11-12 19:25:37 1.21583 12*300 R 21.06 0.08 22.7 AZT-22  
2023-11-13 11:14:51 1.87399 50*120 R n/d  n/d   20.7 AZT-33IK  
2023-11-13 15:09:27 2.07092 200*30 r n/d  n/d   23.0 AZT-20  

The photometry is based on nearby stars from USNO-B1.0 and PS1 catalogs.


GRB_name: GRB231125A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35190
SUBJECT: GRB 231125A: AstroSat CZTI detection of a short burst
DATE:    23/11/26 10:14:19 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-duration GRB 231125A. We also inspected  INTEGRAL/SPI-ACS data, and see a detection there.

The source was clearly detected in the 20-200 keV energy range. The light curve peaks at 2023-11-25 17:47:20.75 UTC. The measured peak count rate associated with the burst is 1641.9 (+219.7, -187.4) counts/s above the background in the combined data of three quadrants (out of four), with a total of 901 (+67, -66) counts. The local mean background count rate was 255.6 (+3.7, -6.9) counts/s. Using cumulative rates, we measure a T90 of 1.09 (+0.31, -0.23) 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 2023-11-25 17:47:20.72 UTC. The measured peak count rate is 1315.6 (+87.4, -93.6) counts/s above the background in the combined Veto data of all quadrants, with a total of 2706 (+219, -253) counts. The local mean background count rate was 1618.4 (+11.8, -11.9) counts/s. Due to the intrinsic 1 s binning of veto data, we cannot reliably estimate a T90 from it.

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: GRB231124A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35193
SUBJECT: GRB 231124A: GRBAlpha detection
DATE:    23/11/26 16:56:42 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, L. Szakszonova, 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 long-duration GRB 231124A (Fermi/GBM detection: GCN 35174; CALET/CGBM detection: GCN 35176; Glowbug detection: GCN 35183; INTEGRAL/SPI-ACS peak detection at 2023-11-24 ~08:38:25 UT) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; arXiv:2302.10048).

The detection was confirmed at the peak time 2023-11-24 08:38:17 UTC. The T90 duration measured by GRBAlpha is 20 s and the overall significance during T90 reaches 12 sigma.

The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB231124A_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: GRB231123B
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35195
SUBJECT:  GRB 231123B: Swift/BAT-GUANO detection of a burst outside the coded FOV
DATE:    23/11/26 19:43:19 GMT
FROM:    Jimmy DeLaunay at University of Alabama  <delauj2@gmail.com>

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

Swift/BAT did not localize GRB 231123B onboard (T0: 2023-11-23T19:25:21.51 UTC, Fermi trig 722460326) 

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 90 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), performed on the temporal window [T0-20 s, T0+20 s], detects the burst with a sqrt(TS) of 8.8 in a 8.192 s analysis time bin, starting at T0 - 4.096 s. 

NITRATES results are consistent with a burst coming from outside the FOV, with DeltaLLHOut of 0.4.

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: GRB231125A
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35196
SUBJECT: GRB 231125A (short): Glowbug gamma-ray detection
DATE:    23/11/27 01:19:23 GMT
FROM:    C.C. Cheung at Naval Research Lab <Teddy.Cheung@nrl.navy.mil>

C.C. Cheung, M. Kerr, J. E. Grove, R. Woolf (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge (MSFC), and M.S. Briggs (UAH) report:                                                                                                                                                                                                                                                    

The Glowbug gamma-ray telescope [1,2], operating on the International Space Station, reports the detection of GRB 231125A, which was also detected by Astrosat/CZTI and INTEGRAL/SPI-ACS (GCN 35190).

Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2023-11-25 17:47:19.344 with a duration of 1.15 s and a total significance of about 194 sigma.  The light curve comprises a single peak.

Using a standard power-law function with an exponential high-energy cutoff [3] to model the emission over this duration results in a photon index dN/dE~E^x of x=0.7 and a cutoff energy ("Epeak") of 296 keV.  The modeled 10-10000 keV fluence is 6.1e-06 erg/cm^2.

The best-fit localization is RA, Decl. (J2000) = 109.7 deg, -30.6 deg with a radius of 2.6 deg (95% confidence), with a highly uncertain systematic uncertainty.

The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.

Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC.  It was launched on 2023 March 15 aboard the Department of Defense Space Test Programâ€™s STP-H9 to the ISS.  The detector comprises 12 large-area (15 cm x 15 cm) CsI:Tl panels covering the surface of a half cube, and two hexagonal (5-cm diameter, 10-cm length) CLLB scintillators, giving it a large field of view (instantaneous FoV ~2/3 sky) over a wide energy band of 50 keV to >2 MeV.

[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959
[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O
[3] Goldstein, A. et al. 2020, ApJ 895, 40, arXiv :1909.03006

Distribution Statement A: Approved for public release.  Distribution is unlimited.


GRB_name: GRB231127A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35197
SUBJECT: GRB 231127A: AstroSat CZTI detection
DATE:    23/11/27 11:28:01 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-duration GRB 231127A which was also detected by CALET (Trigger Num. 1385097164).

The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2023-11-27 05:14:21.75 UTC. The measured peak count rate associated with the burst is 433 (+159, -60) counts/s above the background in the combined data of all quadrants, with a total of 571 (+157, -130) counts. The local mean background count rate was 325 (+7, -11) counts/s. Using cumulative rates, we measure a T90 of 3.0 (+1.4, -0.8) 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 2023-11-27 05:14:21.69 UTC. The measured peak count rate associated with the burst is 822 (+78, -76) counts/s above the background in the combined data of all quadrants, with a total of 2145 (+310, -342) counts. The local mean background count rate was 1452 (+11, -12) counts/s. We measure a T90 of 5 (+2, -3) s from the cumulative Veto light curve. We note that this T90 measurement has higher uncertainty due to the intrinsic 1 s binning of Veto data. 

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: GRB231125A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35198
SUBJECT: GRB 231125A: CALET Gamma-Ray Burst Monitor detection
DATE:    23/11/27 12:41:07 GMT
FROM:    Yuta Kawakubo at Louisiana State University <kawakubo1@lsu.edu>

Y. Akaike (Waseda U), A. Yoshida, T. Sakamoto, S. Sugita (AGU), 
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA),
Y. Asaoka (ICRR), S. Torii, 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 GRB 231125A (AstroSat CZTI detection: Waratkar et al.,  
GCN Circ 35190; Glowbug gamma-ray detection: Cheung et al.,
GCN Circ 35196) triggered the CALET Gamma-ray Burst Monitor 
(CGBM) at 17:47:20.53 UTC on 25 November 2023
(http://cgbm.calet.jp/cgbm_trigger/flight/1384969551/index.html).
The burst signal was seen by all CGBM detectors.  No real-time 
CGBM GCN notice was distributed about this trigger because
the real-time communication from the ISS was off (loss of signal).

The burst light curve shows a single pulse that starts
at T-0.19 sec, peaks at T+0.41 sec, and ends at T+1.60 sec.
The T90 and T50 durations measured by the SGM data are 
1.17 +/- 0.13 sec and 0.40 +/- 0.04 sec (40-1000 keV), respectively.

The ground-processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1384969551/

The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.


GRB_name: GRB231125A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35199
SUBJECT: GRB 231125A: GRBAlpha detection
DATE:    23/11/27 13:02:50 GMT
FROM:    Jakub Ripa <ripa.jakub@gmail.com>

J. Ripa, M. Dafcikova (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, L. Szakszonova, 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 231125A (AstroSat/CZTI detection: GCN 35190; Glowbug detection: GCN 35196; INTEGRAL/SPI-ACS peak detection at 2023-11-25 ~17:47:21 UT) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; arXiv:2302.10048).

The detection was confirmed at the peak time 2023-11-25 17:47:20.8 UTC. The T90 duration measured by GRBAlpha is 2 s and the overall significance during T90 reaches 12 sigma.

The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB231125A_GCN_GRBAlpha.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: GRB231127A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35200
SUBJECT: GRB 231127A: CALET Gamma-Ray Burst Monitor detection
DATE:    23/11/27 15:08:54 GMT
FROM:    Yuta Kawakubo at Louisiana State University <kawakubo1@lsu.edu>

GRB 231127A: CALET Gamma-Ray Burst Monitor detection

K. Kobayashi (Waseda U), A. Yoshida, T. Sakamoto, S. Sugita (AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA),
Y. Asaoka (ICRR), S. Torii, Y. Akaike (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 231127A (AstroSat CZTI detection: Navaneeth et al.,
GCN Circ 35197) triggered the CALET Gamma-ray Burst Monitor 
(CGBM) at 05:14:16.39 UTC on 27 November 2023
(http://cgbm.calet.jp/cgbm_trigger/flight/1385097164/index.html).
The burst signal was seen by all CGBM detectors.

The burst light curve shows a single pulse that starts
at T+2.9 sec, peaks at T+5.4 sec, and ends at T+8.1 sec.
The T90 and T50 durations measured by the SGM data are 
4.0 +/- 0.4 sec and 1.4 +/- 0.1 sec (40-1000 keV), respectively.

The ground-processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1385097164/

The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.


GRB_name: GRB231117A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35201
SUBJECT: GRB 231117A: MeerKAT 1.3GHz detection
DATE:    23/11/27 16:10:58 GMT
FROM:    Lauren Rhodes at Oxford <lauren.rhodes@physics.ox.ac.uk>

L. Rhodes (Oxford), G. Schroeder (Northwestern), G. Anderson (Curtin), W. Fong (Northwestern), S. Chastain (UNM), A. Gulati (USyd), A. van der Horst(GWU), C. Kilpatrick (Northwestern), N. Klinger (NASA/GSFC), T. Laskar (Utah), J. K. Leung (UofT/HUJI), A. Nugent (Northwestern), J. Rastinejad (Northwestern), S. D. Ryder (Macquarie) on behalf of a larger collaboration.

We observed GRB 231117A (GCN 35071) with the MeerKAT radio telescope at 1.3GHz for a total of 2 hours starting on 26 November 2023 at 12:47 UTC. The observations used J1939-6342 and J2232+1143 as flux and phase calibrators, respectively. Using the SARAO SDP image we find an unresolved source at the position of the afterglow candidate (GCN 35083) with a flux density of ~100uJy/beam. The rms noise in the field is 7uJy/beam. We note that the measured flux density may have a substantial contribution from the host galaxy reported in GCN 35083 but said contribution cannot be quantified until the afterglow has faded. 

We thank the staff at the South African Radio Astronomy Observatory for scheduling these observations.


GRB_name: GRB231123B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35204
SUBJECT: GRB 231123B: Fermi GBM Observation
DATE:    23/11/27 23:30:13 GMT
FROM:    Sarah Dalessi at UAH <sd0104@uah.edu>

S. Dalessi (UAH), S. Lesage (UAH) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 19:25:21.51 UT on 23 November 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 231123B (trigger 722460326/231123809).
which was also detected by Swift/BAT-GUANO (J. DeLaunay et al. 2023, GCN 35195).
The Fermi Final Localization was reported in GCN 35170.

The angle from the Fermi LAT boresight is 104 degrees.

The GBM light curve single peak with a duration (T90)
of about 77 s (50-300 keV). The time-averaged spectrum
from T0+0.003 to T0+76.802 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -1.2 +/- 0.2 and the cutoff energy,
parameterized as Epeak, is 160 +/- 38 keV.

The event fluence (10-1000 keV) in this time interval is
(5.9 +/- 0.7)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+4.5 s in the 10-1000 keV band is 1.9 +/- 0.3 ph/s/cm^2.

The spectrum is also well fit a Band function with Epeak = 115 +/- 44 keV,
alpha = -1.05 +/- 0.28, and beta = -2.16 +/- 0.31.

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: GRB231123C
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35205
SUBJECT: GRB 231123C: Fermi GBM Observation
DATE:    23/11/28 00:38:45 GMT
FROM:    Sarah Dalessi at UAH <sd0104@uah.edu>

S. Dalessi (UAH), S. Lesage (UAH) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 19:58:25.38 UT on 23 November 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 231123C (trigger 722462310/231123832).
which was also detected by Swift/BAT-GUANO (J. DeLaunay et al. 2023, GCN 35179).
The Fermi Final Localization was reported in GCN 35171.

The angle from the Fermi LAT boresight is 90 degrees.

The GBM light curve single peak with a duration (T90)
of about 0.4 s (50-300 keV). The time-averaged spectrum
from T0-0.1 to T0+0.4 s is best fit by
a Power law function with alpha = -1.29 +/- 0.06.

The event fluence (10-1000 keV) in this time interval is
(3.3 +/- 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 5 +/- 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: GRB231129A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35208
SUBJECT: GRB 231129A: Swift detection of a burst
DATE:    23/11/29 05:19:12 GMT
FROM:    Aaron Tohuvavohu at University of Toronto <aaron.tohu@gmail.com>


J.D. Gropp (PSU), N. J. Klingler (GSFC/UMBC/CRESSTII),
D. M. Palmer (LANL), M. H. Siegel (PSU) and A. Tohuvavohu (U Toronto)
report on behalf of the Neil Gehrels Swift Observatory Team:

At 05:05:59 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 231129A (trigger=1199764).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 317.536, +41.544 which is 
   RA(J2000) = 21h 10m 09s
   Dec(J2000) = +41d 32' 37"
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 120 sec.  The peak count rate
was ~3700 counts/sec (15-350 keV), at ~90 sec after the trigger. 

The XRT began observing the field at 05:07:51.1 UT, 112.0 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 317.54581, 41.52062 which
is equivalent to:
   RA(J2000)  = 21h 10m 10.99s
   Dec(J2000) = +41d 31' 14.2"
with an uncertainty of 4.0 arcseconds (radius, 90% containment). This
location is 88 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. No
spectrum from the promptly downlinked event data is yet available to
determine the column density. 

The initial flux in the 0.1 s image was 3.05e-08 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 120 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. 
Results from the list of sources generated on-board are not available at this
time. No correction has been made for the large, but uncertain, extinction
expected. 

Burst Advocate for this burst is J.D. Gropp (jdg44 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: GRB231129A
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35209
SUBJECT: GRB 231129A: INTEGRAL detection of a long GRB
DATE:    23/11/29 08:37:29 GMT
FROM:    Sandro Mereghetti at IASF-Milano/INAF <sandro.mereghetti@inaf.it>

S.Mereghetti (INAF, IASF-Milano), D.Gotz (CEA, Saclay), C.Ferrigno, E.Bozzo, V.Savchenko (ISDC, Versoix), L.Ducci (IAAT, Germany and ISDC, Versoix) and J.Borkowski (CAMK, Torun) report:

a gamma ray burst lasting about 150 s has been detected by IBAS in the  IBIS/ISGRI data at 05:05:59  UT of November 25, 2023.  The burst has also been detected by Swift (Gropp et al. GCN 35208)

The refined coordinates (J2000) are:
R.A.=  317.53411 deg
DEC.=  +41.51942 deg
with an uncertainty of 1.5  arcmin (90% c.l.).

The burst had a peak flux of about 0.5 ph/cm2/s (20-200 keV, 1-s integration time) and a fluence in the same energy range of about 6e-7 erg/cmq.

A plot of the light curve will  be posted at 
http://ibas.iasf-milano.inaf.it/IBAS_Results.html


GRB_name: GRB231129A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35210
SUBJECT: GRB 231129A: GECAM-C detection of a long burst 
DATE:    23/11/29 09:29:57 GMT
FROM:    wenlongzhang2018@163.com

Wen-Long Zhang, Shao-Lin Xiong report on behalf of the GECAM team:

GECAM-C was triggered in-flight by a long burst, GRB 231129A, at 2023-11-29T05:06:01.850 UTC (T0), which was also observed by Swift/BAT (GCN #35208) and INTEGRAL (GCN #35209). 

According to the realtime alert data, the GECAM-C light curve shows roughly two peaks with a total duration of ~80 sec (15-1050 keV). 

The time-averaged spectrum of GECAM-C realtime data from about T0 to T0+4 s could be
adequately fit by a cut-off power-law with a fluence about 1.84E-6 erg/cm^2 in 20-1000 keV. 

GECAM location is consistent with that of Swift/BAT and INTEGRAL within the error.
We note that these results are based on realtime alert data and thus very preliminary. Refined analysis will be reported later.

Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor(GECAM) mission originally consists of two microsatellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS).


GRB_name: GRB231129B
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35214
SUBJECT: GRB 231129B: MAXI/GSC detection
DATE:    23/11/29 15:23:40 GMT
FROM:    Motoko Serino at Aoyama Gakuin U. <serino@phys.aoyama.ac.jp>

M. Kurihara (JAXA), H. Negoro (Nihon U.), M. Serino (AGU), W. Iwakiri (Chiba U.),
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, E.Goto (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, M. Kurihara (JAXA), 
Y. Ueda, K. Setoguchi, T. Yoshitake, Y. Nakatani, Y. Okada (Kyoto U.), 
M. Yamauchi, Y. Hagiwara, Y. Umeki, Y. Otsuki (Miyazaki U.), 
K. Yamaoka (Nagoya U.),
Y. Kawakubo (LSU),
M. Sugizaki (NAOC),
report on behalf of the MAXI team:

The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at 14:03:05 UT on 29 November 2023.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (285.662 deg, 40.278 deg) = (19 02 38, +40 16 40) (J2000)
with a statistical 90% C.L. elliptical error region
with long and short radii of 0.39 deg and 0.26 deg, respectively.
The roll angle of long axis from the north direction is 75.0 deg counterclockwise.
Without assumptions on the source constancy, we obtain a rectangular error
box for the transient source with the following corners:
(283.889, 39.749) deg = (18 55 33, +39 44 56) (J2000)
(284.232, 39.302) deg = (18 56 55, +39 18 07) (J2000)
(286.730, 40.399) deg = (19 06 55, +40 23 56) (J2000)
(286.398, 40.853) deg = (19 05 35, +40 51 10) (J2000)
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).

The X-ray flux averaged over the scan was 141 +- 32 mCrab
(4.0-10.0keV, 1 sigma error).
There was no significant excess flux in the previous transit at 12:30 UT
with an upper limit of 20 mCrab.


GRB_name: GRB231129B
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35215
SUBJECT: GRB 231129B: Tiled Swift observations
DATE:    23/11/29 17:28:07 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
MAXI GRB 231129B. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00116

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 MAXI 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: GRB231129C
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35217
SUBJECT: GRB 231129C: Fermi GBM Final Real-time Localization
DATE:    23/11/29 19:39:45 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 19:10:18 UT on 29 Nov 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231129C (trigger 722977823.114938 / 231129799).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 2.0, Dec = -81.5 (J2000 degrees, equivalent to J2000 00h 08m, -81d 30'), with a statistical uncertainty of 1.0 degrees.

The angle from the Fermi LAT boresight is 50.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231129799/quicklook/glg_skymap_all_bn231129799.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/bn231129799/quicklook/glg_healpix_all_bn231129799.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231129799/quicklook/glg_lc_medres34_bn231129799.gif


GRB_name: GRB231129A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35218
SUBJECT: GRB 231129A: Swift-XRT refined Analysis
DATE:    23/11/29 20:35:31 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

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

We have analysed 7.0 ks of XRT data for GRB 231129A, from 115 s to 43.8
ks after the  BAT trigger. The data comprise 174 s in Windowed Timing
(WT) mode with the remainder in Photon Counting (PC) mode. The refined
XRT position is RA, Dec = 317.5437, +41.5206 which is equivalent to:

RA (J2000): 21 10 10.49
Dec(J2000): +41 31 14.2

with an uncertainty of 3.5 arcsec (radius, 90% confidence).

The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=4.86 (+/-0.21). At T+165 s  the decay
steepens to an alpha of 6.44 (+0.28, -0.24) before breaking again at
T+308 s to a final decay with index alpha=0.83 (+0.05, -0.06).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.83 (+/-0.07). The
best-fitting absorption column is  1.09 (+/-0.08) x 10^22 cm^-2, in
excess of the Galactic value of 5.9 x 10^21 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.18 (+0.31, -0.29)
and a best-fitting absorption column of 1.6 (+/-0.4) x 10^22 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 5.0 x 10^-11 (1.2 x 10^-10) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.6 (+/-0.4) x 10^22 cm^-2
Galactic foreground: 5.9 x 10^21 cm^-2
Excess significance: 4.5 sigma
Photon index:      2.18 (+0.31, -0.29)

If the light curve continues to decay with a power-law decay index of
0.83, the count rate at T+24 hours will be 0.014 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.2 x
10^-13 (1.8 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/01199764.

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


GRB_name: GRB231129A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35220
SUBJECT: GRB 231129A: Enhanced Swift-XRT position
DATE:    23/11/29 20:56:33 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 2261 s of XRT Photon Counting mode data and 6 UVOT
images for GRB 231129A, 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 = 317.54381, +41.52204 which is equivalent
to:

RA (J2000): 21h 10m 10.51s
Dec (J2000): +41d 31' 19.4"

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: GRB231129C
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35221
SUBJECT: GRB 231129C: Fermi GBM detection of a very bright burst
DATE:    23/11/29 21:13:24 GMT
FROM:    Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov>

V. Sharma (NASA-GSFC/UMBC) and O. Roberts (NASA-MSFC/USRA) report on behalf of the Fermi GBM Team:

"At 19:10:18.11 UT on 29 November 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231129C (trigger 722977823/231129799).

The GBM light curve consists of a very bright pulse, with a duration of about 15 seconds. This event, a likely, long GRB, is very bright and follow-up across all wavelengths is encouraged.

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 2.04, Dec = -81.53 (J2000 degrees, equivalent to J2000 00h 08m, -81d 32'), 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 50 degrees.

A full science circular is forthcoming. 

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231129799/quicklook/glg_skymap_all_bn231129799.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/bn231129799/quicklook/glg_healpix_all_bn231129799.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231129799/quicklook/glg_lc_medres34_bn231129799.gif."


GRB_name: GRB231129C
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35222
SUBJECT: GRB 231129C: BALROG localization (Fermi Trigger  / GRB 231129799)
DATE:    23/11/29 22:08:45 GMT
FROM:    Jochen Greiner at MPE <jcgrog@mpe.mpg.de>

T. Preis, B. Biltzinger, J. Burgess & J. Greiner (all MPE Garching) report:

The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
 at 19:10:18 on 29 Nov. 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) = 7.8+/-1.7 deg
Decl.(2000.0) = -81.3+/-0.3 deg
We estimate an additional systematic error of 2 deg.

Further details are available at:
https://grb.mpe.mpg.de/grb/GRB231129799/

The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB231129799/healpix

The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB231129799/json

                        


GRB_name: GRB231129C
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35223
SUBJECT: GRB 231129C: MAXI/GSC detection
DATE:    23/11/29 22:19:44 GMT
FROM:    kurihara@ac.jaxa.jp

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, M. Serino, S. Sugita, H. Hiramatsu, H. Nishikawa, A. Yoshida (AGU),
Y. Tsuboi, S. Urabe, S. Nawa, N. Nemoto, E.Goto (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, Y. Okada (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 2023/11/29 19:10:18 UT.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (11.910 deg, -81.636 deg) = (00 47 38, -81 38 09) (J2000)
with a statistical 90% C.L. elliptical error region
with long and short radii of 0.09 deg and 0.07 deg, respectively.
The roll angle of long axis from the north direction is 90.0 deg counterclockwise.
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 1355 +- 82 mCrab
(4.0-10.0keV, 1 sigma error).
Without assumptions on the source constancy, we obtain a rectangular error
box for the transient source with the following corners:
(R.A., Dec) = (12.351, -81.744) deg = (00 49 24, -81 44 38) (J2000)
(R.A., Dec) = (11.353, -81.663) deg = (00 45 24, -81 39 46) (J2000)
(R.A., Dec) = (12.374, -81.394) deg = (00 49 29, -81 23 38) (J2000)
(R.A., Dec) = (13.350, -81.472) deg = (00 53 23, -81 28 19) (J2000)
There was no significant excess flux in the previous transit at 17:37 UT
 with an upper limit of 20 mCrab for each.


GRB_name: GRB231127A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35224
SUBJECT: GRB 231127A: GRBAlpha detection
DATE:    23/11/29 22:31:48 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, L. Szakszonova, 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 long-duration GRB 231127A (AstroSat detection: GCN 35197; CALET/CGBM detection: GCN 35200; Konus/Wind trigger at 2023-11-27 05:14:24.085 UT; INTEGRAL/SPI-ACS peak detection at 2023-11-27 ~05:14:20 UT) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; arXiv:2302.10048).

The detection was confirmed at the peak time 2023-11-27 05:14:21 UTC. The T90 duration measured by GRBAlpha is 6 s and the overall significance during T90 reaches 14 sigma.

The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB231127A_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: GRB231129C
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35225
SUBJECT: GRB 231129C: Tiled Swift observations
DATE:    23/11/30 00:33:31 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/GBM GRB 231129C. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00117

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/GBM 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: GRB231129C
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35226
SUBJECT: GRB 231129C: iTelescope likely optical afterglow AT 2023yph discovery
DATE:    23/11/30 04:57:40 GMT
FROM:    Filipp Dmitrievich Romanov at Amateur astronomer <filipp.romanov.27.04.1997@gmail.com>

I observed the field of GRB 231129C (Fermi GBM Team, GCN Circ. 35217)
near the MAXI (GCN Circ. 35223) sky region using remote telescope T72
(0.51-m f/6.8 Corrected Dall-Kirkham + CCD) of iTelescope.Net in Deep
Sky Chile at Rio Hurtado Valley, Chile. 9 images (with exposures 300
seconds, BINx1) were obtained with Ic filter with midtime 02:27 UT. I
detected an uncataloged source with position 00 49 17.780 -81 29 45.83
and measured its brightness near +18 mag. Magnitude was not corrected
for Galactic extinction. I am guessing this is an optical afterglow of
GRB 231129C. Now it is AT 2023yph
https://www.wis-tns.org/object/2023yph
F. D. Romanov (AAVSO).


GRB_name: GRB231129C
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35227
SUBJECT: GRB 231129C: Fermi GBM Observation of a very bright GRB
DATE:    23/11/30 04:57:42 GMT
FROM:    Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov>

V. Sharma (NASA-GSFC/UMBC), C. Fletcher (USRA) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team:

"At 19:10:18.11 UT on 29 November 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231129C (trigger 722977823/231129799), which was also detected by MAXI/GSC (Y. Kawakubo et al. 2023, GCN 35223). The Fermi GBM Final Real-time Localization is reported (GCN 35221, GCN 35217).

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

The GBM light curve shows a very bright, single pulse starting from about T0+0 s to T0+15 s. The calculated duration (T90) is about 6 s (50-300 keV). The time-averaged spectrum from T0+0 s to T0+7 s can be fit by a Band function with Epeak = 215 +/- 2 keV, alpha = -0.11 +/- 0.01, and beta = -2.79 +/- 0.03. 

The event fluence (10-1000 keV) in this time interval is (8.41 +/- 0.04)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 102 +/- 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: GRB231129C
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35228
SUBJECT: GRB 231129C: CALET Gamma-Ray Burst Monitor detection
DATE:    23/11/30 06:11:11 GMT
FROM:    Yuta Kawakubo at Louisiana State University <kawakubo1@lsu.edu>

Y. Shimizu (Kanagawa U), A. Yoshida, T. Sakamoto, S. Sugita (AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA),
Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (Waseda U),
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 231129C (Fermi GBM Final Real-time Localization: Fermi GBM team,
GCN Circ. 35217; Fermi GBM detection: Sharma at al., GCN Circ. 35221; BALROG 
localization: Preis et al., GCN Circ 35222; MAXI/GSC detection: Kawakubo et al., 
GCN Circ. 35223) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 
19:10:15.03 UTC on 29 November 2023
(http://cgbm.calet.jp/cgbm_trigger/flight/1385320118/index.html).
The burst signal was seen by all CGBM detectors.

The burst light curve shows a single pulse that starts
at T+3.1 sec, peaks at T+4.7 sec, and ends at T+8.9 sec.
The T90 and T50 durations measured by the SGM data are 4.7 +/- 0.4 sec
and 2.2 +/- 0.2 sec (40-1000 keV), respectively.

The ground-processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1385320118/index.html

The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.


GRB_name: GRB231129C
Detection_method: retraction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35229
SUBJECT: GRB 231129C: iTelescope OT retraction
DATE:    23/11/30 07:25:40 GMT
FROM:    Filipp Dmitrievich Romanov at Amateur astronomer <filipp.romanov.27.04.1997@gmail.com>

Retraction of GCN #35226. I did not have access to a computer to check
in time that this object was a star with a high proper motion. I
initially compared my images with archival images from the DSS Plate
Finder, but now I have determined that AT 2023yph is a star
#4631003097698452224 from the Gaia DR3.


GRB_name: GRB231129C
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35230
SUBJECT: GRB 231129C: AstroSat CZTI detection
DATE:    23/11/30 09:47:31 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 an extremely bright long-duration GRB 231129C which was also detected by Fermi-GBM (Fermi GBM team, GCN Circ. 35217), MAXI/GSC (Kawakubo et al., GCN Circ. 35223), and CALET (Shimizu et al., GCN Circ. 35228).

The source was clearly detected in the CZT detectors in the 20-200 keV energy range. Based on the orientation of the CZTI, the burst saturated two quadrants (A, B out of four). We report two versions of our analysis of CZT data: one from two unsaturated quadrants (C, D), and the other for all four quadrants by including unsaturated data segments from A, B. 

For the two unsaturated quadrants C and D, the light curve peaks at 2023-11-29 19:10:18 UTC. The measured peak count rate associated with the burst is 1189 (+237, -8) counts/s above the background in the combined CD data, with a total of 3838 (+150, -144) counts. The local mean background count rate was 155.1 (+3.7, -5.9) counts/s. Using cumulative rates, we measure a T90 of 5.1 (+0.2, -0.2) s in these two quadrants. 

Using unsaturated data segments from all four quadrants, we report that burst duration was 6.7 (+0.2, -0.2) s. We also report a minimum peak count rate of 4164.2 (+328.9, -329.3) counts/s at a local mean background count rate of 334.8 (+6.7, -7.4) count/s, with a total of at least 8061 (+195, -236) counts. In the preliminary analysis, we find 1362 Compton events associated with this event in all four quadrants.

It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2023-11-29 19:10:18.69 UTC. The measured peak count rate is 4408 (+125, -126) counts/s above the background in the combined Veto data of all quadrants, with a total of 18860 (+406, - 410) counts. The local mean background count rate was 1511.3 (+6.5, -7.7) counts/s. We measure a T90 of 5.5 (+0.2, -0.2) 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: GRB231129C
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35231
SUBJECT: GRB 231129C: GECAM-B detection of a bright burst
DATE:    23/11/30 10:03:59 GMT
FROM:    yqzhang_cl@163.com

GRB 231129C: GECAM-B detection of a bright burst

Chao Zheng, Shaolin Xiong, report on behalf of the GECAM team:

GECAM-B was triggered in-flight by a likely long burst, GRB 231129C,
at 2023-11-29T19:10:18.200 UTC, which was also observed by 
Fermi/GBM (Fermi/GBM team, GCN 35217 & 35227) and MAXI/GSC 
(Y. Kawakubo et al., GCN 35223) and CALET (Y. Shimizu et al., GCN 35228)
and AstroSat (G. Waratkar et al., GCN 35230).

According to the realtime alert data of GECAM-B, this burst mainly consists 
of a bright pulse with a total duration (T90) of about ~15 sec (20-1000 keV).

The GECAM light curve could be found here: 
http://twiki.ihep.ac.cn/pub/HXMT/GRBList/GRB231129C_LC.png

GECAM location is consistent with that of MAXI/GSC within the error.
We note that these results are based on realtime alert data and thus very preliminary. 
Refined analysis will be reported later.

Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor
(GECAM) mission originally consists of two microsatellites (GECAM-A and GECAM-B)
launched in Dec. 2020. As the third member of GECAM constellation, 
GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. 
GECAM mission is funded by the Chinese Academy of Sciences (CAS).


GRB_name: GRB231129A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35232
SUBJECT: GRB 231129A: optical upper limit in Mondy observatory
DATE:    23/11/30 11:05:26 GMT
FROM:    Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>

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

We observed the field of Swift GRB 231129A (Gropp et al., GCN 35208; Mereghetti et al., GCN 35209; Zhang et al., GCN 35210) with AZT-33IK telescope of Mondy observatory in R-filter on 2023-11-29 starting (UT) 10:43:30. We do not detect any optical objects within the enhanced Swift-XRT error box (Goad et al., GCN 35220). Preliminary photometry of a stacked image is following

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

2023-11-29  10:43:30   0.25730       33x120 R      n/d  n/d  23.1

The photometry is based on nearby USNO-B1.0 stars.
USNO-B1.0
RA DEC R2
21:10:16.6747200 +41:33:09.000000 17.36
21:10:16.0548000 +41:32:49.822800 18.82


GRB_name: GRB231129A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35233
SUBJECT: GRB 231129A: Swift/UVOT Upper Limits
DATE:    23/11/30 13:17:20 GMT
FROM:    Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL) and J. D. Gropp (PSU) report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 231129A (Gropp et al., GCN circ. 35208; Mereghetti et al., GCN circ. 35209; Zhang et al., GCN circ. 35210) 120 s after the BAT trigger (Gropp et al., GCN Circ. 35208).
No optical afterglow consistent with the XRT position (Goad et al., GCN Circ. 35220) 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           120          270          147         >20.5
white              120         4158          344         >20.8
v                 4369         4568          197         >18.9
b                 3753         3953          197         >19.4
u                  333         5122          275         >19.9
w1                4780         4980          197         >18.8
m2                4574         4773          197         >18.9
w2                4164         4364          197         >19.2

The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 1.164 in the direction of the burst (Schlegel et al. 1998).


GRB_name: GRB231129C
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35234
SUBJECT: GRB 231129C: Swift-XRT observations
DATE:    23/11/30 13:59:14 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

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

Swift-XRT has performed follow-up observations of the
Fermi/GBM-detected burst GRB 231129C in a series of observations tiled
on the sky. The total exposure time is 1.5 ks, distributed over 4
tiles; the maximum exposure at a single sky location was 633 s. The
data were collected between T0+19.3 ks and T0+35.4 ks, and are entirely
in Photon Counting (PC) mode. 

One uncatalogued X-ray source has been detected, it is below the RASS
limit and shows no definitive signs of fading. Therefore, at the
present time we cannot confirm this as the afterglow. Details of this
source are given below:

Source 2:
  RA (J2000):  11.1769  =  00:44:42.45
  Dec (J2000): -81.9936  =  -81:59:37.0
  Error: 9.5 arcsec (radius, 90% conf.)
  Count-rate: 0.0208 [+0.0113, -0.0084] ct s^-1   
  Distance: 1341 arcsec from Fermi/GBM position.
  Flux: (8.6 [+4.7, -3.5])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

A catalogued source was 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_GRB00117.

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


GRB_name: GRB231129C
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35235
SUBJECT: GRB 231129C: Glowbug gamma-ray detection
DATE:    23/11/30 14:25:52 GMT
FROM:    C.C. Cheung at Naval Research Lab <Teddy.Cheung@nrl.navy.mil>

C.C. Cheung, M. Kerr, J. E. Grove, R. Woolf (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge (MSFC), and M.S. Briggs (UAH) report:                                                                                                                                                                                                                                                    

The Glowbug gamma-ray telescope [1,2], operating on the International Space Station, reports the detection of GRB 231129C, which was also detected by Fermi/GBM, MAXI/GSC, CALET, AstroSat/CZTI, and GECAM-B (GCN 35217, 35221, 35222, 35223, 35227, 35228, 35230, 35231).

Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2023-11-29 19:10:16.184 with a duration of 8.19 s and a total significance of about 116 sigma.  The light curve comprises an initial triple-peaked structure from T0 to ~T0+4s, followed by fading emission.

Using a standard power-law function with an exponential high-energy cutoff [3] to model the emission over this duration results in a photon index dN/dE~E^x of x=1.4 and a cutoff energy ("Epeak") of 349 keV.  The modeled 10-10000 keV fluence is 1.5e-05 erg/cm^2.

The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.

Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC.  It was launched on 2023 March 15 aboard the Department of Defense Space Test Programâ€™s STP-H9 to the ISS.  The detector comprises 12 large-area (15 cm x 15 cm) CsI:Tl panels covering the surface of a half cube, and two hexagonal (5-cm diameter, 10-cm length) CLLB scintillators, giving it a large field of view (instantaneous FoV ~2/3 sky) over a wide energy band of 50 keV to >2 MeV.

[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959
[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O
[3] Goldstein, A. et al. 2020, ApJ 895, 40, arXiv :1909.03006

Distribution Statement A: Approved for public release.  Distribution is unlimited.


GRB_name: GRB231129C
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35236
SUBJECT: GRB 231129C: GRBAlpha detection
DATE:    23/11/30 14:26:15 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, L. Szakszonova, 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 bright long-duration GRB 231129C (Fermi/GBM detection: GCN 35217; MAXI/GSC detection: GCN 35223; CALET/CGBM detection: GCN 35228; AstroSat detection: GCN 35230; GECAM-B detection: GCN 35231; INTEGRAL/SPI-ACS peak detection at 2023-11-29 ~19:10:19 UT) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; arXiv:2302.10048).

The detection was confirmed at the peak time 2023-11-29 19:10:19 UTC. The T90 duration measured by GRBAlpha is 6 s and the overall significance during T90 reaches 93 sigma.

The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB231129C_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: GRB231129A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35237
SUBJECT: GRB 231129A: JinShan optical upper limit
DATE:    23/11/30 16:47:03 GMT
FROM:    Dong Xu at NAOC/CAS <dxu@nao.cas.cn>

X. Liu, Z.P. Zhu, J. An, S.Q. Jiang, S.Y. Fu, T.H. Lu, D. Xu (NAOC), S.W Luo, M.M. Yang, Z. K. Feng, L.F. Huo (XJTS) report on behalf of a large collaboration:

We observed the field of GRB 231129A detected by Swift (J.D. Gropp, GCN 35208), INTEGRAL (S.Mereghetti et al., GCN 35209), and GECAM-C (Wen-Long Zhang et al., GCN 35210), using the  100cm C telescope (100C) located at Altay, Xinjiang, China. Observations started at 12:13:36.29 UT on 2023-11-29, i.e., 7.13 hr after the Swift/BAT trigger, and 30*120s frames are obtained in the Sloan-r band.

No credible optical transient is detected in our stacked images within the refined Swift/XRT error region (Burrows et al., GCN 35218), down to a 3-sigma upper limit of r > 21.6 mag, calibrated with nearby PanSTARRS stars and not corrected for Galactic extinction.


GRB_name: GRB231129C
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35238
SUBJECT: GRB 231129C: Fermi-LAT detection
DATE:    23/11/30 18:39:08 GMT
FROM:    Nicola Omodei at Stanford University <nicola.omodei@gmail.com>

M. Arimoto (Kanazawa University), N. Omodei (Stanford University), D. Kocevski (NASA/MSFC) report on behalf of the Fermi-LAT Collaboration:

On November 29, 2023 Fermi-LAT detected high-energy emission from GRB 231129C, which was also detected by Fermi-GBM (trigger 722977823 / 231129799, GCN 35221),  MAXI-GSC (GCN 35223), CALET (GCN 35228), AstroSat (GCN 35230),  GECAM-B (GCN 3523), Glowbug (GCN 35235), and GRBAlpha (GCN 35236).
The best LAT on-ground location is found to be R.A., Dec. = 9.1, -81.9 (degrees, J2000) with an error radius of 0.7 deg (90% containment, statistical error only). 
This was 49 deg from the LAT boresight at the time of the GBM trigger:
T0 = 19:10:18.11 UT.
The data from the Fermi-LAT show a significant increase in the event rate after the GBM trigger that is spatially correlated with the GBM emission with high significance. The photon flux above 100 MeV in the time interval 0-200 s after the GBM trigger is (3.2 +/- 0.9)E-4 ph/cm2/s.
The estimated photon index above 100 MeV is -2.4 +/- 0.4. The highest-energy photon is a 0.7 GeV event which is observed 4 seconds after the GBM trigger.

The Fermi-LAT point of contact for this burst is Feraol Fana Dirirsa (ffdirirsa@gmail.com)
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: GRB231129A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35239
SUBJECT: GRB 231129A: BOOTES-5/JGT optical upper limit
DATE:    23/11/30 18:49:02 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, S.-Y. Wu, 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 231129A by Swift (Gropp et al. GCNC 35208), INTEGRAL (Mereghetti et al. GCNC 35209) and GECAM-C (Zhang et al. GCNC 35210), the BOOTES-5/JGT 0.6m robotic telescope at Observatorio Astronomico Nacional in San Pedro Martir (Mexico) automatically observed the GRB location starting on Nov. 29, 05:07 UT (~ 61 s after trigger). No new optical source is detected on the co-added image (15 x 10 s, clear filter) within the Swift/XRT error region (Goad et al. GCNC 35220) down to 19.9 mag, which is consistent with reports from MASTER (Lipunov et al. GCNC 35212), Mondy (Belkin et al. GCNC 35232), UVOT (Breeveld et al. GCNC 35233) and JinShan (Liu et al. GCNC 35237).

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


GRB_name: GRB231129C
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35240
SUBJECT: GRB 231129C: MASTER OT detection
DATE:    23/11/30 19:18:20 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>

G.Antipov, V.Lipunov, E.Gorbovskoy (Lomonosov MSU), D.Buckley (SAAO),
D.Svinkin (Ioffe Institute, Konus-Wind),
Ya.Kechin, K.Zhirkov, A.Kuznetsov, D.Vlasenko, P.Balanutsa, Yu.Tselik, N.Tiurina, I.Gorbunov, V.Vladimirov,
D.Zimnukhov, V.Senik, A.Yudin,A.Chasovnikov, D.Cheryasov, A.Sosnovskij (Lomonosov  MSU,SAI,PhysicsDepartment),
O.A. Gres, N.M. Budnev (Irkutsk State University, API),
C.Francile.  F. Podesta, R.Podesta (Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra(The Instituto de Astrofisica de Canarias),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity)

MASTER Global robotic net (http://observ.pereplet.ru Lipunov et al.,2010,Advances in Astronomy,2010,30L)
started GECAM-B (Ttrigger=2023-11-29 19:10:18.2, Tnotice_socket=2023-11-29  19:11:45.56 Zheng et al. GCN 35231) and
 Fermi very bright GRB 231129C (Ttrigger=2023-11-29 19:10:18.11, Tnotice_socket=2023-11-29 19:19:40.72 Sharma et al. GCN 35227,
GCN 35238, also  MAXI-GSC (GCN 35223), CALET (GCN 35228), AstroSat (GCN 35230))

55 sec after notice time and 90 sec after trigger time at 2023-11-29 19:11:48 UT (Lipunov et al. GCN 35216)
by MASTER-SAAO.

There is OT source at R.A.,Dec(2000)=00:44:37.97 -81:59:48.75 +-4" with  m_OT~17.6 at maximum (unfiltered) at first images with decay inside Swift XRT error-box (Evans et al. GCN 35225, Gropp  et al. GCN 35234)

Reduction will be continued.


GRB_name: GRB231129A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35241
SUBJECT: GRB 231129A: Swift-BAT refined analysis
DATE:    23/11/30 22:41:45 GMT
FROM:    Sibasish Laha at GSFC <sibasish.laha@nasa.gov>

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

Using the data set from T-61 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 231129A (trigger #1199764)
(Gropp et al., GCN Circ. 35208).  The BAT ground-calculated position is
RA, Dec = 317.541, 41.530 deg which is
   RA(J2000)  =  21h 10m 09.8s
   Dec(J2000) = +41d 31' 48.3"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 46%.

The BAT  light curve shows a complex structure with a duration of ~ 130 sec.
T90 (15-350 keV) is 105.46 +- 1.83 sec (estimated error including systematics).

The time-averaged spectrum from T-1.75 to T+118.97 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 1.35 +- 0.17,
and Epeak of 83.7 +- 14.6 keV (chi squared 51.44 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 1.3 +- 0.0 x 10^-05 erg/cm2
and the 1-sec peak flux measured from T+88.71 sec in the 15-150 keV band is
4.8 +- 0.3 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.78 +- 0.04 (chi squared 70.95 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/1199764/BA/


GRB_name: GRB231129C
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35242
SUBJECT: GRB 231129C: Swift/BAT-GUANO localization of a burst outside the coded FOV
DATE:    23/12/01 03:52:27 GMT
FROM:    Jimmy DeLaunay at Penn State <delauj2@gmail.com>

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

Swift/BAT did not localize GRB 231129C onboard (T0: 2023-11-29T19:10:15.02 UTC, CALET trig 1385320118 / GCN 35223 Fermi GBM trig 722460326 / GCN 35221, GECAM trig 238 / GCN 35231, MAXI-GSC GCN 35223, AstroSat GCN 35230, Glowbug GCN 35235, GRBAlpha GCN 35236, Fermi LAT GCN 35238) 

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 90 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), performed on the temporal window [T0-20 s, T0+20 s], detects the burst with a sqrt(TS) of 92.6 in a 4.096 s analysis time bin, starting at T0 + 3.072 s. 

NITRATES results are consistent with a burst coming from outside the FOV, with DeltaLLHOut of -477.

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

A preliminary localization of this GRB was performed, finding a best fit position of 
RA, Dec = 301.3, -80.4 deg
With a roughly circular 90% error radius of 11.1 deg

Calibration of systematics for localizations outside the coded field of view is not yet complete.

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: GRB231129A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35243
SUBJECT: GRB 231129A : MITSuME Akeno optical upper limits
DATE:    23/12/01 09:27:23 GMT
FROM:    Narikazu Higuchi at Tokyo Tech <higuchi@hp.phys.titech.ac.jp>

N. Higuchi, I. Takahashi, M. Sasada, M. Niwano, S. Sato, S. Hayatsu, H. Takei,  H. Seki, Y. Yatsu and N. Kawai  (Tokyo Tech) report on behalf of the MITSuME collaboration:

We observed the field of GRB 231129A (Gropp et al. GCN 35208 and Mereghetti et al. GCN 35209) with the optical three-color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50-cm telescope Akeno. 

The observation started at 2023-11-29 08:01:47 UT (2.93 hours after the Swift/BAT and INTEGRAL/IBAS trigger). We stacked the images with good conditions. We did not detect any uncatalogued sources within the enhanced Swift/XRT error region (Goad et al. GCN 35220). We obtained the 5-sigma limits of the stacked images as follows.

T0+[hour] | MID-UT | T-EXP[sec] | 5-sigma limits
------------------------------------------------------------------------------------------------
4.50 | 2023-11-29 09:35:41 | 7140 | g'>19.4, Rc>19.0, Ic>18.4
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the trigger
T-EXP: Total Exposure time

We used the PS1 catalog for flux calibration. The catalog magnitudes in PS1 g, r and i bands were converted to our g', Rc and Ic band magnitudes following Tonry et al. (2012), Table 6. 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: GRB231129C
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35244
SUBJECT: GRB 231129C: AGILE detection
DATE:    23/12/01 11:28:51 GMT
FROM:    Gabriele Panebianco <gabriele.panebianco@inaf.it>

G. Panebianco (Univ. Bologna - INAF/OAS Bologna), A. Bulgarelli (INAF/OAS Bologna),
C. Pittori, F. Verrecchia (SSDC, and INAF/OAR),
M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata),
A. Argan, M. Cardillo, C. Casentini, Y. Evangelista, L. Foffano, G. Piano (INAF/IAPS),
L. Baroncelli, A. Ciabattoni, 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), 
F. Longo (Univ. Trieste, and INFN Trieste), A. Ursi (ASI and INAF/IAPS),
I. Donnarumma, E. Menegoni (ASI),  A. Giuliani (INAF/IASF-Mi),
P.W. Cattaneo (INFN Pavia), F.  Cutrona (Univ. Milano Bicocca) and P. Tempesta (TeleSpazio) 
report on behalf of the AGILE Team:

The AGILE satellite detected the bright and long GRB 231129C at T0 = 2023-11-29 19:10:18 s (UTC),
reported by Fermi (GCNs #35217, #35221, #35227, #35238), BALROG (GCN #35222),
MAXI/GSC (GCN #35223), Swift (GCNs #35225, #35234, #35242), CALET (GCN #35228),
AstroSAT CZTI (GCN #35230), GECAM-B (GCN #35231), Glowbug (GCN #35235),
GRBAlpha (GCN #35236), MASTER OT (#35240).

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 pulse lasted about 10 s and it released a total number
of 7648 counts in the MCAL detector (above a background rate of 525 Hz)
and 49403 counts in the AC-Top detector (above a background rate of 2900 Hz).

The AGILE ratemeters light curves can be found at
http://www.agilescienceapp.it/notices/GRB231129C_AGILE_RM_ND.png .

At the detection time the GRB location was occulted by the Earth for the AGILE GRID instrument.

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: GRB231128A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35246
SUBJECT: GRB 231128A: VZLUSAT-2 detection
DATE:    23/12/01 16:00:49 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 231128A (Fermi/GBM detection: GCN 35206) 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 2023-11-28 11:44:15 UTC. The T90 duration is 24 s and the significance during T90 reaches 9.7 sigma.

The light curve obtained by VZLUSAT-2 is available here:
https://vzlusat2.konkoly.hu/static/share/GRB231128A_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: GRB231129B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35247
SUBJECT: GRB 231129B: Swift-XRT observations
DATE:    23/12/01 16:04:46 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

T. Sbarrato (INAF-OAB), A. Tohuvavohu (U. Toronto), D.N. Burrows (PSU),
J. D. Gropp (PSU), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB) and P.A.
Evans (U. Leicester) reports on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the MAXI-detected
burst GRB 231129B in a series of observations tiled on the sky. The
total exposure time is 2.0 ks, distributed over 7 tiles; the maximum
exposure at a single sky location was 659 s. The data were collected
between T0+12.3 ks and T0+18.0 ks, and are entirely in Photon Counting
(PC) mode. 

No X-ray sources have been detected. The 3-sigma upper limit in the
field (not including the regions where the tiles overlap) ranges from
~0.03 to ~0.07 ct s^-1, corresponding to a 0.3-10 keV observed flux of
1.1e-12 to 2.7e-12 erg cm^-2 s^-1 (assuming a typical GRB spectrum).

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_GRB00116.

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


GRB_name: GRB231129A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35248
SUBJECT: GRB 231129A: VZLUSAT-2 detection
DATE:    23/12/01 17:04:23 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 231129A (Swift/BAT detection: GCN 35208; INTEGRAL/IBIS detection: GCN 35209; GECAM-C detection: GCN 35210) 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 2023-11-29 05:06:01 UTC. The T90 duration is 157 s and the significance during T90 reaches 21 sigma.

The light curve obtained by VZLUSAT-2 is available here:
https://vzlusat2.konkoly.hu/static/share/GRB231129A_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: GRB231129C
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35249
SUBJECT: GRB 231129C: PROMPT optical upper limits for the MAXI/GSC X-ray counterpart and the MASTER afterglow candidate 
DATE:    23/12/01 18:24:28 GMT
FROM:    Hank Corbett at UNC,Chapel Hill <htcorbett4@gmail.com>

Hank Corbett (University of North Carolina), Kendall Ackley (University of Warwick), Daniel E. Reichart (UNC), Joshua B. Haislip (UNC), Vladimir V. Kouprianov (UNC), Megan Dubay (UNC)

We obtained 2x300s unfiltered exposures of the 90% error region of the MAXI/GSC X-ray transient (Kawakubo et al. GCN 35223) with the 0.8-m PROMPT-7 telescope. Exposures began at 2023-11-30 00:53 UT. Relative to images of the field 24-hours later, we do not detect any new sources within the MAXI/GSC error region with an upper limit of 21.9 calibrated to g-band reference stars from the ATLAS reference catalog (Tonry 2018). 

We also observed the position of the MASTER OT detection (Antipov et al, GCN 35240) in a series of unfiltered 6x200s exposures beginning at 2023-12-01 01:56 UT, and do not detect the transient in the stacked image to an upper limit of 22.5. The field also includes the 90%  error circle for the Swift XRT candidate at RA 00:44:42.45 Dec -81:59:37.0, and we detect no transient sources to an upper limit of 22.5. We note that the error circle closely aligns with a faint (m_G=19.96) red star (Gaia 4630203649665987840).  

Date | Filter | Mag  | Exp time (s)
---------------------------------------------------------------
2023-11-30 00:53 UT | Open  | > 21.9 @ 5-sigma | 2x300 s
2023-11-30 00:53 UT | Open  | > 22.5 @ 5-sigma | 6x200 s 


GRB_name: GRB231129C
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35251
SUBJECT: GRB 231129C: Swift-XRT afterglow detection
DATE:    23/12/02 14:30:18 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

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

Swift-XRT has conducted further observations of the field of the
Fermi/GBM-detected burst GRB 231129C. The observations now extend from
T0+34.8 ks to T0+172.6 ks. The source previously reported, "Source 2",
is believed to be the afterglow.  The position of this source is RA,
Dec=11.1769, -81.9936 which is equivalent to:

RA (J2000): 00:44:42.45
Dec(J2000): -81:59:37.0

with an uncertainty of 9.5 arcsec (radius, 90% confidence).  This
position is 22.4 arcmin from the Fermi/GBM position.  We cannot
determine at the present time whether the source is fading.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00021633.
The results of the full analysis of the tiled XRT observations are
available at https://www.swift.ac.uk/xrt_products/TILED_GRB00117.

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


GRB_name: GRB231203A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35252
SUBJECT: GRB 231203A: Fermi GBM Final Real-time Localization
DATE:    23/12/03 07:11:59 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 LONG GRB

At 07:01:30 UT on 3 Dec 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231203A (trigger 723279695.772024 / 231203293).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 239.7, Dec = -49.8 (J2000 degrees, equivalent to J2000 15h 58m, -49d 47'), with a statistical uncertainty of 7.1 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/bn231203293/quicklook/glg_skymap_all_bn231203293.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/bn231203293/quicklook/glg_healpix_all_bn231203293.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231203293/quicklook/glg_lc_medres34_bn231203293.gif


GRB_name: GRB231203B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35253
SUBJECT: The Fermi GBM team reports the detection of a likely SHORT GRB
DATE:    23/12/03 22:30:35 GMT
FROM:    Bagrat Mailyan at Florida Tech <mbagrat@gmail.com>

At 19:56:04 UT on 3 Dec 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231203B (trigger 723326169/ 231203831).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 197.3, Dec = +42.54 (J2000 degrees, equivalent to J2000 13h 09m, 42d 32'), with a statistical uncertainty of 15.9 degrees.
The angle from the Fermi LAT boresight is 17.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231203831/quicklook/glg_skymap_all_bn231203831.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/bn231203831/quicklook/glg_healpix_all_bn231203831.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231203831/quicklook/glg_lc_medres34_bn231203831.gif


GRB_name: GRB231129C
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35256
SUBJECT: Konus-Wind detection of GRB 231129C
DATE:    23/12/04 15:14:55 GMT
FROM:    Alexandra Lysenko at Ioffe Institute <alexandra.lysenko@mail.ioffe.ru>

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

The bright long-duration GRB 231129C
(Fermi-GBM detection: Sharma et al., GCN Circ. 35227;
MAXI/GSC detection: Kawakubo et al., GCN Circ. 35223;
CALET detection: Kawakubo et al., GCN Circ. 35228;
AstroSat CZTI detection: Waratkar et al., GCN Circ. 35230;
GECAM-B detection: Zheng et al., GCN Circ. 35231;
Swift-XRT detection: Gropp et al., GCN Circ. 35234;
Glowbug detection: Cheung et al., GCN Circ. 35235;
GRBAlpha detection: Dafcikova et al., GCN Circ. 35236;
Fermi-LAT detection: Arimoto et al., GCN Circ. 35238;
AGILE detection: Panebianco et al., GCN Circ. 35244)
triggered Konus-Wind at T0=69016.319 s UT (19:10:16.319).

The burst light curve shows a bright, multi-peaked pulse
featuring a very strong hard-to-soft spectral evolution.
The pulse starts at ~T0-0.2 and has a total duration of ~9.6 s.
The emission is seen up to ~15 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB231129_T69016/

As observed by Konus-Wind, the burst
had a fluence of 8.60(-0.23,+0.24)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+0.106s,
of 4.16(-0.52,+0.54)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+12.800 s)
is best fit in the 20 keV - 20 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.17(-0.06,+0.06),
the high energy photon index beta = -2.95(-0.12,+0.10),
the peak energy Ep = 202(-6,+6) keV
(chi2 = 151/97 dof).

The spectrum near the maximum count rate
(measured from T0 to T0+0.256 s)
is best fit in the 20 keV - 20 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.20(-0.14,+0.15)
and Ep = 782(-52,+55) keV (chi2 = 69/51 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -3.3
(chi2 = 69/50 dof).

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


GRB_name: GRB231203A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35257
SUBJECT: GRB 231203A: Swift/BAT-GUANO detection of a burst outside the coded FOV 
DATE:    23/12/04 16:20:25 GMT
FROM:    Jimmy DeLaunay at Penn State <delauj2@gmail.com>

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

Swift/BAT did not localize GRB 231203A onboard (T0: 2023-12-03T07:01:30.77 UTC, Fermi trig 723279723) 

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), performed on the temporal window [T0-20 s, T0+20 s], detects the burst with a sqrt(TS) of 13.6 in a 2.048 s analysis time bin, starting at T0. 

NITRATES results are consistent with a burst coming from outside the FOV, with DeltaLLHOut of 2.64.

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: GRB231205A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35263
SUBJECT: GRB 231205A: Fermi GBM Final Real-time Localization
DATE:    23/12/05 02:35:45 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 SHORT GRB

At 02:25:11 UT on 5 Dec 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231205A (trigger 723435916.407408 / 231205101).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 206.1, Dec = 22.8 (J2000 degrees, equivalent to J2000 13h 44m, 22d 48'), with a statistical uncertainty of 3.1 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/bn231205101/quicklook/glg_skymap_all_bn231205101.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/bn231205101/quicklook/glg_healpix_all_bn231205101.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231205101/quicklook/glg_lc_medres34_bn231205101.gif


GRB_name: GRB231205A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35266
SUBJECT: GRB 231205A: GECAM-B detection of a short burst
DATE:    23/12/05 03:48:51 GMT
FROM:    tanwj@ihep.ac.cn

GRB 231205A: GECAM-B detection of a short burst

Wenjun Tan, Shaolin Xiong, report on behalf of the GECAM team:

GECAM-B was triggered in-flight by a short burst, GRB 231205A
at 2023-12-05T02:25:11.450 UTC(T0), which was also observed by 
Fermi/GBM (Fermi/GBM team, GCN 35263).

According to the realtime alert data of GECAM-B, this burst consists 
of one bright short pulse followed by weaker emission with a total 
duration (T90) of about ~0.3 sec (30-1020 keV).

Using the automatic on-ground localization pipeline with the realtime alert data, 
GECAM-B localized this burst to the following position (J2000): 
Ra: 202.8 deg 
Dec: 26.8 deg
Err: 6.1 deg (1-sigma, statistical only)
GECAM location is consistent with that of Fermi/GBM within the error.

The time-averaged spectrum of GECAM-B realtime data from about T0-0.05 s to T0 could be
adequately fit by a cut-off power-law with a fluence about 1.10E-6 erg/cm^2 in 20-1000 keV. 

We note that these results are based on realtime alert data and thus very preliminary. 

Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor
(GECAM) mission originally consists of two microsatellites (GECAM-A and GECAM-B)
launched in Dec. 2020. As the third member of GECAM constellation, 
GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. 
GECAM mission is funded by the Chinese Academy of Sciences (CAS).


GRB_name: GRB231204A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35267
SUBJECT: GRB 231204A: AstroSat CZTI detection
DATE:    23/12/05 14:16:15 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 the long-duration GRB 231204A which was also detected by Fermi-GBM (Fermi GBM Team, GCN Circ. 35258).

The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2023-12-04 20:00:04.5 UTC. The measured peak count rate associated with the burst is 230.7 (+39.0, -34.4) counts/s above the background in the combined data of all quadrants, with a total of 1319 (+234, -237) counts. The local mean background count rate was 347.5 (+2.1, -2.9) counts/s. Using cumulative rates, we measure a T90 of 13 (+7, -5) s.

It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2023-12-04 20:00:06.6 UTC. The measured peak count rate is 873.2 (+83.1, -58.1) counts/s above the background in the combined Veto data of all quadrants, with a total of 6070 (+508, -547) counts. The local mean background count rate was 1532.5 (+4.8, -5.7) counts/s. We measure a T90 of 12 (+8, -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: GRB231205A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35268
SUBJECT: GRB 231205A: joint location of multiple instruments by ETJASMIN 
DATE:    23/12/05 16:33:30 GMT
FROM:    yqzhang_cl@163.com

Yanting Zhang, Shaolin Xiong, Yue Huang, Shuo Xiao, Xiaoyun Zhao, Ping Wang, 
report on behalf of the GECAM team:

The short burst, GRB 231205A, has been detected by GECAM-B (Tan et al., GCN 35266), Fermi/GBM (Fermi/GBM team, GCN 35263) and INTEGRAL/SPI-ACS. With the ETJASMIN pipeline (Energetic Transients joint analysis system for Multi-INstrument, Xiao et al., MNRAS, 514, 2397, 2022) and the realtime data of GECAM-B, INTEGRAL/SPI-ACS and Fermi/GBM, we did a low-latency joint location for this burst.

Firstly, we applied the Li-CCF method (Xiao et al., ApJ, 920, 43, 2021) to the realtime high temporal resolution (~1 ms) light curve of GECAM-B and the low-latency public 50 ms light curve of INTEGRAL/SPI-ACS, and derived the triangulation location as the following annuli:

--------------------------------------------------------------------------------------------------
Annulus                 Ra (deg)      Dec (deg)     Radius (deg)      Radius-Error (deg, 3sigma)
GECAM-B + SPI-ACS       209.519       59.889        40.961            1.272
--------------------------------------------------------------------------------------------------

Then, we combined this annulus location, the stand-alone locations provided by GECAM-B (Tan et al., GCN 35266) and Fermi/GBM (Fermi/GBM team, GCN 35263), as well as the Earth occultation of these instruments, and derived a refined location, which is much smaller than stand-alone ones. 

This refined location (~3 sigma region) could be approximately described by a polygon region,
whose center and corners are:

--------------------------------------
            Ra (deg)      Dec (deg)
Center      205.313   19.155   
Corner1     215.859       19.155
Corner2     209.883       18.724
Corner3     202.148       18.871
Corner4     194.766       20.427
Corner5     205.313       19.524
--------------------------------------

For this refined location, the sky map and probability data could be found at:
Sky map: http://twiki.ihep.ac.cn/pub/GECAM/GRBList/GRB231205A-jointLoc-skymap-v01.png
Data file: http://twiki.ihep.ac.cn/pub/GECAM/GRBList/GRB231205A-jointLoc-healpix-v01.fits


ETJASMIN is developed for joint observation of high energy transients by the GECAM team.
We acknowledge the public data of Fermi/GBM and INTEGRAL/SPI-ACS. 


GRB_name: GRB231205B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35269
SUBJECT: GRB 231205B: Swift detection of a burst
DATE:    23/12/05 17:11:16 GMT
FROM:    K.L. Page at U Leicester <klp5@leicester.ac.uk>


P. A. Evans (U Leicester), S. Dichiara (PSU),
N. J. Klingler (GSFC/UMBC/CRESSTII), K. L. Page (U Leicester),
D. M. Palmer (LANL), T. M. Parsotan (GSFC/UMBC/CRESSTII) and
M. A. Williams (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 16:43:59 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 231205B (trigger=1200812).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 54.154, +27.146 which is 
   RA(J2000) = 03h 36m 37s
   Dec(J2000) = +27d 08' 47"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single peak
structure with a duration of about 40 sec.  However there
may be activity before the start of the immediately-available
data, as the burst occurred during a pre-planned slew.  The peak count
rate was ~6000 counts/sec (15-350 keV), at T-3, before the
nominal trigger time. 

The XRT began observing the field at 16:47:54.0 UT, 234.5 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 54.14912, 27.14099 which is equivalent
to:
   RA(J2000)  = 03h 36m 35.79s
   Dec(J2000) = +27d 08' 27.6"
with an uncertainty of 3.5 arcseconds (radius, 90% containment). This
location is 23 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. No
spectrum from the promptly downlinked event data is yet available to
determine the column density. 

UVOT took a finding chart exposure starting 237 seconds after the
BAT trigger. No credible afterglow candidate has been found in
the initial data products. 

Burst Advocate for this burst is P. A. Evans (pae9 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: GRB231205B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35270
SUBJECT: GRB 231205B: AKO Optical Upper Limit
DATE:    23/12/05 18:46:35 GMT
FROM:    Mohammad Odeh at Al Khatim Observatory M44 <mshodeh@gmail.com>

Mohammad Odeh (Al-Khatim Observatory, AKO, operated by the International
Astronomical Center in Abu Dhabi, UAE), and Dalya Akl (American University
of Sharjah, UAE), report:

We observed the field of GRB 231205B, which was detected by Swift/BAT (GCN
35269) with our 0.36m f/7.7 robotic telescope on December 05 starting at
17:37:44 UT (corresponding to 0.9 hours from the GRB trigger time) using an
(Ic) filter.

We obtained 17x180s images. We do not detect a credible source within the
Swift-XRT error region (Evans et al., GCN 35269). The following 5-sigma
 upper limit is calculated using the ATLAS catalog as a reference: Ic =
20.0.


GRB_name: GRB231204A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35272
SUBJECT: GRB 231204A: CALET Gamma-Ray Burst Monitor detection
DATE:    23/12/05 19:10:01 GMT
FROM:    Yuta Kawakubo at Louisiana State University <kawakubo1@lsu.edu>

T. Tamura (Kanagawa U), A. Yoshida, T. Sakamoto, S. Sugita (AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA),
Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (Waseda U),
Y. Shimizu (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 231204A (Fermi GBM Final Real-time Localization: 
Fermi GBM team, GCN Circ. 35258; AstroSat CZTI detection: 
Waratkar et al., GCN Circ. 35267) triggered the CALET Gamma-ray
Burst Monitor (CGBM) at 20:00:00.75 UTC on 4 December 2023
(http://cgbm.calet.jp/cgbm_trigger/flight/1385755095/).
The burst signal was seen by only the SGM detector.

The burst light curve shows a weak pulse that starts
at T+3.1 sec, peaks at T+4.1 sec, and ends at T+7.9 sec.
The T90 and T50 durations measured by the SGM data are 4.5 +/- 0.5 sec
and 2.5 +/- 0.1 sec (40-1000 keV), respectively.

The ground-processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1385755095/index.html

The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.


GRB_name: GRB231204A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35274
SUBJECT: GRB 231204A: Glowbug gamma-ray detection
DATE:    23/12/05 20:09:43 GMT
FROM:    C.C. Cheung at Naval Research Lab <Teddy.Cheung@nrl.navy.mil>

C.C. Cheung, M. Kerr, J. E. Grove, R. Woolf (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge (MSFC), and M.S. Briggs (UAH) report:                                                                                                                                                                                                                                                    

The Glowbug gamma-ray telescope [1,2], operating on the International Space Station, reports the detection of GRB 231204A, which was also detected by Fermi/GBM, AstroSat/CZTI, and CALET (GCN 35258, 35267, 35272).

Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2023-12-04 20:00:02.808 with a duration of 11.3 s and a total significance of about 27.2 sigma.  The light curve comprises a dominant triple-peaked structure from T0 to ~T0+6s and a fainter pulse at ~T0+9s.

Using a standard power-law function with an exponential high-energy cutoff [3] to model the emission over this duration results in a photon index dN/dE~E^x of x=0.6 and a cutoff energy ("Epeak") of 619 keV.  The modeled 10-10000 keV fluence is 1.3e-05 erg/cm^2.

The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.

Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC.  It was launched on 2023 March 15 aboard the Department of Defense Space Test Programâ€™s STP-H9 to the ISS.  The detector comprises 12 large-area (15 cm x 15 cm) CsI:Tl panels covering the surface of a half cube, and two hexagonal (5-cm diameter, 10-cm length) CLLB scintillators, giving it a large field of view (instantaneous FoV ~2/3 sky) over a wide energy band of 50 keV to >2 MeV.

[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959
[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O
[3] Goldstein, A. et al. 2020, ApJ 895, 40, arXiv :1909.03006

Distribution Statement A: Approved for public release.  Distribution is unlimited.


GRB_name: GRB231205B
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35275
SUBJECT: GRB 231205B: Enhanced Swift-XRT position
DATE:    23/12/06 00:40:47 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 1474 s of XRT Photon Counting mode data and 4 UVOT
images for GRB 231205B, 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 = 54.14875, +27.14134 which is equivalent
to:

RA (J2000): 03h 36m 35.70s
Dec (J2000): +27d 08' 28.8"

with an uncertainty of 2.0 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: GRB231205A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35277
SUBJECT: GRB 231205A: DDOTI Upper Limits on the Afterglow
DATE:    23/12/06 01:21:44 GMT
FROM:    Kin O. C. L. Mendoza at Instituto de Astronoma, UNAM <koclopez@astro.unam.mx>

OcÃ©lotl Lopez (UNAM), Alan M. Watson (UNAM), Rosa L. Becerra (UNAM),
Margarita Pereyra (UNAM), Nat Butler (ASU), Simone Dichiara (Penn state
university), Diego Gonzalez (UNAM), William H. Lee (UNAM), Alexander
Kutyrev (GSFC/UMD), Srihari Ravi (ASU) and Eleonora Troja (Tor Vergara
Roma) report:



We observed the field of the Fermi GBM GRB 231205A (Fermi GBM Team, GCN
Circ. 35263) with the DDOTI wide-field imager at the Observatorio
AstronÃ³mico Nacional on Sierra San Pedro MÃ¡rtir (
http://ddoti.astroscu.unam.mx) from 2023-12-05 12:55:13 to 13:10:57 UTC
(10.50 to 11.75 hours after the trigger).


We observed a region of 7 degrees in RA by 7 degrees in declination
centered on the Fermi GBM Final Position of RA = 206.1 and Dec = 22.8
(J2000 degrees). This region contains 1 instrumental field or about 49
square degrees. We obtained 13.6 minutes of exposure per instrumental field
in the w filter. We obtained AB photometry by calibration against the APASS
catalog.


We detect no likely candidates for the afterglow to our 10-sigma upper
limits of w = 18.89-19.41 (inter-quartile).


We thank the staff of the Observatorio AstronÃ³mico Nacional on San Pedro
MÃ¡rtir.


GRB_name: GRB231205B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35278
SUBJECT: GRB 231205B: LCOGT Optical Upper Limits
DATE:    23/12/06 04:03:52 GMT
FROM:    Robert Strausbaugh at Eastern Illinois University <rstrausbaugh@eiu.edu>

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

We observed the Swift GRB 231205B field (Evans et al., GCN 35269) with the LCOGT 1-meter Sinistro instrument at the McDonald Observatory, USA site, on December 6, from 01:40 to 02:12 UT (corresponding to 8.95 to 9.48 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 error region around the enhanced XRT position (Osborne et al., GCN 35275) in either band, consistent with other non-detections (Odeh et al., GCN 35270)

The following 5-sigma upper limits are calculated using the PanSTARRS catalog as reference:

r > 22.6
i > 21.9

These magnitudes are not corrected for galactic extinction.


GRB_name: GRB231205B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35279
SUBJECT: GRB 231205B: GECAM-B detection of a long burst 
DATE:    23/12/06 05:43:25 GMT
FROM:    Yue Wang <m18509381757@163.com>

Jia-Cong Liu , Shao-Lin Xiong report on behalf of the GECAM team:

GECAM-B was triggered in-flight by a long burst, GRB 231205B, at 2023-12-05T16:43:34.100 UTC (T0), which was also observed by Swift/BAT (GCN #35269) . 

According to the realtime alert data, the GECAM-B light curve shows roughly two peaks with a total duration of ~40 sec (15-1050 keV). 

The time-averaged spectrum of GECAM-B realtime data from about T0 to T0+4 s could be
adequately fit by a Band function with a fluence about 8.20E-7 erg/cm^2 in 20-1000 keV. 

The GECAM light curve could be found here: 
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/GRB231205B_LC.png

GECAM location is consistent with that of Swift/BAT within the error.
We note that these results are based on realtime alert data and thus very preliminary. Refined analysis will be reported later.

Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor(GECAM) mission originally consists of two microsatellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS).


GRB_name: GRB231205B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35280
SUBJECT: GRB 231205B: Nanshan/HMT optical upper limit
DATE:    23/12/06 06:40:55 GMT
FROM:    Dong Xu at NAOC/CAS <dxu@nao.cas.cn>

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

We observed the field of GRB 231205B detected by Swift (Evans et al., GCN 35269) using the HMT-0.5m telescope located at Nanshan, Xinjiang, China. Observations started at 16:57:41 UT on 2023-12-05, i.e., 13.7 mins after the Swift/BAT trigger, we obtained a series of 20 s, 40 s, 60 s, 90 s, 120 s, 200 s frames without any filter.

No optical source is detected in our stacked image at the Enhanced XRT position (Osborne et al., GCN 35275), down to the 3-sigma limiting magnitude of m(r)>21.3 mag(AB) @ 0.61 hr post-burst, calibrated with the nearby PanSTAR field in the Sloan r-filter and the magnitude is not corrected for Galactic extinction.


GRB_name: GRB231205B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35281
SUBJECT: GRB 231205B: Gaoyazi/GOT optical upper limit
DATE:    23/12/06 06:45:03 GMT
FROM:    Dong Xu at NAOC/CAS <dxu@nao.cas.cn>

S.Q. Jiang, S.Y. Fu, X. Liu, Z.P. Zhu, J. An, T.H. Lu, D. Xu (NAOC), L.F. Huo, M.M. Yang, S.W. Luo, Z. K. Feng (XJTS) report:

We observed the field of GRB 231205B detected by Swift (Evans et al., GCN 35269) using the GOT-0.5m telescope located at Gaoyazi, Xinjiang, China. Observations started at 16:46:51 UT on 2023-12-05, i.e., 172 s after the Swift/BAT trigger, and we obtained 5x3, 5x5, 5x10, 5x15, 5x20, 5x40, 10x60, 10x90, 10x120, 10x200 s frames with the Sloan r filter.

No optical counterpart is detected in our stacked image at the Enhanced XRT position (Osborne et al., GCN 35275), down to the following 3-sigma limiting magnitude of m(r)>21.2 @ 0.80 hr
calibrated with nearby PanSTARRS stars and the magnitude is not corrected for Galactic extinction.


GRB_name: GRB231205B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35282
SUBJECT: GRB 231205B: Zadko observatory - Gingin optical observations
DATE:    23/12/06 07:38:19 GMT
FROM:    Bruce Gendre at UVI <bruce.gendre@gmail.com>

B. Gendre, E. Moore, E. Van Dongen, F. Panther,
D. Coward, J. A. Moore (OzGrav-UWA), A. Klotz (IRAP-CNRS-OMP),
and P. Thierry (AGORA),
report:

We imaged the field of GRB 231205B detected by SWIFT
(Evans et al., GCN 35269, trigger 1200812) with the
Zadko robotic telescope (D=100cm) located at Gingin, Australia.

The observations started 201.6s after the GRB trigger (126.1s
after the notice). The elevation of the field decreased from
25 degrees above horizon and weather conditions were poor,
with high altitude clouds.

The date of trigger : t0 = 2023-12-05T16:43:59.500

The first image is a 10.0s exposure in tracking mode. At the
position of the XRT afterglow (Osborne et al, GCN 35275), we
do not detect any OT with a limiting magnitude of:
t0+201.6s to t0+211.6s : R > 16.2

We co-added a series of exposures:
t0+217.3s to t0+344.2s : R > 17.2

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

N.B. Galactic coordinates are lon=162.4895 lat=-22.7655
and the galactic extinction in R band is 0.3 magnitudes
estimated from D. Schlegel et al. 1998ApJ...500..525S.

This message may be cited.


GRB_name: GRB231206A
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35283
SUBJECT: GRB 231206A: GECAM-B detection of a short burst 
DATE:    23/12/06 07:38:51 GMT
FROM:    Yue Wang <m18509381757@163.com>

Jia-Cong Liu , Shao-Lin Xiong report on behalf of the GECAM team:

GECAM-B was triggered in-flight by a short burst, GRB 231206A, at 2023-12-06T02:37:43.250 UTC (T0), which was also observed by INTEGRAL/SPI-ACS . 

According to the realtime alert data, the GECAM-B light curve shows a peak with a total duration of ~0.5 sec (15-1050 keV). 

The time-averaged spectrum of GECAM-B realtime data from about T0 to T0+0.1 s could be
adequately fit by a cut-off power-law with a fluence about 6.04E-6 erg/cm^2 in 20-1000 keV. 

Using the automatic in-flight localization pipeline with the realtime alert data, 
GECAM-B localized this burst to the following position (J2000): 
RA: 313.15 deg 
DEC: -23.54 deg
Err: 8.0 deg (1-sigma, statistical only)
The systematic error of this location is estimated to be several degrees.

The GECAM light curve could be found here: 
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/GRB231206A_LC.png

We note that these results are based on realtime alert data and thus very preliminary. Refined analysis will be reported later.

Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor(GECAM) mission originally consists of two microsatellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS).


GRB_name: GRB231205B
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35284
SUBJECT: GRB 231205B : MITSuME Akeno optical upper limits
DATE:    23/12/06 08:05:47 GMT
FROM:    Mahito Sasada at Tokyo Institute of Technology <sasada@hp.phys.titech.ac.jp>

M. Sasada, I. Takahashi, M. Niwano, S. Sato, N. Higuchi, S. Hayatsu, H. Takei,  H. Seki, Y. Yatsu and N. Kawai  (Tokyo Tech) report on behalf of the MITSuME collaboration:

We observed the field of GRB 231205B (Evans et al., GCN 35269) with the optical three-color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50-cm telescope Akeno. 

The observation started at 2023-12-05 16:46:02 UT (123 seconds after the Swift/BAT trigger). We stacked the images with good conditions. We did not detect any uncatalogued sources within the enhanced Swift/XRT error region (Osborne et al., GCN 35275), consistent with other non-detections (Odeh et al., GCN 35270; Strausbaugh et al., GCN 25278; Jiang et al., GCN 35280; Jiang et al., GCN 35281, Gendre et al., GCN 35282). We obtained the 5-sigma limits of the stacked images as follows.

T0+[sec] | MID-UT | T-EXP[sec] | 5-sigma limits
------------------------------------------------------------------------------------------------
517 | 2023-12-05 16:52:36 | 100 | g'>17.2, Rc>16.6, Ic>16.2
5970 | 2023-12-05 18:23:29 | 420 | gâ€™>17.5, Rc>17.5, Ic>17.2
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the trigger
T-EXP: Total Exposure time

We used the PS1 catalog for flux calibration. The catalog magnitudes in PS1 g, r and i bands were converted to our g', Rc and Ic band magnitudes following Tonry et al. (2012), Table 6. 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: GRB231206A
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35285
SUBJECT: GRB 231206A: GECAM-B detection of a short burst (correction)
DATE:    23/12/06 08:32:26 GMT
FROM:    Yue Wang <m18509381757@163.com>

Jia-Cong Liu , Shao-Lin Xiong report on behalf of the GECAM team:

There is a typo in our previous report (GCN 35283). Here we make the correction:
The time-averaged spectrum of GECAM-B realtime data from about T0-0.1 s to T0 could be
adequately fit by a cut-off power-law with an average flux of about 6.04E-6 erg/cm^2/s in 20-1000 keV. 

We are very sorry for any inconvenience.


GRB_name: GRB231205B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35286
SUBJECT: GRB 231205B: r'-band observations from MISTRAL at Observatoire de Haute-Provence
DATE:    23/12/06 09:41:50 GMT
FROM:    Christophe Adami at LAM <christophe.adami@lam.fr>

C. Adami (LAM), E. Le Floc'h, D. GÃ¶tz, F. SchÃ¼ssler,D. Turpin (CEA Paris-Saclay), A. de Ugarte Postigo (OCA/CNRS), 
S. Basa (LAM), S. D. Vergani (GEPI, Obs. de Paris), report on behalf of a larger collaboration:

We observed the field of GRB231205B (GCN 35269; Evans et al., GCN 35270, Odeh et al.) using the MISTRAL spectro-imager 
mounted at the T193cm telescope at Observatoire de Haute-Provence (France) under a poor seeing of ~3arcsec.

We began our observations on 2023 05 December 20:56:18 UT (~5.2h after the trigger time) with a series of r'-band (300s + 
6x720s) images. Last image was taken at 22:26:25 UT. Consistently with Evans et al. and Odeh et al., we do not detect any 
credible optical counterpart to GRB231205B within the GCN 35269 Swift XRT error box.

Using the r-band PanStarr public image, the faintest detected object in our r-band image with a measured PanStarr magnitude is
at rmeanKronmag=20.65.
Using the i-band PanStarr public image, the faintest detected object in our r-band image with a measured PanStarr magnitude is
at imeanKronmag=21.60.

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


GRB_name: GRB231205B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35287
SUBJECT: GRB 231205B: NUTTelA-TAO / BSTI Early Optical Limits
DATE:    23/12/06 09:54:28 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), M. Krugov (FAI) and E. Abdikamalov (NU) 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 231205B, 10 s after receipt an automated GCN / BAT position alert, observing in Sloan g', r' and i' bands, with the Burst Simultaneous Three-Channel Imager (BSTI; Grossan, Kumar & Smoot 2019, JHEA, 32, 14).

We started observations at 16:45:33 UT on 2023-12-05, 94 s after the BAT trigger. Observations were made in clear conditions. No source consistent with the XRT (J.P. Osborne et al., GCN Circ. 35275) was detected. We report the following results:

start time  t-t0(s)  end time    UL g'   UL r'  ULi'   exposure_time (s)
-----------------------------------------------------------------------
16:45:33     94     16:46:29     19.9     19.5    18.3          52.5
16:46:43    164     16:49:13   20.3     19.9    19.0          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 0.5 s for g' and r' (these sub-second exposures are read-noise suppressed by our EMCCD cameras, with high gain electron multiplication active; other images are taken in conventional CCD operation mode), and 7.5 s for i'. The second row corresponds to co-adds from a continuing series of 3 s exposures for g' and r', and 15 s for i'.  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: GRB231129C
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35288
SUBJECT: GRB 231129C: ASIM MXGS observation and localization
DATE:    23/12/06 12:42:06 GMT
FROM:    Martino Marisaldi at U of Bergen, Norway <martino.marisaldi@uib.no>

M. Marisaldi (University of Bergen), A. Mezentsev (University of Bergen), P.Connell, Javier Navarro-Gonzalez (University of Valencia), 
N. Ã˜stgaard (University of Bergen), V. Reglero (University of Valencia) 
and T. Neubert (DTU Space) report on behalf of the ASIM Team:
 
At  19:10:18 UT on 29 November 2023, the Atmosphere-Space Interactions Monitor (ASIM)
mission triggered on the long bright GRB 231129C.
 
The burst was also detected by Fermi-GBM (Sharma et al., GCN Circ. 35221, and Sharma et al., GCN Circ. 227),
MAXI/GSC (Kawakubo et al., GCN Circ. 35223), CALET (Shimizu et al., GCN Circ. 35228),
AstroSat CZTI (Waratkar et al., GCN Circ. 35230), GECAM-B (Zheng et al., GCN Circ. 35231),
Swift-XRT (Gropp et al., GCN Circ. 35234), Glowbug (Cheung et al., GCN Circ. 35235),
GRBAlpha (Dafcikova et al., GCN Circ. 35236), Fermi-LAT (Arimoto et al., GCN Circ. 35238,
AGILE (Panebianco et al., GCN Circ. 35244), and Konus-Wind (Lysenko et al., GCN Circ. 35256).
 
Photon by photon data with <1 microsecond time resolution have been
collected for a time interval of 19 seconds.
The emission is detected in the MXGS High Energy Detector (HED), sensitive in the range 0.3 to >30 MeV,  
and in the MXGS Low Energy Detector (LED), sensitive in the range 0.05 to 0.4 MeV.
 
In January 2022 ASIM was relocated so that the MXGS coded mask imaging system is pointing towards the Earthâ€™s limb, observing a large fraction of unocculted sky, therefore enabling localization of the GRB prompt emission.
This GRB was observed within the MXGS Field of View resulting in a very high significant localization (>100 sigma) at
 
R.A.,Dec(2000) = 00:51:12.56  -81:45:35.5
 
consistent within a 25 arcmin error (radius, 99% confidence level) with the Swift-XRT X-ray afterglow (Gropp et al., GCN Circ. 35251) and the MASTER OT detection (Antipov et al., GCN Circ.35240).

ASIM is an ESA mission onboard the International Space Station dedicated to the 
observation of Terrestrial Gamma-ray Flashes (TGFs) and Transient Luminous Events (TLEs) 
operative since June 2018 (Neubert et al., Space Sci Rev (2019) 215:26 
https://doi.org/10.1007/s11214-019-0592-z  ). 
The payload includes the Modular X- and Gamma-Ray Sensor (MXGS) 
(Ã˜stgaard et al., Space Sci Rev (2019) 215:23 https://doi.org/10.1007/s11214-018-0573-7  ), 
and the the Modular Multispectral Imaging Array  (MMIA) 
(Chanrion et al., Space Sci Rev (2019) 215:28 https://doi.org/10.1007/s11214-019-0593-y  ). 
The ASIM Science Data Centre (ASDC) website is https://asdc.space.dtu.dk/
 


GRB_name: GRB231205B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35289
SUBJECT: GRB 231205B: REM optical/NIR upper limits
DATE:    23/12/06 14:26:13 GMT
FROM:    Riccardo Brivio <riccardo.brivio@inaf.it>

R. Brivio, M. Ferro, P. D'Avanzo, S. Covino, D. Fugazza (INAF-OAB) on behalf of the REM team, report:

We observed the field of GRB 231205B (Evans et al., GCN 35269) with the REM 60cm robotic telescope located at the ESO Observatory of La Silla (Chile). The observations were carried out in the g,r,i,z, J,H,K bands, starting on 2023 Dec 06 at 00:32:29 UT (i.e. about 7.81 hours after the Swift trigger) and lasted for about 1 hour.
From preliminary analysis, we do not find any source at the enhanced XRT position (Osborne et al., GCN 35275), down the the following 3 sigma upper limits:

r > 20.4 (AB; calibrated against the Pan-STARRS catalogue)
at a mid time of t-t0 ~ 8.54 h after the GRB trigger;

H > 17.8 (Vega; calibrated against the 2MASS catalogue)
at a mid time of t-t0 ~ 8.24 h after the GRB trigger.


GRB_name: GRB231205B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35291
SUBJECT: GRB 231205B: Swift-XRT refined Analysis
DATE:    23/12/06 15:26:36 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

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

We have analysed 6.5 ks of XRT data for GRB 231205B, from 224 s to 68.4
ks after the  BAT trigger. The data comprise 3 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 an initial power-law decay with an
index of alpha=0.27 (+0.04, -0.05), followed by a break at T+6137 s to
an alpha of 1.32 (+/-0.08).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.06 (+/-0.10). The
best-fitting absorption column is  4.5 (+/-0.5) x 10^21 cm^-2, in
excess of the Galactic value of 1.5 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 3.8 x 10^-11 (6.2 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      4.5 (+/-0.5) x 10^21 cm^-2
Galactic foreground: 1.5 x 10^21 cm^-2
Excess significance: 9.6 sigma
Photon index:      2.06 (+/-0.10)

If the light curve continues to decay with a power-law decay index of
1.32, the count rate at T+24 hours will be 0.063 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.3 x
10^-12 (3.9 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/01200812.

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


GRB_name: GRB231205B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35292
SUBJECT: GRB 231205B: Ondrejov D50 optical upper limit
DATE:    23/12/06 18:45:19 GMT
FROM:    Martin Jelinek at Astro.Inst-AVCR,Ondrejov <martin.jelinek@asu.cas.cz>

Alzbeta Malenakova, Martin Jelinek, Jan Strobl,  Rene Hudec,
Cyril Polasek (ASU CAS Ondrejov, CZ),
and Sergey Karpov (Institute of Physics, Prague, CZ)

report:

The 50 cm robotic telescope D50 located at Ondrejov
observatory (Czech Republic) reacted robotically to the
Swift-BAT alert of GRB 231205B (Evans et al., GCNC 35269),
reported also by GECAM-B (Liu et al., GCNC 35279), obtaining a
series of 20 s unfiltered images starting at 16:45:46 UT, i.e.
107 s post trigger.

We do not detect any new optical source in the XRT error box
(neither any new or strongly variable source in the BAT
errorbox) in single images (detection limit r' > 18.7) nor in
a combined 30 x 20 s frame (mean exp time 290 s post trigger,
with a limit r' > 21.0) similarly to Odeh et al. (GCNC 35270),
Jiang et al.  (GCNC 35280), Jiang et al. (GCNC 35281) and
Komesh et al. (GCNC 35287).  All magnitudes are calibrated
with Atlas Refcat 2.0 (Tonry et al., ApJ 867, 105, 2018).


GRB_name: GRB231206B
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35293
SUBJECT: GRB 231206B: Fermi GBM Final Real-time Localization
DATE:    23/12/06 19:07:09 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 18:56:37 UT on 6 Dec 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231206B (trigger 723581802.598578 / 231206789).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 41.9, Dec = 3.9 (J2000 degrees, equivalent to J2000 02h 47m, 3d 53'), with a statistical uncertainty of 8.3 degrees.

The angle from the Fermi LAT boresight is 108.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231206789/quicklook/glg_skymap_all_bn231206789.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/bn231206789/quicklook/glg_healpix_all_bn231206789.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231206789/quicklook/glg_lc_medres34_bn231206789.gif


GRB_name: GRB231205B
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35295
SUBJECT: GRB 231205B: AGILE detection
DATE:    23/12/06 21:37:52 GMT
FROM:    Claudio Casentini at INAF-IAPS <claudio.casentini@inaf.it>

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

The AGILE satellite detected the GRB 231205B at T0 =  2023-12-05 16:43:59 s (UTC), reported by Swift (GCNs #35269, #35275, #35291) and GECAM-B (GCN #35279).

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 18 s and it released a total number of 11057 counts in the MCAL detector (above a background rate of 539 Hz) and 54466 counts in the AC-Top detector (above a background rate of 2889 Hz).

In the scientific ratemeters of the AC-Top detector is visible a GRB precursor,  centered around -25 s to the Swift T0 and lasting 10 seconds.

The AGILE ratemeters light curves can be found at: http://www.agilescienceapp.it/notices/GRB231205B_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: GRB231115A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35296
SUBJECT: GRB231115A: TURBO Pre-Burst Optical Upper Limits
DATE:    23/12/06 21:42:43 GMT
FROM:    Robert Strausbaugh at Eastern Illinois University <rstrausbaugh@eiu.edu>

R. Strausbaugh (Eastern Illinois University), Daniel Warshofsky (UMN), Pat Kelly (UMN), Mandeep S. S. Gill (UMN), Alexandre Toscano (UMN), Yilin Lu(UMN), Sydney Leggio (UMN), Aksinya Kamenshikova (UMN) report on behalf of a larger collaboration:


We observed M82, including the localization region for the Fermi GRB 231115A (Fermi GBM team, GCN 35035), with the Total-Coverage Ultrafast Response to Binary-Mergers Observatory (TURBO) prototype telescope in St. Paul, Minnesota, USA, as part of a high-cadence ongoing survey for transients in nearby galaxies.  We visited the field 55 times on November 15 UT, with the last visit occurring at 9:06 UT in SDSS r and g bands respectively (corresponding to 6.5 hours before the GRB trigger time).


Each exposure is 30 seconds.  We do not detect a source at the same location as the GROWTH-India counterpart (Kumar et al., GCN 35041) in either band.


The 3-sigma upper limits in the table below are calculated using the Pan-STARRS catalog as reference, and are not corrected for Galactic extinction.


The TURBO prototype in St. Paul consists of two co-mounted 11-inch telescopes each with a 6.6 square degree field of view.


TURBO, which is under construction, will consist of two arrays of 8 pairs of co-mounted 11-inch telescopes at two dark-sky sites: Magdalena Ridge Observatory, New Mexico, USA and Skinakas Observatory, Crete, Greece.


mjd

g upper limit (AB)

r upper limit (AB)

60262.97035880

-

16.0

60262.97244213

16.9

-

60263.00063657408


-

15.9

60263.00407407407

-

15.7

60263.007106481484

-

16.1

60263.012094907404

-

15.6

60263.015555555554

-

15.9

60263.01940972222

-

16.0

60263.02327546296

-

15.9

60263.02715277778

-

16.3

60263.03057870371

-

16.1

60263.034212962964

-

16.1

60263.03765046296

-

16.4

60263.04111111111

-

15.7

60263.04293981481

-

15.8

60263.04591435185

16.5

15.7

60263.04896990741

-

16.4

60263.05202546297

16.5

15.8

60263.055

16.5

15.6

60263.058020833334

-

15.8

60263.061006944445

-

16.0

60263.06407407407

-

15.9

60263.070497685185

-

16.3

60263.07403935185

-

16.2

60263.07748842592

-

15.8

60263.080462962964

-

16.3

60263.08472222222

-

16.1

60263.087592592594

16.5

16.4

60263.09365740741

16.4

16.3

60263.09645833333

15.9

16.5

60263.099375

-

16.4

60263.1171412037

-

16.7

60263.120150462964

16.3

16.3

60263.12315972222

-

15.4

60263.14434027778

16.6

15.6

60263.14716435185

16.0

15.7

60263.15039351852

15.7

16.1

60263.15372685185

16.5

16.0

60263.156539351854

15.8

16.0

60263.159421296295

16.0

16.3

60263.162314814814

16.6

15.8

60263.165138888886

15.8

16.8

60263.16957175926

16.3

16.2

60263.172997685186

16.4

-

60263.176516203705

16.5

16.5

60263.19818287037

16.8

15.8

60263.21885416667

16.9

16.8

60263.22230324074

17.4

17.0

60263.24633101852

17.3

16.4

60263.268900462965

17.3

16.6

60263.27537037037

16.9

16.9

60263.27885416667

17.3

17.0

60263.283229166664

17.0

16.9

60263.28666666667

16.9

17.0

60263.29603009259

17.4

16.8


GRB_name: GRB231205B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35299
SUBJECT: GRB 231205B: optical upper limit in TSHAOand AbAO
DATE:    23/12/07 04:13:53 GMT
FROM:    Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>

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

We observed the field of GRB 231205B (Evans et al, GCN 35269; Liu & Xiong, GCN 35279) with Zeiss-1000 telescope of Tien-Shan Observatory (TSHAO), and AS-32 telescope of Abastumani Observatory (AbAO). No new optical sources have been found at the enhanced XRT position (Osborne et al, GCN 35275) in our observations, which is consistent with results reported early (Odeh et al, GCN 35270; Strausbaugh & Cucchiara, GCN 35278; Jiang et al, GCN 35280; Jiang et al, GCN 35281; Gendre et al, GCN 35282; Sasada et al, GCN 35284; Adami et al, GCN 35286; Komesh et al, GCN 35287; Brivio et al, GCN 35289;  Malenakova et al, GCN 35292). Preliminary photometry is following:

Date       UT start  t-T0     Exp.   Filter  OT Err.    UL  Telescope
                   (mid, days)  (s)                    (3sigma) 
2023-12-05 16:43:59  0.0208333 30x120  R   n/d    n/d  22.0  Zeiss-10000
2023-12-05 17:16:09  0.0315857 59x60   R   n/d    n/d  19.6  AS-32


GRB_name: GRB231206A
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35300
SUBJECT: GRB 231206A: joint location of multiple instruments by ETJASMIN
DATE:    23/12/07 06:18:14 GMT
FROM:    yqzhang_cl@163.com

Yanting Zhang, Shaolin Xiong, Yue Huang, Shuo Xiao, Xiaoyun Zhao, Ping Wang, 
report on behalf of the GECAM team:

The short burst, GRB 231206A, has been detected by GECAM-B (Liu et al., GCN 35283) and INTEGRAL/SPI-ACS. 
With the ETJASMIN pipeline (Energetic Transients joint analysis system for Multi-INstrument, Xiao et al.,
MNRAS, 514, 2397, 2022) and the data of GECAM-B and INTEGRAL/SPI-ACS, we did a joint location for this burst.

Firstly, we applied the Li-CCF method (Xiao et al., ApJ, 920, 43, 2021) to the high 
temporal resolution (~0.1 ms) light curve of GECAM-B and the low-latency public 50 ms 
light curve of INTEGRAL/SPI-ACS, and derived the triangulation location as the following annuli:

--------------------------------------------------------------------------------------------------
Annulus                 Ra (deg)      Dec (deg)     Radius (deg)      Radius-Error (deg, 3sigma)
GECAM-B + SPI-ACS       37.933        78.224        103.958           47.522
--------------------------------------------------------------------------------------------------

Then, we combined this triangulation location, the stand-alone location provided by GECAM-B 
(Liu et al., GCN 35283), as well as the Earth occultation of these instruments, 
and derived a refined location, which is much smaller than the stand-alone ones. 

The center (highest probability) of this refined location is:

--------------------------------------
            RA (deg)      Dec (deg)
Center      314.648   -20.742   
--------------------------------------

The 1-simga region of this refined location is about 295 deg^2. 

The sky map and probability healpix data of this refined location could be found at:
Sky map: http://twiki.ihep.ac.cn/pub/GECAM/GRBList/GRB231206-jointLoc-skymap-v01.png
Data file: http://twiki.ihep.ac.cn/pub/GECAM/GRBList/GRB231206A-jointLoc-healpix-v01.fits

Note that a part of the location region is below the Earth limb of GECAM-B and thus excluded.

This location may be improved.

ETJASMIN is developed for joint observation of high energy transients by the GECAM team.
We acknowledge the public data of INTEGRAL/SPI-ACS. 


GRB_name: GRB231205B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35302
SUBJECT: GRB 231205B: 1.3m DFOT Optical upper limit
DATE:    23/12/07 13:20:11 GMT
FROM:    Amit Kumar Ror at ARIES <mitturor77894@gmail.com>

Amit K. Ror, Rahul Gupta, Amar Aryan, and Shashi B. Pandey (ARIES) report:

We observed the field of GRB 231205B detected by Swift (Evans et al. 2023,
GCN 35269) with the 1.3m Devasthal Fast Optical Telescope (DFOT), located
at the Devasthal Observatory of the Aryabhatta Research Institute of
Observational Sciences (ARIES), India. The observations were started on
2023-12-06 at 13:19:13 UT, i.e., ~ 0.86 days after the BAT trigger. We have
taken multiple frames with an exposure time of 300 s in the R filter. We
stacked the images after the alignment. We did not detect optical afterglow
in our stacked image within the enhanced Swift-XRT observation error box
(Osborne et al., 2023, GCN 35275). We obtain the following preliminary
3-sigma upper limit in the stacked image:


Date Start_UT T_start-T0 (days) Filter  Exp time (s)  Limiting magnitude
=========================================================
2023-12-06 13:19:13    ~0.86     R     300*36     > 22.6


Our non-detection is consistent with Odeh et al. 2023, GCN 35270;
Strausbaugh et al. 2023, GCN 35278; Jiang et al. 2023, GCN 35280; Jiang et
al. 2023, GCN 35281; Gendre et al. 2023, GCN 35282; Sasada et al. 2023, GCN
35284; Adami et al. 2023, GCN 35286; Komesh et al. 2023, GCN 35287; Brivio
et al. 2023, GCN 35289; Malenakova et al. 2023, GCN 35292; and Pankov et
al. 2023, GCN 35299

The magnitude is not corrected for the Galactic extinction in the direction
of the burst. Photometric calibration is performed using the standard stars
from the USNO-B1.0 catalog. This circular may be cited.


GRB_name: GRB231205B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35303
SUBJECT: GRB 231205B: Swift-BAT refined analysis
DATE:    23/12/07 14:01:00 GMT
FROM:    Tyler Parsotan  at NASA GSFC <tyler.parsotan@nasa.gov>

T. Parsotan (GSFC), 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-60 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 231205B (trigger #1200812)
(Evans, et al., GCN Circ. 35269). The BAT ground-calculated position is
RA, Dec = 54.151, 27.150 deg which is
RA(J2000) = 03h 36m 36.3s
Dec(J2000) = +27d 09' 00.7"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 50%.

The mask-weighted light curve shows a strong peak near the time of trigger.
There is also emission prior to the main peak of the lightcurve at ~T-30 sec.
T90 (15-350 keV) is 46.94 +- 7.84 sec (estimated error including systematics).

The time-averaged spectrum from T-29.66 to T+54.16 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.38 +- 0.05. The fluence in the 15-150 keV band is 7.4 +- 0.2 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T-5.04 sec in the 15-150 keV band
is 7.1 +- 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/1200812/BA/ <http://gcn.gsfc.nasa.gov/notices_s/1200812/BA/> <http://gcn.gsfc.nasa.gov/notices_s/1200812/BA/> <http://gcn.gsfc.nasa.gov/notices_s/1200812/BA/&gt;>


GRB_name: GRB231205A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35304
SUBJECT: IPN triangulation of GRB 231205A
DATE:    23/12/07 16:20:39 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.-L. Xiong, Y. Huang, X.-Y. Zhao, and P. Wang
on behalf of the GECAM 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 bright, short-duration GRB 231205A
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 35263;
GECAM-B detection: Tan et al., GCN Circ. 35266;
ETJASMIN localization: Zhang et al., GCN Circ. 35268)
has been detected by Fermi-GBM (trigger 723435916), Konus-Wind,
INTEGRAL (SPI-ACS), GECAM-B (GRD), and Mars-Odyssey (HEND)
so far, at about  8711 s UT (02:25:11).

We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
 ---------------------------------------------
  RA(2000), deg                 Dec(2000), deg
 ---------------------------------------------
 Center:
  202.936 (13h 31m 45s) +17.932 (+17d 55' 55")
 Corners:
  203.258 (13h 33m 02s) +18.299 (+18d 17' 58")
  202.683 (13h 30m 44s) +17.694 (+17d 41' 38")
  202.612 (13h 30m 27s) +17.557 (+17d 33' 25")
  203.188 (13h 32m 45s) +18.166 (+18d 09' 57")
 ---------------------------------------------
The error box area is 119 sq. arcmin, and its maximum
dimension is 58 arcmin (the minimum one is 2.4 arcmin).
The Sun distance was 62 deg.

This localization may be improved.

The IPN localization is consistent with, but reduces the area of,
the Fermi-GBM final localization and ETJASMIN localization.

A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB231205_T08710/IPN

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


GRB_name: GRB231208A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35306
SUBJECT: GRB 231208A: AstroSat CZTI detection of a faint burst
DATE:    23/12/08 10:08:59 GMT
FROM:    Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>

P. K. Navaneeth (IUCAA), J. Joshi (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 faint long-duration GRB 231208A.

The source was detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2023-12-08 02:29:47.75 UTC. The measured peak count rate associated with the burst is 146 (+47, -32) counts/s above the background in the combined data of three quadrants (out of four), with a total of 231 (+88, -106) counts. The local mean background count rate was 265 (+3, -5) counts/s. Using cumulative rates, we measure a T90 of 2.4 (+0.7, -1.2) s. 

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: GRB231208A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35307
SUBJECT: GRB 231208A: Glowbug gamma-ray detection
DATE:    23/12/08 16:59:19 GMT
FROM:    C.C. Cheung at Naval Research Lab <Teddy.Cheung@nrl.navy.mil>

C.C. Cheung, M. Kerr, J. E. Grove, R. Woolf (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge (MSFC), and M.S. Briggs (UAH) report:                                                                                                                                                                                                                                                    

The Glowbug gamma-ray telescope [1,2], operating on the International Space Station, reports the detection of GRB 231208A, which was also detected by Astrosat/CZTI (GCN 35306).

Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2023-12-08 02:29:43.384 with a duration of 5.1 s and a total significance of about 38 sigma.  The light curve comprises two primary peaks at ~T0+2s and ~T0+3s.

Using a standard power-law function with an exponential high-energy cutoff [3] to model the emission over this duration results in a photon index dN/dE~E^x of x=2.5 and a cutoff energy ("Epeak") of 136 keV.  The modeled 10-10000 keV fluence is 9.1e-07 erg/cm^2.

The best-fit localization is RA, Decl. (J2000, deg) = 339.7, 21.2 with a radius of 14.8 deg (95% confidence) with a highly uncertain systematic uncertainty.

The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.

Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC.  It was launched on 2023 March 15 aboard the Department of Defense Space Test Programâ€™s STP-H9 to the ISS.  The detector comprises 12 large-area (15 cm x 15 cm) CsI:Tl panels covering the surface of a half cube, and two hexagonal (5-cm diameter, 10-cm length) CLLB scintillators, giving it a large field of view (instantaneous FoV ~2/3 sky) over a wide energy band of 50 keV to >2 MeV.

[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959
[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O
[3] Goldstein, A. et al. 2020, ApJ 895, 40, arXiv :1909.03006

Distribution Statement A: Approved for public release.  Distribution is unlimited.


GRB_name: GRB231205B
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35308
SUBJECT: GRB231205B: Swift/UVOT Upper Limits
DATE:    23/12/08 17:38:53 GMT
FROM:    Mike Siegel at PSU/Swift MOC <mhs18@psu.edu>

M. H. Siegel (PSU) and P. A. Evans (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 231205B
216 s after the BAT trigger (Evans et al., GCN Circ. 35269).
No optical afterglow consistent with the XRT position
(Osborne et al. 35275) 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           237          387          147         >21.3
white              237          536          167         >21.3
v                  216          414           33         >18.6
b                  492          512           19         >19.6
u                  468          487           19         >18.2
w1                 443          463           19         >19.3

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.204 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB231208A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35309
SUBJECT: GRB 231208A: GRBAlpha detection
DATE:    23/12/10 10:53:52 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, L. Szakszonova, 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 231208A (AstroSat detection: GCN 35306; Glowbug detection: GCN 35307; Konus/Wind trigger at 2023-12-08 02:29:45.527 UT) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; arXiv:2302.10048).

The detection was confirmed at the peak time 2023-12-08 02:29:46 UTC. The T90 duration measured by GRBAlpha is 3 s and the overall significance during T90 reaches 5 sigma.

The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB231208A_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: GRB231210A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35310
SUBJECT: GRB 231210A: Fermi GBM Final Real-time Localization
DATE:    23/12/10 13:26:23 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 13:15:50 UT on 10 Dec 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231210A (trigger 723906955.510584 / 231210553).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 137.9, Dec = 10.3 (J2000 degrees, equivalent to J2000 09h 11m, 10d 18'), with a statistical uncertainty of 14.4 degrees.

The angle from the Fermi LAT boresight is 44.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231210553/quicklook/glg_skymap_all_bn231210553.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/bn231210553/quicklook/glg_healpix_all_bn231210553.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231210553/quicklook/glg_lc_medres34_bn231210553.gif


GRB_name: GRB231129C
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35311
SUBJECT: IPN triangulation of GRB 231129C
DATE:    23/12/10 19:03:56 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 and HEND/Mars Odyssey teams,

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,

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 very bright, long-duration GRB 231129C
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 35217;
Sharma et al., GCN Circ. 35221, 35227;
BALROG localization: Preis et al., GCN Circ. 35222;
MAXI-GSC detection: Kawakubo et al., GCN Circ. 35223;
CALET-CGBM detection: Shimizu et al., GCN Circ. 35228;
AstroSat-CZTI detection: Waratkar et al., GCN Circ. 35230;
GECAM-B detection: Zheng and Xiong, GCN Circ. 35231;
Glowbug detection: Cheung et al., GCN Circ. 35235;
GRBAlpha detection: Dafcikova et al., GCN Circ. 35236;
Fermi-LAT detection: Arimoto et al., GCN Circ. 35238;
Swift-BAT/GUANO detection: DeLaunay et al., GCN Circ. 35242;
AGILE detection: Panebianco et al., GCN Circ. 35244;
Konus-Wind detection: Lysenko et al., GCN Circ. 35256;
ASIM-MXGS detection: Marisaldi et al., GCN Circ. 35288)
was detected by Fermi (GBM, LAT), ISS (Glowbug, CALET-CGBM),
AstroSat (CZTI), GECAM-B (GRD), GRBAlpha, AGILE (MCAL, AC),
Swift (BAT), Konus-Wind, INTEGRAL (SPI-ACS),
GRBAlpha, Mars-Odyssey (HEND), and BebiColombo (MGNS)
at about 69018 s UT (19:10:18).
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:
    9.975 (00h 39m 54s) -81.812 (-81d 48' 43")
 Corners:
    4.821 (00h 19m 17s) -80.799 (-80d 47' 56")
   16.263 (01h 05m 03s) -82.675 (-82d 40' 29")
   16.443 (01h 05m 46s) -82.746 (-82d 44' 45")
    4.881 (00h 19m 31s) -80.873 (-80d 52' 23")
 ---------------------------------------------
The error box area is 322 sq. arcmin, and its maximum
dimension is 2.5 deg (the minimum one is 2.2 arcmin).
The Sun distance was 73 deg.

This localization may be improved.

The IPN localization is consistent with, but reduces the area of,
the Fermi-GBM/LAT and ASIM localizations.

The Swift-XRT reported Source 2 (GCN 35234, 35251) is inside the IPN box, supporting that the source is the afterglow of GRB 231129C.

A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB231129_T69016/IPN/


GRB_name: GRB231210B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35314
SUBJECT: GRB 231210B: Swift detection of a burst with optical counterpart
DATE:    23/12/10 21:49:47 GMT
FROM:    Jamie Kennea at Penn State <jak51@psu.edu>


K. L. Page (U Leicester), J.D. Gropp (PSU), J. A. Kennea (PSU),
D. M. Palmer (LANL), T. M. Parsotan (GSFC/UMBC/CRESSTII) and
M. A. Williams (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 21:29:04 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 231210B (trigger=1201696).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 95.772, -48.359 which is 
   RA(J2000) = 06h 23m 05s
   Dec(J2000) = -48d 21' 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 15 sec.  However, since this
GRB occurred while the spacecraft was leaving the SAA, the rate
lightcurve is hard to interpret.  The peak count rate
was ~1500 counts/sec (15-350 keV), at ~T+0 sec after the trigger. 

The XRT began observing the field at 21:31:07.8 UT, 123.4 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source with an enhanced position: RA, Dec 95.79386,
-48.37201 which is equivalent to:
   RA(J2000)  = 06h 23m 10.53s
   Dec(J2000) = -48d 22' 19.2"
with an uncertainty of 1.9 arcseconds (radius, 90% containment). This
location is 70 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. 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 4.31e-10 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 462 seconds after the BAT trigger. Due to tracking issues, the 
UVOT image is blurred. However, comparison with DSS shows that there appears
to be a new source coincident with the XRT localization. Further data and 
analysis will be needed to report an accurate localization and magnitude 
of this object. 

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: GRB231210B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35316
SUBJECT: GRB 231210B: detection of the optical counterpart with the LCOGT 40cm telescope at Sutherland Observatory
DATE:    23/12/11 01:12:12 GMT
FROM:    Ismael Perez-Fournon at Instituto de Astrofisica de Canarias <ipf@iac.es>

I. PÃ©rez-Fournon, F. Poidevin (IAC and ULL), H. Akoudad-Ekajouan, C. Araujo-Ãlvarez, C. Arrizabalaga-DÃ­az-Caneja, F. Barnes-SÃ¡nchez, P. Eguiguren-Arrizabalaga, A. Iglesias-LÃ³pez, G.A. Jaimes-Illanes, P. JimÃ©nez-SÃ¡nchez, S. Lamolda-Mir, A. Mang-RomÃ¡n, G. Marrero-Ramallo, P.P. Meni-Gallardo, I. Ruiz-Cejudo (ULL), M. SÃ¡nchez-AndÃºjar (ULL and IAC), V. Wienzek (ULL), E. Esparza-Borges, and F. Tinaut-Ruano (IAC and ULL)

report observations of GRB 231210B with the LCOGT 40cm telescope at Sutherland Observatory starting on 2023-12-10 22:22:25 UT in the SDSS g', r', and i' filters.

We detect a source in the three filters at the position RA (J2000) = 06h 23m 10.997s,  Dec (J2000) = -48d 22m 19.87s, that is close to the Swift position reported by Page et al. (GCN 35314) and the optical transient reported by Buckley et al. (GCN 35313).

We measure the following magnitudes:

  Date      Time        Filter    Exposure (sec)            Mag      Error
---------------------|-----------|---------------------|------------|-------
2023-12-10 22:22:25     g          180                       20.72     0.18 
2023-12-10 22:25:34     r          180                       19.69     0.12
2023-12-10 22:28:42     i          180                       19.62     0.26


GRB_name: GRB231210B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35317
SUBJECT: GRB 231210B: VLT/X-shooter redshift
DATE:    23/12/11 04:42:22 GMT
FROM:    Andrea Saccardi at Observatoire de Paris <andrea.saccardi@obspm.fr>

A. Saccardi (GEPI, Observatoire de Paris), B. Schneider (MIT), L. Izzo (INAF-Naples & DARK/NBI), D. B. Malesani (DAWN/NBI), C. PeÃ±a (Univ. of Utah) report on behalf of the Stargate collaboration:

We observed the field of the Swift GRB 231210B (Page et al., GCN 35314) using the ESO/VLT/UT3 (Melipal) equipped with the X-shooter spectrograph. Our spectra cover the wavelength range 3000-21000 AA, and consist of 4 exposures of 600s each. The observation starting-time is 01:32:26 UT on Dec 11 2023 (~4 hr after the Swift trigger).

In images taken with the acquisition camera, we clearly detect the optical afterglow consistent with the position reported by Buckley et al., GCN 35313 and PÃ©rez-Fournon et al., GCN 35316. We measure the following AB magnitudes (calibrated against SkyMapper stars): g' = 21.82 +/- 0.05 mag, r' = 21.23 +/- 0.04 mag, z' = 21.03 +/- 0.07 mag.

We detect a continuum over the entire wavelength range. From the detection of a broad Lya absorption at ~5000 AA and multiple absorption features, which we interpret as being due to NV, SiII, SII, OI, CII, ZnII, FeII, AlII, CIV, SiIV, FeII*, OI*, SiII*, CII*, we infer a common redshift of z = 3.13. We conclude this is the redshift of the burst. We also note the presence of additional absorption features likely due to multiple intervening systems.

We acknowledge the excellent support from the ESO staff in Paranal, in particular Maria Jose Rain, Zahed Wahhaj and Thomas Seifert.


GRB_name: GRB231210B
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35318
SUBJECT: GRB 231210B: Enhanced Swift-XRT position
DATE:    23/12/11 07:16:25 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 1563 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 231210B, 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 = 95.79470, -48.37226 which is equivalent
to:

RA (J2000): 06h 23m 10.73s
Dec (J2000): -48d 22' 20.2"

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: GRB231210B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35319
SUBJECT: GRB 231210B: Swift-XRT refined Analysis
DATE:    23/12/11 10:23:58 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

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),
J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), D.N. Burrows (PSU) and
P.A. Evans report on behalf of the Swift-XRT team:

We have analysed 6.4 ks of XRT data for GRB 231210B, from 410 s to 35.6
ks after the  BAT trigger. The data comprise 40 s in Windowed Timing
(WT) mode 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=1.32 (+0.05, -0.04).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.65 (+0.11, -0.10). The
best-fitting absorption column is  5.3 (+7.7, -5.3) x 10^21 cm^-2, at a
redshift of 3.13, in addition to the Galactic value of 4.1 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 4.0 x
10^-11 (4.3 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Galactic foreground: 4.1 x 10^20 cm^-2
Intrinsic column:    5.3 (+7.7, -5.3) x 10^21 cm^-2 at z=3.13
Photon index:      1.65 (+0.11, -0.10)

If the light curve continues to decay with a power-law decay index of
1.32, the count rate at T+24 hours will be 4.5 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.8 x
10^-13 (1.9 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/01201696.

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


GRB_name: GRB231210B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35322
SUBJECT: GRB 231210B: Swift-BAT refined analysis
DATE:    23/12/11 21:10:59 GMT
FROM:    Mike Moss at NASA GSFC <mikejmoss3@gmail.com>

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), K. L. Page (U Leicester)
T. Parsotan (GSFC/UMBC), M. Stamatikos (OSU)
(i.e. the Swift-BAT team):
 
Using the data set from T-36 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 231210B (trigger #1201696)
(Page, et al., GCN Circ. 35314).  The BAT ground-calculated position is
RA, Dec = 95.803, -48.335 deg which is
   RA(J2000)  =  06h 23m 12.7s
   Dec(J2000) = -48d 20' 04.6"
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 17%.
 
The mask-weighted light curve shows a FRED pulse potentially followed by a dimmer spike.
T90 (15-350 keV) is 7.47 +- 0.65 sec (estimated error including systematics).
 
The time-averaged spectrum from T-0.23 to T+7.82 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.08 +- 0.19.  The fluence in the 15-150 keV band is 1.4 +- 0.2 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T-0.24 sec in the 15-150 keV band
is 3.9 +- 0.7 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/1201696/BA/


GRB_name: GRB231210B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35323
SUBJECT: GRB 231210B: MeerLICHT afterglow observations
DATE:    23/12/11 21:11:37 GMT
FROM:    Simon de Wet at University of Cape Town <simdewet@gmail.com>

S. de Wet (UCT), P.M. Vreeswijk (Radboud) and P.J. Groot (Radboud/UCT/SAAO) report on behalf of the MeerLICHT consortium:

The 0.6 m wide-field MeerLICHT optical telescope located in Sutherland, South Africa, obtained a repeated series of 60 s exposures in the q,u,g,r,i,z bands of GRB 231210B following the Swift detection (Page et al., GCN 35314). Observations started at 21:32:26 UT on 2023 November 18 (202 seconds post-trigger) and continued for a further 1.79 hours, following the filter sequence quqgqrqiqz. 

We detect the optical afterglow also detected by MASTER, UVOT, LCOGT, and the VLT (Buckley et al., GCN 35313; Page et al., GCN 35314; PÃ©rez-Fournon et al., GCN 35316; Saccardi et al., GCN 35317) with the following AB magnitudes:

q = 17.15 +/- 0.02 at 21:32:57 UT
u = 19.67 +/- 0.19 at 21:34:20 UT
g = 18.69 +/- 0.04 at 21:37:17 UT
r = 18.11 +/- 0.03 at 21:40:11 UT
i = 18.15 +/- 0.05 at 21:43:08 UT
z = 18.30 +/- 0.11 at 21:46:05 UT

As a precaution, we note that the absolute photometric calibration may have been adversely affected by condensation in the cryostat window due to high humidity. Our high cadence q-band observations show a power-law decline with a temporal index of -1.2 throughout the observations. 

MeerLICHT is built and run by a consortium consisting of Radboud University, University of Cape Town, the South African Astronomical Observatory, the University of Oxford, the University of Manchester and the University of Amsterdam. 


GRB_name: GRB231212A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35325
SUBJECT: GRB 231212A: GECAM-C detection of a likely short burst 
DATE:    23/12/12 03:35:22 GMT
FROM:    Yue Wang <m18509381757@163.com>

Yue Wang, Shao-Lin Xiong report on behalf of the GECAM team:

GECAM-C was triggered in-flight by a likely short burst, GRB 231212A, at 2023-12-12T00:56:48.850 UTC (T0), which was also triggered by Fermi/GBM (TrigNum724035412) . 

According to the realtime alert data, the GECAM-C light curve shows a short pulse with a duration of ~4 sec (15-1050 keV). 

The time-averaged spectrum of GECAM-C realtime data from about T0-2 s to T0+2 s could be
adequately fit by a cut-off power-law with a flux about 8.01E-7 erg/cm^2/s in 20-1000 keV.

Using the automatic on-ground localization pipeline with the realtime alert data, 
GECAM-C localized this burst to the following position (J2000): 
Ra:  151.1 deg 
Dec: -74.1 deg
Err: 7.1 deg (1-sigma, statistical only)

The GECAM light curve and localization could be found here: 
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/231212A_lc.jpg
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/231212A_loc.png

We note that these results are based on realtime alert data and thus very preliminary. 

Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor(GECAM) mission originally consists of two microsatellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS).


GRB_name: GRB231210B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35333
SUBJECT: GRB 231210B: REM optical/NIR upper limits
DATE:    23/12/14 12:04:18 GMT
FROM:    Matteo Ferro <matteo.ferro@inaf.it>

M. Ferro, R. Brivio, P. D'Avanzo, S. Covino, D. Fugazza (INAF-OAB) on behalf of the REM team, report:

We observed the field of GRB 231210B (Page et al., GCN 35314) with the REM 60cm robotic telescope located at the ESO Observatory of La Silla (Chile). The observations were carried out in the g,r,i,z, J,H,K bands, starting on 2023 Dec 11 at 00:36:37 UT (i.e. about 3.13 hours after the Swift trigger) and lasted for about 1 hour.
From preliminary analysis, we do not find any source at the enhanced XRT position (Beardmore et al., GCN 35318), down the the following 3 sigma upper limits:

r > 21.0 (AB; calibrated against the SkyMapper catalogue)
at a mid time of t-t0 ~ 3.80 h after the GRB trigger;

H > 17.4 (Vega; calibrated against the 2MASS catalogue)
at a mid time of t-t0 ~ 3.56 h after the GRB trigger.


GRB_name: GRB231214A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35334
SUBJECT: GRB 231214A: Fermi GBM Final Real-time Localization
DATE:    23/12/14 20:34:47 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 20:24:24 UT on 14 Dec 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231214A (trigger 724278269.684604 / 231214850).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 302.2, Dec = -72.1 (J2000 degrees, equivalent to J2000 20h 08m, -72d 05'), with a statistical uncertainty of 1.0 degrees.

The angle from the Fermi LAT boresight is 50.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231214850/quicklook/glg_skymap_all_bn231214850.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/bn231214850/quicklook/glg_healpix_all_bn231214850.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231214850/quicklook/glg_lc_medres34_bn231214850.gif


GRB_name: GRB231214A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35335
SUBJECT: GRB 231214A: Swift detection of a burst
DATE:    23/12/14 20:38:57 GMT
FROM:    K.L. Page at U Leicester <klp5@leicester.ac.uk>


R. Brivio (INAF-OAB), P. D'Avanzo (INAF-OAB), S. Dichiara (PSU),
M. Ferro (INAF-OAB), M. J. Moss (GSFC), K. L. Page (U Leicester),
D. M. Palmer (LANL), C. Salvaggio (INAF-OAB) and M. A. Williams (PSU)
report on behalf of the Neil Gehrels Swift Observatory Team:

At 20:24:28 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 231214A (trigger=1202386).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 305.736, -72.436 which is 
   RA(J2000) = 20h 22m 57s
   Dec(J2000) = -72d 26' 09"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a double-peaked
structure with a duration of about 30 sec.  The peak count rate
was ~8000 counts/sec (15-350 keV), at ~13 sec after the trigger. 

The XRT began observing the field at 20:26:14.5 UT, 106.2 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 305.68573, -72.43256
which is equivalent to:
   RA(J2000)  = 20h 22m 44.58s
   Dec(J2000) = -72d 25' 57.2"
with an uncertainty of 1.9 arcseconds (radius, 90% containment). This
location is 56 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. No
spectrum from the promptly downlinked event data is yet available to
determine the column density. 

UVOT took a finding chart exposure of  39 seconds with the White filter
starting 442 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
0.060. 

Burst Advocate for this burst is R. Brivio (riccardo.brivio 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: GRB231214A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35339
SUBJECT: GRB231214A: BOOTES-6/DPRT optical upper limit
DATE:    23/12/14 21:35:30 GMT
FROM:    Youdong HU at IAA-CSIC <huyoudong072@hotmail.com>

Y.-D. Hu, E. Fernandez-Garcia, I. Perez-Garcia, M.D. Caballero-Garcia, R. Sanchez-Ramirez, S. Guziy, S.-Y. Wu and A. J. Castro-Tirado (IAA-CSIC, Granada), P. J. Meintjes and H. J. van Heerden (UFS, South Africa), A. Martin-Carrillo and L. Hanlon (UCD, Ireland) and C. J. Perez del Pulgar (UMA, Malaga), on behalf of a larger collaboration, report:

Following the detection of GRB 231214A by Swift (Brivio et al. GCNC 35335) and Fermi (Fermi GBM team GCNC 35334), the BOOTES-6/DPRT 0.6m robotic telescope at Boyden Observatory in Maselspoort (South Africa) automatically observed the GRB location starting on Dec. 14, 20:42 UT (~ 18 min after trigger). No new optical source is detected on the co-added images (11 x 10 s, clear-filter) within the Swift/XRT error region down to 19.1 mag, which is consistent with both reports from UVOT (Brivio et al. GCNC 35335) and MASTER (Lipunov et al. GCNC 35336).

We thank the staff at Boyden Observatory for their excellent support.


GRB_name: GRB231214B
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35340
SUBJECT: GRB 231214B: Swift/BAT-GUANO detection of a burst
DATE:    23/12/14 22:38:11 GMT
FROM:    Jimmy DeLaunay at Penn State <delauj2@gmail.com>

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

Swift/BAT did not localize GRB 231214B onboard (T0: 2023-12-14T07:53:55.52 UTC, Fermi GBM Trig 724233240). 

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), performed on the temporal window [T0-20 s, T0+20 s], detects the burst with a sqrt(TS) of 8.6 in a 16.384 s analysis time bin, starting at T0 - 8.192 s. 

NITRATES results, independently, are ambiguous with respect to whether this burst originates from in or outside the BAT coded FOV, with a DeltaLLHOut of 8.2.

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: GRB231214A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35341
SUBJECT: GRB 231214A: Enhanced Swift-XRT position
DATE:    23/12/15 00:45:23 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 842 s of XRT Photon Counting mode data and 4 UVOT
images for GRB 231214A, 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 = 305.68530, -72.43283 which is equivalent
to:

RA (J2000): 20h 22m 44.47s
Dec (J2000): -72d 25' 58.2"

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: GRB231214A
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35342
SUBJECT: GRB 231214A: Fermi-LAT detection
DATE:    23/12/15 06:25:50 GMT
FROM:    Makoto Arimoto at Tokyo Inst of Tech <arimoto@hp.phys.titech.ac.jp>

D. Kocevski (NASA/MSFC), N. Di Lalla (Stanford University), M. Arimoto
(Kanazawa University), and T. Khalil (Johannesburg University) report
on behalf of the Fermi-LAT Collaboration:

On December 14, 2023 Fermi-LAT detected high-energy emission from GRB
231214A, which was also detected by Fermi-GBM (trigger
724278269.684604 / 231214850, GCN 35334), Swift-BAT and Swift-XRT (GCN
35335, 35341).

The best LAT on-ground location is found to be
RA, Dec = 306.1, -72.4 (degrees, J2000)
with an error radius of 0.2 deg (90% containment, statistical error
only). This was 51 deg from the LAT boresight at the time of the GBM
trigger: T0 = 20:24:24.69 UT.

The data from the Fermi-LAT show a significant increase in the event
rate after the GBM trigger that is spatially correlated with the GBM
emission with high significance. The photon flux above 100 MeV in the
time interval 0-3000 s after the GBM trigger is (3.9 +/- 0.8)E-6
ph/cm2/s.
The estimated photon index above 100 MeV is -1.9 +/- 0.2. The
highest-energy photon is a 2.9 GeV event which is observed 414 seconds
after the GBM trigger.
The Fermi-LAT point of contact for this burst is Tamador Khalil
(tamtam2030@gmail.com)

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: GRB231215A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35343
SUBJECT: GRB 231215A: Swift detection of a burst
DATE:    23/12/15 09:55:59 GMT
FROM:    David Palmer at LANL <palmer@lanl.gov>


P. D'Avanzo (INAF-OAB), R. Brivio (INAF-OAB), M. Ferro (INAF-OAB),
J.D. Gropp (PSU), K. L. Page (U Leicester), D. M. Palmer (LANL),
T. Sakamoto (AGU), C. Salvaggio (INAF-OAB), T. Sbarrato (INAF-OAB),
B. Sbarufatti (INAF-OAB) and M. H. Siegel (PSU) report on behalf of
the Neil Gehrels Swift Observatory Team:

At 09:47:25 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 231215A (trigger=1202522).  Swift could not immediately slew
due to an Earth limb observing constraint. 
The BAT on-board calculated location is 
RA, Dec 9.750, +57.642 which is 
   RA(J2000) = 00h 39m 00s
   Dec(J2000) = +57d 38' 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 ~6000 counts/sec (15-350 keV), at ~1 sec after the trigger. 

Due to an observing constraint, Swift will not slew until T0+42.6
minutes. There will be no XRT or UVOT data until this time. 

Burst Advocate for this burst is P. D'Avanzo (paolo.davanzo 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: GRB231215B
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35344
SUBJECT: GRB 231215B: Fermi GBM Final Real-time Localization
DATE:    23/12/15 09:57:45 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 09:47:17 UT on 15 Dec 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231215B (trigger 724326442.811262 / 231215408).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 11.1, Dec = 61.2 (J2000 degrees, equivalent to J2000 00h 44m, 61d 12'), with a statistical uncertainty of 1.0 degrees.

The angle from the Fermi LAT boresight is 114.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231215408/quicklook/glg_skymap_all_bn231215408.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/bn231215408/quicklook/glg_healpix_all_bn231215408.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231215408/quicklook/glg_lc_medres34_bn231215408.gif


GRB_name: GRB231215A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35345
SUBJECT: GRB 231215A: Swift-XRT observations
DATE:    23/12/15 11:15:35 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), D.N. Burrows
(PSU), J.A. Kennea (PSU), S. Campana (INAF-OAB) and G. Cusumano
(INAF-IASF PA) report on behalf of the Swift-XRT team:

The XRT began observing the field of GRB 231215A at 10:32:51.0 UT,
2725.7 seconds after the BAT trigger. Using promptly downlinked data we
find a bright, fading, uncatalogued X-ray source located at RA, Dec
9.74175, 57.64645 which is equivalent to:
   RA(J2000)  = 00h 38m 58.02s
   Dec(J2000) = +57d 38' 47.2"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This
location is 22 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 (4.25 x
10^21 cm^-2, Willingale et al. 2013), with an excess column of 4.7
(+2.34/-2.12) x 10^21 cm^-2 (90% confidence). 


GRB_name: GRB231215C
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35347
SUBJECT: GRB 231215C: MASTER OT detection
DATE:    23/12/15 11:42:53 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>

V.Lipunov, P.Balanutsa (Lomonosov MSU), O.Gress, N.Budnev (ISU),
E.Gorbovskoy, D.Svinkin (Ioffe Institute, Konus-Wind),
Ya.Kechin, K.Zhirkov, A.Kuznetsov, D.Vlasenko, P.Balanutsa, Yu.Tselik, N.Tiurina, I.Gorbunov, V.Vladimirov,D.Zimnukhov, V.Senik, A.Yudin,A.Chasovnikov, D.Cheryasov, A.Sosnovskij (Lomonosov  MSU,SAI,PhysicsDepartment),
O.A. Gres, N.M. Budnev (Irkutsk State University, API),
C.Francile.  F. Podesta, R.Podesta (Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra(The Instituto de Astrofisica de Canarias),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity)

MASTER Global robotic net (http://observ.pereplet.ru Lipunov et al.,2010,Advances in Astronomy,2010,30L)
started Swift GRB 231215C ( D'Avanzo et al GCN 35343, Evans et al. GCN35345)
at 2023-12-15 10:33:29UT (Lipunov et al. GCN 35346)

There is MASTER OT J003857.44+573850 since first image with mOT=16.5 at one of first image, with classical GRB light curve
Observations and reduction will be continued


GRB_name: GRB231214A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35348
SUBJECT: GRB 231214A: AstroSat CZTI detection
DATE:    23/12/15 12:16:26 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-duration GRB 231214A which was also detected by Fermi-GBM (Fermi GBM Team, GCN Circ. 35334), Swift-BAT (Brivio et al., GCN Circ. 35335), and Fermi-LAT (Kocevski et al., GCN Circ. 35342).

The source was clearly detected in three of four quadrants of CZT detectors in the 20-200 keV energy range. AstroSat was approaching the South Atlantic Anomaly (SAA) region and hence the background rates were higher. The light curve showed multiple peaks of emission with the strongest peak at 2023-12-14 20:24:41.50 UTC. We limit our analysis to a single quadrant with a relatively stable background. The measured peak count rate associated with the burst is 99 (+28, -12) counts/s above the background in the data of one quadrant (out of four), with a total of 691 (+127, -135) counts. The local mean background count rate was 99 (+2, -2) counts/s. Using cumulative rates, we measure a T90 of 20 (+1, -1) s.

The source was also 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 2023-12-14 20:24:29.95 UTC. The measured peak count rate associated with the burst is 245 (+84, -30) counts/s above the background in the combined data of all quadrants, with a total of 2761 (+591, -655) counts. The local mean background count rate was 1761 (+8, -9) counts/s. We measure a T90 of 22 (+3, -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: GRB231215A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35349
SUBJECT: GRB 231215A: Mondy optical bright afterglow detection
DATE:    23/12/15 12:55:34 GMT
FROM:    Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>

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

We observed the field of Swift GRB 231215A (D'Avanzo et al., GCN 35343; Evans et al., GCN 35345)  with AZT-33IK telescope of Mondy observatory  in  R-filter starting  on  2023-12-15 (UT) 11:17:39.  Preliminary photometry of the fist immaes reveals a new bright source within XRT error circle (Evans et al., GCN 35345)

Date       UT start  t-T0     Exp.   Filter   OT     Err.
                   (mid, days)  (s)
2023-12-15 11:17:39  0.063363  1x120 R        17.42  0.07
 
The photometry is based on nearby USNO-B1.0 R2 stars.
 
We also may suggest that GCN 35347 (Lipunov et al.) refer to the afterglow of GRB 231215A.


GRB_name: GRB231214A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35350
SUBJECT: GRB 231214A: Swift-XRT refined Analysis
DATE:    23/12/15 13:27:53 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

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

We have analysed 6.2 ks of XRT data for GRB 231214A, from 407 s to 45.5
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=1.48 (+/-0.08).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.4 (+/-0.4). The
best-fitting absorption column is  1.2 (+0.4, -0.3) x 10^22 cm^-2, in
excess of the Galactic value of 5.5 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 4.2 x 10^-11 (1.2 x 10^-10) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.2 (+0.4, -0.3) x 10^22 cm^-2
Galactic foreground: 5.5 x 10^20 cm^-2
Excess significance: 5.4 sigma
Photon index:      2.4 (+/-0.4)

If the light curve continues to decay with a power-law decay index of
1.48, the count rate at T+24 hours will be 1.6 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.9 x
10^-14 (1.9 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/01202386.

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


GRB_name: GRB231215A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35351
SUBJECT: GRB 231215A : MITSuME Akeno optical afterglow candidate detection
DATE:    23/12/15 13:31:43 GMT
FROM:    Mahito Sasada at Tokyo Institute of Technology <sasada@hp.phys.titech.ac.jp>

M. Sasada, N. Higuchi, I. Takahashi, M. Niwano, S. Sato, S. Hayatsu, H. Takei, H. Seki, Y. Yatsu and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration:

We observed the field of GRB 231215A (D'Avanzo et al., GCN 35343) 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 10 sec exposures started at 2023-12-15 09:50:27 UT (182 seconds after the Swift/BAT trigger). We stacked the first six images. An optical candidate of the afterglow can be found at the location of (RA, Dec) = (9.7393, 57.6472) near the Swift/XRT error position (Evans et al., GCN 35345). Here we report magnitudes by the aperture photometry at the position.

T0+[sec] | MID-UT | T-EXP[sec] | magnitudes of aperture photometry
----------------------------------------------------------------------------------------------------------------
238 | 2023-12-15 09:51:23 | 60 | gâ€™=17.54+/-0.06, Rc=17.86+/-0.05, Ic=17.40+/-0.05
----------------------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the trigger
T-EXP: Total Exposure time

The magnitudes are consistent with Lipunov et al., GCN 35347 and Pankov et al., GCN 35349. We are continuing to observe the candidate.

We used the PS1 catalog for flux calibration. The catalog magnitudes in PS1 g, r and i bands were converted to our g'-, Rc- and Ic-band magnitudes following Tonry et al. (2012), Table 6. 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: GRB231215A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35352
SUBJECT: GRB 231215A: AstroSat CZTI detection
DATE:    23/12/15 14:11:50 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 bright long-duration GRB 231215A which was also detected by Swift-BAT (D'Avanzo et al., GCN Circ. 35343), and Fermi-GBM (Fermi GBM Team, GCN Circ. 35344).

The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed two peaks of emission with the strongest peak at 2023-12-15 09:47:26.50 UTC. The measured peak count rate associated with the burst is 775 (+59, -30) counts/s above the background in the combined data of three quadrants (out of four), with a total of 8196 (+334, -292) counts. The local mean background count rate was 267 (+3, -3) counts/s. Using cumulative rates, we measure a T90 of 15 (+1, -1) s. In the preliminary analysis, we find 1372 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 two peaks of emission with the strongest peak at 2023-12-15 09:47:25.92 UTC. The measured peak count rate associated with the burst is 2162 (+110, -46) counts/s above the background in the combined data of all quadrants, with a total of 22784 (+686, -737) counts. The local mean background count rate was 1465 (+6, -7) counts/s. We measure a T90 of 14 (+1, -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: GRB231215A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35353
SUBJECT: GRB 231215A : Nanshan/HMT optical observations
DATE:    23/12/15 14:32:20 GMT
FROM:    Dong Xu at NAOC/CAS <dxu@nao.cas.cn>

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

We observed the field of GRB 231215A detected by Swift (D'Avanzo et al., GCN 35343) using the HMT-0.5m telescope located at Nanshan, Xinjiang, China. Observations started at 11:51:08 UT on 2023-12-15, i.e., 2.06 hr after the BAT trigger. A series of 90, 120, 200 s frames without any filter have been obtained and observations are ongoing.

Preliminary analysis of the initial frames shows that the previously reported optical afterglow (e.g., Pankov et al., GCN 35349; Sasada et al., GCN 35351) has decayed to m(r) = 18.3 +/- 0.1 mag at 2.19 hr post-burst, calibrated with the nearby PanSTAR field in the Sloan r-filter and the magnitude is not corrected for Galactic extinction.


GRB_name: GRB231215A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35354
SUBJECT: GRB 231215A: GROWTH-India optical follow-up
DATE:    23/12/15 15:35:12 GMT
FROM:    Vishwajeet Swain at IIT Bombay <vishwajeet.s@iitb.ac.in>

Y. Wagh, R. Kumar, V. Swain, A. Salgundi, V. Bhalerao (IIT Bombay), G. C. Anupama, S. Barway (IIA), K. Angail (IAO)

We observed the field of GRB 231215A detected by Swift (D'Avanzo et al., GCN Circ. 35343) with 0.7m GROWTH-India Telescope (GIT). We started the observation at 2023-12-15 13:48:10.312 UT, i.e., 4.01 hours after the Swift trigger. We obtained multiple images in the r' and g' filters. We clearly detected the afterglow near the uncertainty radius of Swift-XRT position reported by P.A. Evans et al., GCN Circ. 35345 and are consistent with the coordinate reported by M. Sasada at al., GCN Circ. 35351. The photometry results follow as:

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

| JD (mid) | t-t0 (hours) | Filter | Exposure (s) | Magnitude (AB) |

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

| 2460294.07510789 | 4.008 | r' | 380 | 19.65 +/- 0.08 | 
| 2460294.08452486 | 4.248 | g' | 380 | 20.44 +/- 0.11 | 

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

The results are consistent to the values reported by V.Lipunov et al., GCN Circ. 35347; N. Pankov et al., GCN Circ. 35349; M. Sasada et al., GCN Circ. 35351; J. An et al., GCN Circ. 35353. The magnitudes are calibrated against PanSTARRS DR1 (Chambers et al., 2016) and are 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: GRB231214A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35355
SUBJECT: GRB 231214A: REM optical/NIR upper limits
DATE:    23/12/15 16:02:09 GMT
FROM:    Matteo Ferro <matteo.ferro@inaf.it>

M. Ferro, R. Brivio, P. D'Avanzo, S. Covino, D. Fugazza (INAF-OAB) on behalf of the REM team, report:

We observed the field of GRB 231214A (Brivio et al., GCN 35335) with the REM 60cm robotic telescope located at the ESO Observatory of La Silla (Chile). The observations were carried out in the g,r,i,z, J,H,K bands, starting on 2023 Dec 15 at 00:39:27 UT (i.e. about 4.25 hours after the Swift trigger) and lasted for about 1 hour.
From preliminary analysis, we do not find any source at the enhanced XRT position (Evans et al., GCN 35341), down the the following 3 sigma upper limits:

r > 20.1 (AB; calibrated against the SkyMapper catalogue)
at a mid time of t-t0 ~ 4.92 h after the GRB trigger;

H > 17.7 (Vega; calibrated against the 2MASS catalogue)
at a mid time of t-t0 ~ 4.68 h after the GRB trigger.


GRB_name: GRB231215A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35357
SUBJECT: GRB 231215A: Enhanced Swift-XRT position
DATE:    23/12/15 16:29:06 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 1725 s of XRT Photon Counting mode data and 4 UVOT
images for GRB 231215A, 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 = 9.73958, +57.64793 which is equivalent
to:

RA (J2000): 00h 38m 57.50s
Dec (J2000): +57d 38' 52.6"

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: GRB231210B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35358
SUBJECT: ATCA observations of GRB 231210B
DATE:    23/12/15 16:40:25 GMT
FROM:    Lauren Rhodes at Oxford <lauren.rhodes@physics.ox.ac.uk>

L. Rhodes (Oxford), G. E. Anderson (Curtin), A. J. van der Horst (GWU), J. K. Leung (UofT/HUJI), O. Sharan Salafia (INAF), S. D. Ryder (Macquarie),  A. Gulati (USyd), S. Chastain (UNM) on behalf of the PanRadio GRB collaboration

We observed short GRB 231210B (Page et al., GCN 35314) starting at 2023-12-14 10:56UT for 9 hours with the Australia Telescope Compact Array (ATCA), as part of the "PanRadio GRB" Large ATCA follow-up programme C3542 (PI. Anderson).

We do not detect any clear radio counterpart. The rms noise in our observations is 17 and 12 uJy/beam at 5.5 and 9GHz, respectively. At a redshift of 3.13 (Saccardi et al GCN 35317), our measurements correspond to 3-sigma upper limits of 6.6e30 and 4.7e30 erg/s/Hz at 5.5 and 9GHz, respectively (assuming H0 = 70km/s/Mpc and OmegaM = 0.3)

We thank the CSIRO Space and Astronomy staff for supporting these observations.
We acknowledge the Gomeroi people as the traditional owners of the Observatory site. The Australia Telescope Compact Array is part of the Australia Telescope National Facility (https://ror.org/05qajvd42) which is funded by the Australian Government for operation as a National Facility managed by CSIRO.


GRB_name: GRB231210B
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35359
SUBJECT: Konus-Wind detection of GRB 231210B
DATE:    23/12/15 16:58:32 GMT
FROM:    Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>

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

The long GRB 231210B (Swift detection: Page et al., GCN 35314)
triggered Konus-Wind (KW) at T0=77347.988 s UT (21:29:07.988).

The burst light curve shows a multi-peaked structure
with a total duration of of ~9 s.
The emission is seen up to ~0.5 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB231210_T77347/

As observed by Konus-Wind, the burst had
a total fluence of (4.02 Â± 0.56)x10^-6 erg/cm^2 and
a 64-ms peak energy flux, measured from T0+2.944 s,
of (2.19 Â± 0.32)x10^-6 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum of the burst (measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 15 MeV range by a power law with exponential
cutoff (CPL) model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.62(-0.37,+0.44) and Ep = 174(-27,+40) keV (chi2 = 65/87 dof).
Fitting this spectrum by a Band function yields the same values of alpha and Ep,
and an upper limit on the high energy photon index beta of -2.5 (chi2 = 65/86 dof).

Assuming the redshift z=3.13 (Saccardi et al., GCN 35317)
and a standard cosmology with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315,
and Omega_Lambda = 0.685 (Planck Collaboration, 2014),
we estimate the burst isotropic energy release E_iso to (8.8 Â± 1.3)x10^52 erg,
the isotropic peak luminosity L_iso to (2.0 Â± 0.3)x10^53 erg/s,
the rest-frame peak energy of the spectrum Ep,z to ~720 keV.
With the obtained estimates, GRB 231210B is inside 90% prediction band for
the 'Amati' relation and inside 68% prediction band for the 'Yonetoku' relation
derived for the sample of >300 long KW GRBs with known redshifts
(Tsvetkova et al., 2017; Tsvetkova et al., 2021), see
http://www.ioffe.ru/LEA/GRBs/GRB231210_T77347/GRB231210B_rest_frame.pdf

All the quoted errors are estimated at the 68% confidence level.
All the presented results are preliminary.


GRB_name: GRB231214A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35360
SUBJECT: GRB 231214A: Fermi GBM observation
DATE:    23/12/15 18:56:47 GMT
FROM:    sumanbala2210@gmail.com

S. Bala (USRA) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 20:24:24.68 UT on 14 December 2023, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 231214A (trigger 724278269 / 231214850),
which was also detected by the Swift/BAT (Brivio et al. 2023, GCN 35335),
Fermi-LAT (Kocevski et al. 2023, GCN 35342) and AstroSat CZTI (Navaneeth et al. 
GCN 35348). The Fermi GBM Final Real-time Localization (GCN 35334) is consistent
with the Swift position. 

The angle from the Fermi LAT boresight at the GBM trigger time is 50.0 degrees.

The GBM light curve consists of two distinct peaks
with a duration (T90) of about 21 s (50-300 keV).
The time-averaged spectrum from T0-0.5 s to T0+26.1 s is
best fit by a Band function with Epeak = 142.5 +/- 5 keV,
alpha = -0.46 +/- 0.05, and beta = -2.5 +/- 0.1.

The event fluence (10-1000 keV) in this time interval is
(2.25 +/- 0.05)E-5 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+16.12 s in the 10-1000 keV band
is 22.24 +/- 1.77 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: GRB231215A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35361
SUBJECT: GRB 231215A: AGILE detection
DATE:    23/12/15 20:12:46 GMT
FROM:    Francesco Verrecchia at SSDC,INAF-OAR <francesco.verrecchia@ssdc.asi.it>

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

The AGILE satellite detected the GRB 231215A at T0 = 2023-12-15
09:47:17.8 s (UTC), reported by Swift (GCNs #35343, #35345, #35357),
Mondy (GCN #35349), MITSuME (GCN #35351), Astrosat (GCN #35352),
HMT (GCN #35353), GROWTH (GCN #35354).

The event lasted about 12 s and it released a total number of 10990
counts in the MCAL detector RM (above a background rate of 548 Hz)
and 49280 counts in the AC-Top detector RM (above a background
rate of 2741 Hz). The AGILE ratemeters light curves can be
found at

http://www.agilescienceapp.it/notices/GRB231215A_AGILE_RM_ND.png .

The event also triggered a high time resolution MCAL data acquisition,
from T0-22 s s to T0+10 s (UTC), and released 8436 counts in the
detector, above a background rate of 510 Hz.
The MCAL light curve can be found at

http://www.agilescienceapp.it/notices/GRB231215A_086695_629718437.810000.png .

At the T0, the event was 148 deg off-axis.
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: GRB231215A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35362
SUBJECT: GRB 231215A: AKO Optical Upper Limit
DATE:    23/12/15 21:33:00 GMT
FROM:    Mohammad Odeh at Al Khatim Observatory M44 <mshodeh@gmail.com>

Mohammad Odeh (Al-Khatim Observatory, AKO, operated by the International
Astronomical Center in Abu Dhabi, UAE), and Dalya Akl (American University
of Sharjah, UAE), report:

We used our 0.36m f/7.7 robotic telescope to observe the field of GRB
231215A, which was detected by Swift (D'Avanzo et al., GCN 35343), and its
optical counterpart was detected by (Pankov et al., GCN 35349; Sasada et
al., GCN 35351; An et al., GCN 35353; Wagh et al., GCN 35354).

The observation was done on 15 December starting at 20:07:36 UT, which
corresponds to 10.34 hours after the GRB trigger time, using an (Ic)
filter. We obtained 17x180s images, and we didn't detect a credible source
within the uncertainty radius of the Swift-XRT position (Goad et al., GCN.
35357).

The following 5-sigma upper limit is calculated using the ATLAS catalog as
a reference:
Ic = 18.8
The magnitude is not corrected for Galactic extinction.


GRB_name: GRB231215A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35363
SUBJECT: GRB 231215A: BOOTES-4/MET optical detection
DATE:    23/12/15 21:36:53 GMT
FROM:    Youdong HU at IAA-CSIC <huyoudong072@hotmail.com>

Y.-D. Hu, E. Fernandez-Garcia, I. Perez-Garcia, M.D. Caballero-Garcia, R. Sanchez-Ramirez, S. Guziy, S.-Y. Wu and A. J. Castro-Tirado (IAA-CSIC, Granada), C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga) and D. R. Xiong, Y. F. Fan, J. M. Bai, C. J. Wang, Y. X. Xin, X. H. Zhao (Yunnan Observatories of CAS) on behalf of a larger collaboration, report:

Following the detection of GRB 231215A by Swift (D'Avanzo et al. GCNC 35343) and AGILE (Verrecchia et al. GCNC 35361), the 0.6m BOOTES-4/MET robotic telescope at Lijiang Astronomical Observatory (China) automatically responded to this burst starting on Dec. 15 at 14:11 UT (~4.4 hrs after trigger). A series of images in clear filter were gathered and the optical afterglow was detected within the enhanced Swift/XRT position (Goad et al. GCNC 35357) for which we measure a magnitude of 19.91 +- 0.14 on the co-added 60 s x 15 image, which is consistent with the detections of MASTER (Lipunov et al. GCNC 35347), Mondy (Pankov et al. GCNC 34349), MITSuME (Sasada et al. GCNC 35351), Nanshan/HMT (An et al. GCNC 35353) and GROWTH-India (Wagh et al. GCNC 35354). Further imaging is ongoing.

We thank the staff at Lijiang observatory for their excellent support.


GRB_name: GRB231215A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35364
SUBJECT: GRB 231215A: Swift-XRT refined Analysis
DATE:    23/12/15 22:14:28 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

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

We have analysed 6.7 ks of XRT data for GRB 231215A, from 2.7 ks to
33.0 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=1.95 (+0.10, -0.09).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.89 (+0.20, -0.13). The
best-fitting absorption column is  4.40 (+1.19, -0.15) x 10^21 cm^-2,
consistent with the Galactic value of 4.2 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 4.2 x 10^-11 (6.3 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      4.40 (+1.19, -0.15) x 10^21 cm^-2
Galactic foreground: 4.2 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.89 (+0.20, -0.13)

If the light curve continues to decay with a power-law decay index of
1.95, the count rate at T+24 hours will be 1.9 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.1 x
10^-14 (1.2 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/01202522.

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


GRB_name: GRB231215A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35366
SUBJECT: GRB 231215A: Swift/UVOT Detection
DATE:    23/12/15 22:38:34 GMT
FROM:    Paul Kuin at MSSL <npkuin@gmail.com>

N. P. M. Kuin (UCL-MSSL) and P. D'Avanzo (INAF-OAB)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 231215A
2733 s after the BAT trigger (D'Avanzo et al., GCN Circ. 35343).
A source consistent with the XRT position (Goad et al., GCN Circ. 35357)
is detected in the initial UVOT exposures. The burst was also detected
by Fermi GBM (GCN Circ. 35344),Astrosat CZTI (Navaneeth et al., GCN
Circ. 35352), and in the optical by Master (Lipunov et al., 35347),
MONDY (Pankov et al. GCN Circ. 35349), MITSume Akeno (Sasada et al.,
GCN Circ. 35351), GROWTH-India (Wagh et al., GCN Circ 35354), BOOTES-4/MET
(Hu et al., GCN Circ 35363), HMT-Nanshang (An et al. GCN Circ. 35353) and
an upper limit from AKO (Odeh, GCN Circ. 36362).

The preliminary UVOT position is:
    RA  (J2000) =  00:38:57.52 =   9.73967 (deg.)
    Dec (J2000) = +57:38:50.5  =  57.64735 (deg.)
with an estimated uncertainty of 0.45 arc sec. (radius, 90% confidence).

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             2733         2883          147         18.10 +/- 0.05
v                 3713         3912          197         17.48 +/- 0.08
b                 3096         3296          197         18.63 +/- 0.09
u                 2891         3091          197         18.17 +/- 0.10
w1                4124         4323          197         19.57 +/- 0.31
m2                3918         4117          197        >19.4
w2                3507         3707          197        >19.5

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.506 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB231215A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35367
SUBJECT: GRB 231215A : OHP/T193 optical afterglow detection
DATE:    23/12/15 22:40:38 GMT
FROM:    Damien Turpin at CEA-Saclay <dturpin-astro@hotmail.com>

D. Turpin (CEA Paris-Saclay), C. Adami (LAM), E. Le Floc'h, D. GÃ¶tz, F. SchÃ¼ssler (CEA Paris-Saclay), B. Schneider (MIT), S. Basa (Pytheas/OHP/LAM), A. Saccardi, S. D. Vergani (GEPI, Obs. de Paris), report on behalf of a larger collaboration:

We observed the field of the long GRB 231215A (D'Avanzo et al., GCN 35343) and its afterglow candidate (Evans et al. GCN 35345) using the T193cm telescope at Observatoire de Haute-Provence (France) equipped with the MISTRAL instrument. A total of 5 images were taken in r-band (total exposure = 3000s) and 3 others in the g-band (total exposure = 2100s) starting at 17:13:33.32 UT on 2023-12-15, ~7.43h after the trigger.

In the combined frames, we clearly detect the optical afterglow reported by Lipunov et al. GCN 35347, Pankov et al. GCN 35349, Sasada et al. GCN 35351, An et al. GCN 35353, Wagh et al. GCN 35354, Hu et al. GCN 35363. The preliminary magnitude derived are the following:

-----------------------------------------------
T-T0 (in days, midtime) | mag | filter
-----------------------------------------------
0.3302 | 21.32 Â± 0.10 mag (AB) | r'
0.3795 | 21.76 Â± 0.07 mag (AB) | g'
-----------------------------------------------

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

Our results are compatibe with the fading behavior observed in previous GCN (Lipunov et al. GCN 35347, Pankov et al. GCN 35349, Sasada et al. GCN 35351, An et al. GCN 35353, Wagh et al. GCN 35354, Ferro et al. GCN 35355, Hu et al. GCN 35363). We note that the afterglow flux decay is steep with a temporal index alpha ~ 1.9. We encourage further follow-up observation with large telescopes to better characterize the flux and spectral evolution of this afterglow.

We acknowledge the excellent support from Observatoire de Haute-Provence, in particular Jean Balcaen for the MISTRAL observations and the SOPHIE observer ClÃ©ment Ranc.


GRB_name: GRB231215A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35368
SUBJECT: GRB 231215A: CALET Gamma-Ray Burst Monitor detection
DATE:    23/12/16 03:33:37 GMT
FROM:    Yuta Kawakubo at Louisiana State University <kawakubo1@lsu.edu>

N. Cannady (GSFC/UMBC), A. Yoshida, T. Sakamoto, 
S. Sugita (AGU), Y. Kawakubo (LSU), K. Yamaoka (Nagoya U),
S. Nakahira (JAXA), Y. Asaoka (ICRR), S. Torii, Y. Akaike, 
K. Kobayashi (Waseda U), T. Tamura, Y. Shimizu (Kanagawa U),
M. L. Cherry (LSU), S. Ricciarini (U of Florence),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

The long GRB 231215A (Swift detection of a burst: D'Avanzo et al., 
GCN Circ. 35343; AstroSat CZTI detection: Navaneeth et al., 
GCN Circ. 35352; AGILE detection: Verrecchia et al., GCN Circ. 
35361) triggered the CALET Gamma-ray Burst Monitor 
(CGBM) at 09:47:15.26 UTC on 15 December 2023
(http://cgbm.calet.jp/cgbm_trigger/flight/1386668712/).
The burst signal was seen by all CGBM detectors.

The burst light curve shows a multi-peaked structure that starts
at T+1.5 sec, peaks at T+10.4 sec, and ends at T+20.4 sec.
The T90 and T50 durations measured by the SGM data are 
15.2 +/- 1.3 sec and 5.6 +/- 0.2 sec (40-1000 keV), respectively.

The ground-processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1386668712/index.html

The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.


GRB_name: GRB231215A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35369
SUBJECT: GRB 231215A: Fermi GBM observation
DATE:    23/12/16 07:57:56 GMT
FROM:    Elisabetta Bissaldi at Politecnico and INFN Bari <elisabetta.bissaldi@ba.infn.it>

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


"At 09:47:17.81 UT on 15 December 2023, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 231215A (trigger 724326442 / 231215408),
which was also detected by the Swift/BAT (D'Avanzo et al. 2023, GCN 35343).
The GBM on-ground location is consistent with the Swift position.
We note that the burst was automatically named incorrectly (GRB 231215B, GCN 35344),
likely because the GBM trigger differs from the BAT trigger by 8 s.

The angle from the Fermi LAT boresight
at the GBM trigger time is 111 degrees.

The GBM light curve consists of a single bright pulse
with a duration (T90) of about 16 s (50-300 keV).
The time-averaged spectrum from T0-1.8 s to T0+32 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is 0.73 +/- 0.02 and
the cutoff energy, parameterized as Epeak, is 761 +/- 22 keV.

The event fluence (10-1000 keV) in this time interval is
(7.15 +/- 0.05)E-5 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+7.5 s in the 10-1000 keV band
is 20.3 +/- 0.4 ph/s/cm^2.

A Band function fits the spectrum equally well
with Epeak= 759 +/- 23 keV, alpha = -0.73 +/- 0.02
and beta = 4.7 +/- 1.4.


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: GRB231215A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35370
SUBJECT: GRB 231215A: GAD Observatory, La Spezia, Italy upper limit;
DATE:    23/12/16 11:12:34 GMT
FROM:    Claudio Lopresti <cl3lop@gmail.com>

Claudio Lopresti (Gruppo Astronomia Digitale - GAD Observatory, La Spezia, Italy) in 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), Unione Astrofili Italiani (UAI)
report:

We imaged the field of GRB 231215A (trigger=1202522) with the telescope LX200 12â€ of GAD Observatory, La Spezia, Italy
Member of:
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili, GRB section.
GAD - Gruppo Astronomia Digitale.

The observations started 551 min after the GRB trigger, with a Shmidt-Cassegrain telescope D=304 mm with reducer F/D=4.75.

Weather conditions were medium.
The observation with a series of 60 sec exposures started at 2023-12-15 18:58:47 UT 

We co-added 230 exposures of 60 sec each.

Start T0+      End T0+       R lim
551 min        815 min      17,99

We did not found any optical counterpart in 00:38:58.02 +57:38:47.2 position and in the error box of the XRT  candidate.
ref.: P. D'Avanzo et al. GCN 35343, P.A. Evans et al. GCN 35345

Magnitudes were estimated with the Gaia EDR3 cat. and
are not corrected for galactic dust extinction.

Reference:
https://www.parcodellestelle.com/

The message may be cited. 


GRB_name: GRB231204A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35371
SUBJECT: GRB 231204A: VZLUSAT-2 detection
DATE:    23/12/16 11:17:21 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 231204A (Fermi/GBM detection: GCN 35258; AstroSat detection: GCN 35267; CALET/CGBM detection: GCN 35272; Glowbug detection: GCN 35274; Konus/WIND detection at 2023-12-04 20:00:04.344 UT; INTEGRAL/SPI-ACS peak detection at 2023-12-04 ~20:00:05 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 2023-12-04 20:00:07 UTC. The T90 duration is 5 s and the significance during T90 reaches 6 sigma (10 sigma) for detector unit no. 0 (no. 1).

The light curve obtained by VZLUSAT-2 is available here:
https://vzlusat2.konkoly.hu/static/share/GRB231204A_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: GRB231205B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35372
SUBJECT: GRB 231205B: VZLUSAT-2 detection
DATE:    23/12/16 11:18:20 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 231205B (Swift/BAT detection: GCN 35269; GECAM-B detection: GCN 35279; AGILE detection: GCN 35295; Konus/WIND detection at 2023-12-05 16:43:58.336 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 2023-12-05 16:43:57 UTC. The T90 duration is 31 s (29 s) and the significance during T90 reaches 14 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/GRB231205B_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: GRB231215A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35373
SUBJECT: GRB 231215A: Redshift from OSIRIS+ / GTC
DATE:    23/12/16 12:43:06 GMT
FROM:    Christina ThÃ¶ne at ASU-CAS <christina.thoene@gmail.com>

C. C. Thoene (ASU-CAS), A. de Ugarte Postigo (CNRS/OCA and LAM), J. F. Agui Fernandez (CAHA), L. Izzo (INAF/Capodimonte), J. P. U. Fynbo (DAWN/NBI), N. R. Tanvir (U. Leicester), M. Blazek (CAHA), S. Geier, A. Cabrera-Lavers, Fabricio Perez Toledo and Miguel Rivero (all GTC) report:
 
We obtained spectroscopy of the afterglow of GRB 231215A (Dâ€™Avanzo et al. GCN 35343, Evans et al. GCN 35345, Pankov et al. GCN 35349) with OSIRIS+ at the 10.4m GTC at a mean epoch of 0.4958 days after the GRB. The observation consisted of 3x900s exposures with grism R1000B, covering the range between 3700 and 7780 AA at a resolving power of about 600.

The spectrum shows a strong but reddened continuum with multiple absorption features. The highest redshift features include Lyman alpha, SII 1250,53,59, SiII1260, 1304, OI1302, CII 1334, SiIV1393, 1402, CIV 1548, 1550, AlII1670, FeII 1608, 1611 at a common redshift of z=2.305. We also identify fine structure lines of SiII* 1264 and 1309 at the same redshift, which we hence assume as the redshift of the GRB. Additionally, we detect two intervening systems, at z=2.076 showing CIV and SiIV absorption and at z=0.574 showing the MgII 2796, 2803 doublet.

We thank the GTC staff for excellent support. This GRB reached Earth on the name's day of the first author. 


GRB_name: GRB231214A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35374
SUBJECT: GRB 231214A: Swift/UVOT Upper Limits
DATE:    23/12/16 13:23:14 GMT
FROM:    Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL) and Brivio (INAF-OAB) report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 231214A (Fermi GBM Team, GCN Circ. 35334; Kocevski et al., GCN Circ. 35342; Navaneeth et al., GCN Circ. 35348), 442 s after the BAT trigger (Brivio et al., GCN Circ. 35335).
No optical afterglow consistent with the XRT position (Evans et al., GCN Circ. 35341) 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 initial exposures are:

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

white              442         4733          382         >20.7
v                  4944          4998           54         >18.1
b                  4329         4528          197         >19.6
u                  4123         4322          197         >19.3
w2                4739         4939          197         >19.5

The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.060 in the direction of the burst (Schlegel et al. 1998).


GRB_name: GRB231215A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35375
SUBJECT: GRB 231215A: NOT optical observations
DATE:    23/12/16 16:50:36 GMT
FROM:    Zipei Zhu at NAOC <zpzhu@nao.cas.cn>

Z. Zhu, J. An, D. Xu (NAOC), D. B. Malesani (DAWN/NBI), L. Izzo (INAF/Capodimonte), A. de Ugarte Postigo (CNRS/OCA and LAM), Z. Gray (NOT) report on behalf a large collaboration:

We observed the optical afterglow of GRB 231215A detected by Swift/BAT (Dâ€™Avanzo et al., GCN 35343, Evans et al., GCN 35345, Pankov et al., GCN 35349), using the 2.56-m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Observations started at 20:23:33 UT on 2023-12-15, i.e., 10.6 hr after the BAT trigger. We obtained 2x120 s in the Sloan r-band and then 2x1800 s spectroscopy.

The previously reported optical counterpart (e.g., Lipunov et al., GCN 35347, Pankov et al., GCN 35349, Sasada et al., GCN 35351, An et al., GCN 35353, Wagh et al., GCN 35354, Hu et al., GCN 35363, Turpin et al., GCN 35367) was clearly detected in our stacked image with m(r) = 21.21 +/- 0.03 at 10.64 hr post-burst, calibrated with nearby Pan-STARRS stars.

However, the S/N of the spectrum is quite low. The spectrum shows a rather flat and featureless continuum. No unambiguous absorption feature can be identified at the reported GTC redshift (Thoene et al., GCN 35373).


GRB_name: GRB231215A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35376
SUBJECT: GRB 231215A: optical afterglow detection from the INAF Asiago Observatory
DATE:    23/12/16 18:18:47 GMT
FROM:    Paolo D'Avanzo at INAF-OAB <pda.davanzo@gmail.com>

A. Reguitti (INAF-OAB / INAF-OAPd), P. D'Avanzo (INAF-OAB), L. Tomasella (INAF -OAPd), E. Cappellaro (INAF -OAPd), 
report on behalf of the CIBO and of the GRAWITA collaborations: 

We carried out follow-up optical observations of GRB 231215A (D'Avanzo et al., GCN Circ. 35343; Navaneeth et al. GCN Circ. 35352; 
Verrecchia et al. GCN Circ. 35361; Cannady et al., GCN Circ. 35368; Bissaldi et al., GCN Circ. 35369) from the INAF - Padova Astronomical 
Observatory located in Asiago (Italy) with the 67/92 Schmidt telescope starting on 2023-12-15 at 16:45:00 UT (~ 7.0 hours after the burst) 
with the clear filter.

In our stacked image the optical afterglow (Lipunov et al., GCN Circ. 35347, Pankov et al., GCN Circ. 35349, Sasada et al., GCN Circ. 35351, 
An et al., GCN Circ. 35353, Wagh et al., GCN Circ. 35354, Hu et al., GCN Circ. 35363; Kuin et al., GCN Circ. 35366; Turpin et al., GCN Circ. 
35367; Zhu et al., GCN Circ. 35375) is detected. 
From preliminary analysis we estimate a magnitude of 21.2 +/- 0.2 (AB; calibrated against r band of the PanSTARRS catalog).


GRB_name: GRB231215A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35377
SUBJECT: Konus-Wind detection of GRB 231215A
DATE:    23/12/16 18:27:11 GMT
FROM:    Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>

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

The long, bright GRB 231215A (Swift detection: D'Avanzo et al., GCN 35343;
AstroSat CZTI detection: Navaneeth et al., GCN 35352;
CALET Gamma-Ray Burst Monitor detection: Cannady et al., GCN 35368;
AGILE detection: Verrecchia et al., GCN 35361;
Fermi GBM detection: Lesage et al., GCN 35369)
triggered Konus-Wind (KW) at T0=35239.795 s UT (09:47:19.795).

The burst light curve shows a single multi-peaked pulse,
which starts at ~T0-1 s, peaks at ~T0+9.5 s,
and has a total duration of ~25 s.
The emission is seen up to ~10 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB231215_T35239/

As observed by Konus-Wind, the burst had
a fluence of (1.02 Â± 0.09)x10^-4 erg/cm^2 and
a 64-ms peak energy flux, measured from T0 + 28.352 s,
of (1.14 Â± 0.12)x10^-5 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+24.320 s)
is best fit in the 20 keV - 15 MeV range
by a GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.67 (-0.07,+0.08),
the high energy photon index beta = -2.49 (-0.43,+0.22),
the peak energy Ep = 612 (-63,+74) keV,
chi2 = 80/97 dof.

The spectrum near the peak count rate (measured from T0+6.400s to T0+9.984s)
is best fit in the 20 keV - 15 MeV range
by a GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.49 (-0.09,+0.09),
the high energy photon index beta = -3.07 (-2.04,+0.44),
the peak energy Ep = 582 (-54,+58) keV,
chi2 = 69/80 dof.

Assuming the redshift z=2.305 (Thoene et al., GCN 35373)
and a standard cosmology with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315,
and Omega_Lambda = 0.685 (Planck Collaboration, 2014),
we estimate the burst isotropic energy release E_iso to (1.35 Â± 0.12)x10^54 erg,
the isotropic peak luminosity L_iso to (4.93 Â± 0.49)x10^53 erg/s,
the rest-frame peak energy of the time-integrated spectrum Ep,i,z to ~2023 keV,
and the rest-frame peak energy at the peak of the emission Ep,p,z to ~1924 keV.
With the obtained estimates, GRB 230818A is inside 68% prediction band for
both 'Amati' and 'Yonetoku' relations derived for the sample of >300 long
KW GRBs with known redshifts (Tsvetkova et al., 2017; Tsvetkova et al., 2021),
see http://www.ioffe.ru/LEA/GRBs/GRB231215_T35239/GRB231215A_rest_frame.pdf

All the quoted errors are estimated at the 68% confidence level.
All the presented results are preliminary.


GRB_name: GRB231216A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35378
SUBJECT: GRB 231216A: Swift detection of a burst
DATE:    23/12/16 18:56:07 GMT
FROM:    Tullia Sbarrato at INAF-OAB <tullia.sbarrato@inaf.it>


T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), S. Dichiara (PSU),
M. Ferro (INAF-OAB), J.D. Gropp (PSU), S. Laha (GSFC/UMBC),
M. J. Moss (GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL),
B. Sbarufatti (INAF-OAB) and M. H. Siegel (PSU) report on behalf of
the Neil Gehrels Swift Observatory Team:

At 18:35:42 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 231216A (trigger=1202749).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 39.759, +33.596 which is 
   RA(J2000) = 02h 39m 02s
   Dec(J2000) = +33d 35' 45"
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 70 sec.  The peak count rate
was ~2000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 18:37:53.1 UT, 131.1 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source located at RA, Dec 39.77287, 33.57671 which
is equivalent to:
   RA(J2000)  = 02h 39m 05.49s
   Dec(J2000) = +33d 34' 36.2"
with an uncertainty of 3.9 arcseconds (radius, 90% containment). This
location is 80 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 consistent with the Galactic value of 8.36
x 10^20 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 250 seconds with the U filter starting
191 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 33% of the
XRT error circle. The typical 3-sigma upper limit has been about 19.2 mag. 
Results from the list of sources generated on-board are not available at this
time. No correction has been made for the expected extinction corresponding to
E(B-V) of 0.081. 

Burst Advocate for this burst is T. Sbarrato (tullia.sbarrato 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: GRB231215A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35380
SUBJECT: GRB 231215A: GRBAlpha detection
DATE:    23/12/16 19:56:14 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, L. Szakszonova, 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 231215A (Swift/BAT detection: GCN 35343; Fermi/GBM detection: GCN 35344; AstroSat detection: GCN 35352; AGILE detection: GCN 35361; CALET/CGBM detection: GCN 35368; Konus/Wind detection: GCN 35377; INTEGRAL/SPI-ACS peak detection at 2023-12-15 ~09:47:26 UT) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; arXiv:2302.10048).

The detection was confirmed at the peak time 2023-12-15 09:47:27 UTC. The T90 duration measured by GRBAlpha is 16 s and the overall significance during T90 reaches 42 sigma.

The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB231215A_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: GRB231216A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35381
SUBJECT: GRB 231216A: BOOTES-2/TELMA optical upper limit
DATE:    23/12/16 20:47:29 GMT
FROM:    Youdong HU at IAA-CSIC <huyoudong072@hotmail.com>

Y.-D. Hu, E. Fernandez-Garcia, A. J. Castro-Tirado, M.D. Caballero-Garcia, R. Sanchez-Ramirez, I. Perez-Garcia, S.-Y. Wu, S. Guziy  (IAA-CSIC), C. Perez del Pulgar, A. Castellon, I. Carrasco, A. Reina (Univ. de Malaga), R. Fernandez-Munoz (IHSM/UMA-CSIC) and M. Jelinek (ASU-CAS), on behalf of a larger collaboration, report:

Following the detection of GRB 231216A by Swift (Sbarrato et al., GCNC 35378), the 0.6m BOOTES-2/TELMA robotic telescope at IHSM La Mayora (UMA-CSIC) in Algarrobo Costa (Malaga, Spain) automatically pointed to the burst position on Dec. 16 at 18:41:57 UT (i.e. ~51 s after notice, 5.3 min after trigger). In the co-added image (28 x 10 s, clear filter), no optical afterglow is detected within the XRT position down to 20.0 mag, which is consistent with both reports from UVOT (Sbarrato et al., GCNC 35378) and MASTER (Lipunov et al. GCNC 35379).

We thank the staff at IHSM/UMA-CSIC La Mayora for their excellent support.


GRB_name: GRB231216A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35382
SUBJECT: GRB 231216A: NOT optical upper limits
DATE:    23/12/16 22:12:21 GMT
FROM:    Daniele B. Malesani at IMAPP / Radboud University <d.malesani@astro.ru.nl>

Daniele B. Malesani (DAWN/NBI and Radboud Univ.), Jacco H. Terwel (TCD and NOT), Benjamin N. Hauptmann (DTU Space and NOT) report on behalf of a larger collaboration:

We observed the position of GRB 231216A (Sbarrato et al., GCN 35378) using the Nordic Optical Telescope equipped with the ALFOSC images. Observations were carried out in the SDSS r and z filters, with an exposure time of 4x200 s in each filter. The delivered seeing in the combined images was around 1.5", and some calima affected the sky transparency.

Within (or near) the current XRT error circle, we detect no new objects down to magnitudes r > 23.5 and z > 21.5 (both AB), with mean times 2.25 and 2.44 hr after the trigger, respectively. 


GRB_name: GRB231216A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35383
SUBJECT: GRB 231216A: GIT optical upper limit
DATE:    23/12/16 22:30:41 GMT
FROM:    Vishwajeet Swain at IIT Bombay <vishwajeet.s@iitb.ac.in>

R. Sharma, V. Swain, V. Bhalerao (IIT Bombay), S. Barway, G. C. Anupama (IIA), K. Angail (IAO)

We observed the field of GRB 231216A detected by Swift (Sbarrato et al., GCN Circ. 35378) with 0.7m GROWTH-India Telescope (GIT). The observations started at 18:59:01.9 UT on 2023-12-16, i.e., 23 minutes after the BAT trigger. We obtained the multiple exposures of 100 and 300 sec in the g' and r' filters. In our stacked images, we did not detect the afterglow within the Swift-XRT position. The obtained upper limits follow as:

JD (mid) | t_mid-t0 (hours)| Filter | Exposure (s) | Limiting Magnitude (5 sigma) |

2460295.3278711 | 1.27 | r' | 5100 (stacked) | 22.0 |
2460295.3648310 | 2.16 | g' | 1500 (stacked) | 21.0 |

Our results are consistent with the upper limits reported by Global MASTER-Net (Lipunov et al., GCN Circ. 35379), BOOTES-2/TELMA (Hu et al., GCN Circ. 35381) and NOT (Malesani et al., GCN Circ. 35382). 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: GRB231216A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35384
SUBJECT: GRB 231216A: R-band observations from T120 at Observatoire de Haute-Provence
DATE:    23/12/16 23:40:34 GMT
FROM:    Christophe Adami at LAM <christophe.adami@lam.fr>

S. Basa (OHP/PythÃ©as/LAM), C. Adami (PythÃ©as/LAM), Y. Degot-Longhi (OHP/PythÃ©as), A. Saccardi (GEPI, Obs. de Paris), D. Adrien, E. Le Floc'h, F. SchÃ¼ssler,
D. Turpin (CEA Paris-Saclay), report on behalf of a larger collaboration:

We observed the field of GRB231216A (GCN 35378; Sbarrato et al.) using the T120cm camera at Observatoire de Haute-Provence (France).
We began our observations on 2023 16 December 21:37:24 UT (~3h after the trigger time) with a series of R-band (10x300s) images. 
Last image was taken at 22:37:51 UT. 

Consistently with Lipunov et al. (GCN 35379), Hu et al. (GCN 35381), Malesani et al. (GCN 35382), and Sharma et al. (GCN 35383), we did not 
detect any credible optical counterpart to GRB231216A within the GCN 35378 Swift XRT error box.

Using the r-band PanStarr public image, the faintest detected object in our R-band image with a measured PanStarr magnitude is at rMeanPSFMag=22.2.


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


GRB_name: GRB231214A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35385
SUBJECT: GRB 231214A: Swift-BAT refined analysis
DATE:    23/12/17 04:55:15 GMT
FROM:    Takanori Sakamoto at AGU <tsakamoto@phys.aoyama.ac.jp>

M. Stamatikos (OSU), S. D. Barthelmy (GSFC), R. Brivio (INAF-OAB),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa),
C. B. Markwardt (GSFC), M. Moss (GSFC), D. M. Palmer (LANL),
T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU)
(i.e. the Swift-BAT team):
 Using the data set from T-35 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 231214A (trigger #1202386)
(Brivio, et al., GCN Circ. 35335).  The BAT ground-calculated position is
RA, Dec = 305.666, -72.432 deg which is
   RA(J2000)  =  20h 22m 39.7s
   Dec(J2000) = -72d 25' 54.3"
with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 39%.
 The mask-weighted light curve shows two bright overlapping peaks.  The first
peak starts from T-5 s, peaks at T+1 s and ends at T+10 s.  The second peak
starts from T+10 s, peaks at T+12 s and ends at T+25 s.
T90 (15-350 keV) is 27.8 +- 7.3 sec (estimated error including systematics).
 The time-averaged spectrum from T-5.37 to T+49.42 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 0.87 +- 0.23,
and Epeak of 167 +- 94 keV (chi squared 60.53 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 9.6 +- 0.3 x 10^-6 erg/cm2
and the 1-sec peak flux measured from T+12.57 sec in the 15-150 keV band is
11.3 +- 0.6 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.25 +- 0.05 (chi squared 69.34 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/1202386/BA/


GRB_name: GRB231215A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35386
SUBJECT: GRB 231215A: Swift-BAT refined analysis
DATE:    23/12/17 04:59:08 GMT
FROM:    Takanori Sakamoto at AGU <tsakamoto@phys.aoyama.ac.jp>

S. D. Barthelmy (GSFC), P. D'Avanzo (INAF-OAB), H. A. Krimm (NSF),
S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),
M. Moss (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 231215A (trigger #1202522)
(D'Avanzo, et al., GCN Circ. 35343).  The BAT ground-calculated position is
RA, Dec = 9.730, 57.634 deg which is
   RA(J2000)  =  00h 38m 55.1s
   Dec(J2000) = +57d 38' 00.8"
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 6%.
 The mask-weighted light curve shows a structure of several overlapping pulses.
The emission starts from T-10 s, peaks at T0 and ends at T+20 s.
T90 (15-350 keV) is 20.75 +- 3.69 sec (estimated error including systematics).
 The time-averaged spectrum from T-7.04 to T+19.79 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.01 +- 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+0.18 sec in the 15-150 keV band
is 9.6 +- 1.4 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/1202522/BA/


GRB_name: GRB231216A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35387
SUBJECT: GRB 231216A: Swift-BAT refined analysis
DATE:    23/12/17 05:01:41 GMT
FROM:    Takanori Sakamoto at AGU <tsakamoto@phys.aoyama.ac.jp>

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

Using the data set from T-240 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 231216A (trigger #1202749)
(Sbarrato, et al., GCN Circ. 35378).  The BAT ground-calculated position is
RA, Dec = 39.778, 33.614 deg which is
   RA(J2000)  =  02h 39m 06.6s
   Dec(J2000) = +33d 36' 48.9"
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 59%.

The mask-weighted light curve shows a structure of multiple pulses.
The emission starts from T-5 s, peaks at T0 and ends at T+60 s.
T90 (15-350 keV) is 51.2 +- 3.1 sec (estimated error including systematics).

The time-averaged spectrum from T-1.12 to T+51.39 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.63 +- 0.20.  The fluence in the 15-150 keV band is 1.0 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T-0.51 sec in the 15-150 keV band
is 1.8 +- 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/1202749/BA/


GRB_name: GRB231216A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35388
SUBJECT: GRB 231216A: Swift/UVOT Upper Limits
DATE:    23/12/17 10:03:34 GMT
FROM:    Paul Kuin at MSSL <npkuin@gmail.com>

N. P. M. Kuin (UCL-MSSL) and Sbarrato (INAF-OAB)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 231216A
191 s after the BAT trigger (Sbarrato et al., GCN Circ. 35378).
No optical afterglow consistent with the XRT position was 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

u_FC               191          441          246         >20.2
v                  497          814           58         >18.5
b                  447         1028           63         >20.0
u                  191         1018          432         >20.8
w1                 546          864           58         >19.5
m2                 819          839           19         >18.3
w2                 473          790           58         >19.6

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.082 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB231216A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35389
SUBJECT: GRB 231216A: REM NIR upper limits
DATE:    23/12/17 13:53:14 GMT
FROM:    Matteo Ferro <matteo.ferro@inaf.it>

M. Ferro, R. Brivio, P. D'Avanzo, S. Covino, D. Fugazza (INAF-OAB) on behalf of the REM team, report:

We observed the field of GRB 231216A (Sbarrato et al., GCN 35378) with the REM 60cm robotic telescope located at the ESO Observatory of La Silla (Chile). The observations were carried out in the g,r,i,z, J,H,K bands, starting on 2023 Dec 17 at 00:40:48 UT (i.e. about 6.09 hours after the Swift trigger) and lasted for about 1 hour.
From preliminary analysis, we do not find any source at the XRT position (Sbarrato et al., GCN 35378), down the the following 3 sigma upper limits:

H > 16.7 (Vega; calibrated against the 2MASS catalogue)
at a mid time of t-t0 ~ 6.52 h after the GRB trigger;

K > 16.3 (Vega; calibrated against the 2MASS catalogue)
at a mid time of t-t0 ~ 6.61 h after the GRB trigger.


GRB_name: GRB231216A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35390
SUBJECT: GRB 231216A: AST3-3 YaoAn Optical Upper Limit
DATE:    23/12/17 15:05:33 GMT
FROM:    Tianrui Sun at Purple Mountain Obs,CAS <trsun@pmo.ac.cn>

Tian-Rui Sun (Purple Mountain Observatory), Yan-Long Hua, Mao-Kai Hu, Xue-Feng Wu, Lei Liu, Ke-Lai Meng, Xiao-Yan Li (Nanjing Institute of Astronomical Observation Technology),
Xiang-Yan Yuan, Lifan Wang (TAMU), Xiao-Feng Wang (Tsinghua University), Lei Hu (CMU) report on behalf the AST3 Team:

Following the detection of GRB 231216A by Swift (Sbarrato et al., GCNC 35378),
we use Antarctic Survey Telescope 3-3 at YaoAn Astronomy Observation Station (China, Yunnan) for follow-up.
Our observation started on 2023-12-16T18:44:08 (about 506 seconds after the trigger of BAT (Sbarrato et al., GCNC 35378)). 
No optical source was detected within the XRT error box down to 20.7 mag in the coadded image (total 600s, g-band).


Our non-detection is consistent with the results from the UVOT (Sbarrato et al., GCN 35378), MASTER (Lipunov et al. GCN 35379),
the BOOTES-2/TELMA (Hu et al. GCN 35381), NOT (Daniele B. Malesani et al., GCN 35382) and the T120 at Observatoire de Haute-Provence (Basa et al., GCN 35384)limits.

We thank the staff at YaoAn Astronomy Observation Station for their excellent support.


GRB_name: GRB231216A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35391
SUBJECT: GRB 231216A: Swift-XRT refined Analysis
DATE:    23/12/17 19:18:04 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

B. Sbarufatti (INAF-OAB), C. Salvaggio (INAF-OAB), M. Ferro (INAF-OAB),
J. D. Gropp (PSU), S. Dichiara (PSU), J.A. Kennea (PSU), A.P. Beardmore
(U. Leicester), J.P. Osborne (U. Leicester) and P.A. Evans report on
behalf of the Swift-XRT team:

We have analysed 6.1 ks of XRT data for GRB 231216A, from 115 s to 68.0
ks after the  BAT trigger. The data comprise 8 s in Windowed Timing
(WT) mode (taken while Swift was slewing), with the remainder in Photon
Counting (PC) mode. The refined XRT position is RA, Dec = 39.7727,
+33.5764 which is equivalent to:

RA (J2000): 02 39 05.45
Dec(J2000): +33 34 35.0

with an uncertainty of 3.9 arcsec (radius, 90% confidence).

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.7 (+nan, -nan).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.1 (+0.4, -0.3). The
best-fitting absorption column is  3.2 (+1.7, -1.4) x 10^21 cm^-2, in
excess of the Galactic value of 8.4 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 3.7 x 10^-11 (5.7 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      3.2 (+1.7, -1.4) x 10^21 cm^-2
Galactic foreground: 8.4 x 10^20 cm^-2
Excess significance: 2.8 sigma
Photon index:      2.1 (+0.4, -0.3)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01202749.

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


GRB_name: GRB231215A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35392
SUBJECT: GRB 231215A: Osservatorio Astronomico Nastro Verde upper limit
DATE:    23/12/17 19:52:34 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 231215A detected by Swift Burst Alert Telescope (BAT)(trigger 1202522)
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 16:28 UT of  2023/12/15, after 6,40 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 20 image of 60 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 clear skies.
Start T0+                End T0+       Rlim
16:28:50 UT            17:08:29 UT      20

We did not found any optical counterpart in the error box of the XRTcandidate.
P. D'Avanzo et al. GCN 35343



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



The message may be cited.


GRB_name: GRB231216A
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35393
SUBJECT: GRB 231216A: Swift-XRT refined analysis correction
DATE:    23/12/17 19:53:03 GMT
FROM:    K.L. Page at U Leicester <klp5@leicester.ac.uk>

K.L. Page (U. Leicester) reports on behalf of the Swift-XRT team:

GCN Circular 35391 omitted the uncertainties on the light curve power-law
decay for the Swift-XRT data. The correct value is a decay index of
alpha=0.72 (+0.11, -0.09).

If the light curve continues to decay with a power-law decay index of
0.72, the count rate at T+24 hours will be 4.8 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.8 x 10^-13
(2.8 x 10^-13) erg cm^-2 s^-1.

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


GRB_name: GRB231216A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35394
SUBJECT: GRB 231216A: Osservatorio Astronomico Nastro Verde upper limit
DATE:    23/12/17 20:06:20 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 231216A detected by Swift Burst Alert Telescope (BAT)(trigger 1202749)
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 20:15 UT of  2023/12/16, after 1,40 hours after the GRB trigger, with principal telescope  SC 0.35 f/10 with focal reduced + CCD Sbig ST10 XME
I took 20 image of 60 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 19.5th magnitude  in a sky with light clouds and gusts of wind.
Start T0+                End T0+        Rlim
20:15:25 UT            20:36:38 UT      19.5

We did not found any optical counterpart in the error box of the XRTcandidate.
T. Sbarrato et al. GCN 35378



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



The message may be cited.


GRB_name: GRB231216A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35395
SUBJECT: GRB 231216A: LCOGT Optical Upper Limits
DATE:    23/12/18 14:33:54 GMT
FROM:    Robert Strausbaugh at Eastern Illinois University <rstrausbaugh@eiu.edu>

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

We observed the Swift GRB 231216A (Sbarrato et al., GCN 35378) field with the LCOGT 1-meter Sinistro instrument at the Teide Observatory, Tenerife site, on December 16, from 19:08 to 19:41 UT (corresponding to 0.55 to 1.10 hours after 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 uncataloged source within the XRT error region in either band.  This result is consistent with other optcal upper limits (Hu et al., GCN 35381; Malesani et al., GCN 35382; Sharma et al., GCN 35383; Basa et al., GCN 35384; Kuin et al., GCN 35388; Sun et al., GCN 35390; Ruocco et al., 35394).

The following 5-sigma upper limits are calculated using the PanSTARRS catalog as reference:

r > 22.7
i > 22.1

These magnitudes are not corrected for galactic extinction.


GRB_name: GRB231216A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35396
SUBJECT: GRB 231216A: Nanshan/HMT optical upper limit
DATE:    23/12/18 14:59:03 GMT
FROM:    Dong Xu at NAOC/CAS <dxu@nao.cas.cn>

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

We observed the field of GRB 231216A detected by Swift (Sbarrato et al., GCN 35378) using the HMT-0.5m telescope located at Nanshan, Xinjiang, China. Observations started at 18:42:32 UT on 2023-12-16, i.e., 6.83 mins after the Swift/BAT trigger, and a series of 20, 40, 60, 90, 120, 200 s frames were obtained without any filter.

No optical source is detected in our stacked image at the XRT position (Sbarrato et al., GCN 35378), down to the 3-sigma limiting magnitude of m(r) > 20.2 mag (AB) @ 26.03 mins post-burst, calibrated with the nearby PanSTAR field in the Sloan r-filter. The magnitude is not corrected for Galactic extinction.


GRB_name: GRB231215A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35397
SUBJECT: GRB 231215A: AMI-LA radio detection 
DATE:    23/12/18 15:27:07 GMT
FROM:    Lauren Rhodes at Oxford <lauren.rhodes@physics.ox.ac.uk>

Lauren Rhodes, Rob Fender (Oxford), Dave Green, Dave Titterington (Cambridge) report:
 
We observed the field of the afterglow candidate GRB 231215A (GCN 35343) with the Arcminute Microkelvin Imager Large-Array (AMI-LA) at 15.5 GHz beginning at UT 19:57:45 on 17-Dec-2023 for a total of 4 hours. The flux standard 3c286 was used to calibrate the bandpass response and flux scale of the AMI-LA and J0102+5824 was used as an interleaved complex gain calibrator.

We detect an unresolved radio source at the position of the afterglow candidate as reported in GCN 35345 with a flux density of ~220uJy/beam. 

Further observations are planned. We thank the staff at the Mullard Radio Astronomy Observatory for carrying out these observations and operating the AMI-LA.


GRB_name: GRB231216A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35398
SUBJECT: GRB 231216A: 10.4 m GTC optical upper limit
DATE:    23/12/18 15:52:04 GMT
FROM:    Youdong HU at IAA-CSIC <huyoudong072@hotmail.com>

Y.-D. Hu, R. Sanchez-Ramirez, A. J. Castro-Tirado, S. Guziy, M.D. Caballero-Garcia, S.-Y. Wu, E. Fernandez-Garcia, and I. Perez-Garcia (IAA-CSIC), F. PÃ©rez-Toledo (GTC, IAC), S. B. Pandey (ARIES) and B.-B. Zhang (NJU) on behalf of a larger collaboration, report:

Following the detection of GRB 231216A by Swift (Sbarrato et al., GCNC 35378), we triggered the 10.4m Gran Telescopio de Canarias (GTC) equipped with Optical System for Imaging and low-Intermediate-Resolution Integrated Spectroscopy (OSIRIS) in La Palma (Spain), starting on Dec 16, 20:18 UT (~1.7 h after the trigger). No optical afterglow is indentified within the refined Swift/XRT posiion (Sbarufatti et al. GCNC 35391) which down to i>24.5 mag, which is consistent with these reports from UVOT (Kuin et al., GCNC 35388), MASTER (Lipunov et al. GCNC 35379), NOT (Malesani et al. GCNC 35382), GIT (Sharma et al. GCNC 35383), T120 (Basa et al. GCNC 35384), REM (Ferro et al. GCNC 35389), AST-3 (Sun et al. GCNC 35390), Nastro Verde Observatory (Ruocco et al. GCNC 35394), LCOGT (Strausbaugh et al. GCNC 35395) and Nanshan/HMT (An et al. GCNC 35396).

We thank the staff at GTC for their excellent support.


GRB_name: GRB231216A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35399
SUBJECT: GRB 231216A: optical upper limits from the INAF Asiago Observatory
DATE:    23/12/18 16:58:09 GMT
FROM:    Paolo D'Avanzo at INAF-OAB <pda.davanzo@gmail.com>

A. Reguitti (INAF-OAB / INAF-OAPd), P. D'Avanzo (INAF-OAB), I. Salmaso (INAF -OAPd), E. Cappellaro (INAF -OAPd), 
report on behalf of the CIBO and of the GRAWITA collaborations: 


We observed the field of GRB 231216A (Sbarrato et al., GCN Circ. 35378) from the INAF - Padova Astronomical Observatory 
located in Asiago (Italy) with the 1.8m Copernico telescope starting on 2023-12-16 at 20:24:48 UT (~ 1.8 hours after the burst). 
The observations have been carried out with the AFOSC camera in imaging mode using the r filter. 

No optical afterglow candidate is detected within the XRT error circle (Sbarufatti et al., GCN Circ .35391) down to a 3sigma 
limiting magnitude of r ~ 22.0 (AB; calibrated against the PanSTARRS catalogue).


GRB_name: GRB231214B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35400
SUBJECT: GRB 231214B: Fermi GBM observation
DATE:    23/12/19 08:42:25 GMT
FROM:    Elisabetta Bissaldi at Politecnico and INFN Bari <elisabetta.bissaldi@ba.infn.it>

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


"At 07:53:55.52 UT on 14 December 2023, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 231214B (trigger 724233240 / 231214329),
which was also detected by the Swift/BAT-GUANO (DeLaunay et al. 2023, GCN 35340).

The on-ground calculated location, using the GBM trigger
data, is RA = 137.9, DEC = -13.4 (J2000 degrees,
equivalent to 09h 11m 36, -13d 24'), with a statistical uncertainty
of 6.3 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 78 degrees.

The GBM light curve shows a single weak and structured emission episode
with a duration (T90) of about 39 s (50-300 keV).
The time-averaged spectrum from T0-2 s to T0+39 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is 0.30 +/- 0.19 and
the cutoff energy, parameterized as Epeak, is 148 +/- 15 keV.

The event fluence (10-1000 keV) in this time interval is
(3.02 +/- 0.24)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0 in the 10-1000 keV band
is 1.56 +/- 0.17 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: GRB231216A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35401
SUBJECT: GRB 231216A: GAD Observatory, La Spezia, Italy upper limit
DATE:    23/12/19 11:33:18 GMT
FROM:    Claudio Lopresti <cl3lop@gmail.com>

Claudio Lopresti (Gruppo Astronomia Digitale - GAD Observatory, La Spezia, Italy)

Member of:
UAI/SSV - Unione Astrofili Italiani/Sezione Stelle Variabili, GRB section.
GAD - Gruppo Astronomia Digitale.

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), Unione Astrofili Italiani (UAI)
report:

We imaged the field of GRB 231216A detected by SWIFT(trigger 1202749)
with the telescope LX200 12â€ of GAD Observatory, La Spezia, Italy

The observations with a series of 60 sec exposures started at 2023-12-16 23:14:43 UT, 261 min. after the GRB trigger,with a Shmidt-Cassegrain telescope D=304 mm with reducer F/D=4.75.
at the following position (+/- 2 arcsec):

RA (J2000): 02 39 05.45
Dec(J2000): +33 34 35.0
scope D=300 mm F/D=4.8.

Weather conditions were medium.

We co-added 75 exposures of 60 sec each.

Start T0+      End T0+       R lim
261 min        341 min       18

We did not found any optical counterpart in 02 39 05.45 +33 34 35.0 position and in the error box of the XRT  candidate.
ref.: T. Sbarrato et al. GCN 35378

Magnitudes were estimated with the Gaia EDR3 cat. and
are not corrected for galactic dust extinction.

Reference:
https://www.parcodellestelle.com/

The message may be cited. 


GRB_name: GRB231205A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35402
SUBJECT: GRID detection of GRB 231205A
DATE:    23/12/19 12:34:43 GMT
FROM:    GRID Student Team at Tsinghua University <grid@tsinghua.edu.cn>

Chenyu Wang, Zirui Yang, Longhao Li and Songyu Shen report on behalf of the GRID Collaboration:

GRID-07 reports the detection of the short-duration GRB 231205A, which was also detected by Fermi/GBM and GECAM-B(GCN Circular 35263, 35266).

The event was triggered with GRID on 2023-12-05 at 02:25:11.2 UTC. The measured burst duration (T90) in the 30-2000 keV range is approximately 0.4 Â± 0.1 seconds.

The GRID light curve of this event can be found at https://mirrors.tuna.tsinghua.edu.cn/GRID/data/GRID-GCN/GRB231205A/GRID_231205A_ltcv.pdf.

GRID is a student-led project to monitor the transient gamma-ray sky with multiple detectors onboard different nanosatellites in the era of multi-messenger astronomy. For more information about GRID, please refer to the following references: https://doi.org/10.1007/s10686-019-09636-w and https://doi.org/10.1007/s10686-021-09819-4.


GRB_name: GRB231205B
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35403
SUBJECT: GRID detection of GRB 231205B
DATE:    23/12/19 12:35:19 GMT
FROM:    GRID Student Team at Tsinghua University <grid@tsinghua.edu.cn>

Chenyu Wang, Zirui Yang and Longhao Li report on behalf of the GRID Collaboration:

GRID-03B and GRID-04, onboard the same CubeSat, report the detection of the long-duration GRB 231205B, which was also detected by Swift/BAT, GECAM-B, and AGILE(GCN Circular 35269, 35279, 35295).

The event was triggered with GRID on 2023-12-05 at 16:43:49 UTC. The GRID light curve shows a double-pulse temporal structure. The measured burst duration (T90) in the 30-2000 keV range is approximately 40.2 Â± 3.0 seconds.

The GRID light curve of this event can be found at https://mirrors.tuna.tsinghua.edu.cn/GRID/data/GRID-GCN/GRB231205B/GRID_231205B_ltcv.pdf.

GRID is a student-led project to monitor the transient gamma-ray sky with multiple detectors onboard different nanosatellites in the era of multi-messenger astronomy. For more information about GRID, please refer to the following references: https://doi.org/10.1007/s10686-019-09636-w and https://doi.org/10.1007/s10686-021-09819-4.


GRB_name: GRB231219A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35404
SUBJECT: GRB 231219A: Fermi GBM Final Real-time Localization
DATE:    23/12/19 17:22:54 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 17:12:22 UT on 19 Dec 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231219A (trigger 724698747.778088 / 231219717).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 231.6, Dec = 58.0 (J2000 degrees, equivalent to J2000 15h 26m, 58d 00'), with a statistical uncertainty of 14.2 degrees.

The angle from the Fermi LAT boresight is 21.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231219717/quicklook/glg_skymap_all_bn231219717.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/bn231219717/quicklook/glg_healpix_all_bn231219717.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231219717/quicklook/glg_lc_medres34_bn231219717.gif


GRB_name: GRB231210B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35406
SUBJECT: GRB 231210B: new optical transient detected with the Greenhill Observatory University of Tasmania within the BAT-Swift enhanced position
DATE:    23/12/20 12:59:48 GMT
FROM:    Karelle Siellez at University of Tasmania <karelle.siellez@utas.edu.au>

K. Siellez, B. Emptage, K. Hill, J.-P. Beaulieu (Institute of Astrophysics in Paris / UTas), A. Cole, T. Plunkett report: 

a new optical transient for the GRB 231210B observed with the Harlingten 50cm Telescope starting on 2023-12-11 17:14:35 UT in Sloan r' and g' filters. 

We detect an optical transient at the position RA (J2000) = 06h 23m 05.924s, Dec (J2000) = -48d 19' 11.65", which is not included in the Swift XRT position (Page et al., GCN 35314), but is within the BAT enhanced ground-calculated position (Sakamoto et al., GCN 35322). It has a different position than the optical afterglows already published (GCN 35316, GCN 35323). 

The observations leading to the measurements of the magnitude were made as followed:

  Date     Time             Filter        Exposure (sec)            
-------------------------|-----------|-----------------------------------
2023-12-11 17:14:35.536        r               180                       
2023-12-11 17:17:44.365        r               180                       
2023-12-11 17:20:53.192        r               180      
2023-12-11 17:24:02:021        r               180      
2023-12-11 17:27:10.853        r               180   

On 2023-12-11 we stacked 5 pictures of 180s exposure time for a total of 900s exposure time, with r' filter. We obtain a magnitude of 19.2 +/- 0.1 in r'. 



  Date     Time             Filter        Exposure (sec)            
-------------------------|-----------|-----------------------------------
2023-12-12 11:49:41.012        g'               180                       
2023-12-12 11:52:49.835        g'               180                       
2023-12-12 11:55:58.661        g'               180      
2023-12-12 11:59:07.480        g'               180      
2023-12-12 12:05:25.121        g'               180   

On 2023-12-12 we stacked 5 pictures of 180s exposure time for a total of 900s exposure time, with g' filter. We obtain a magnitude of 20.3 +/- 0.1 in g'. 

On 2023-12-17 we stacked 5 pictures of 180s exposure time for a total of 900s exposure time, with r' filter. We obtain a magnitude of 20.1 +/- 0.1 in r'. 

More data were taken on the days in between and will be released soon.  We encourage the follow up of this optical transient in all wavelengths. 



We acknowledge the traditional custodians of the land upon which we built our telescope: the Palawa / Pakana and Gadigal people. The team wants to thank Caisey Harlingten for his donation and support, the late Dr. John Greenhill who created and pushed forward the development of this optical observatory, as well as Dr. Tony Sprent and Dr. Keith Bolton, who keep supporting and developing the telescopes. 


GRB_name: GRB231220A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35407
SUBJECT: GRB 231220A: Fermi GBM Final Real-time Localization
DATE:    23/12/20 16:20:38 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 16:10:17 UT on 20 Dec 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231220A (trigger 724781422.403544 / 231220674).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 73.4, Dec = 82.3 (J2000 degrees, equivalent to J2000 04h 53m, 82d 17'), with a statistical uncertainty of 5.0 degrees.

The angle from the Fermi LAT boresight is 136.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231220674/quicklook/glg_skymap_all_bn231220674.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/bn231220674/quicklook/glg_healpix_all_bn231220674.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231220674/quicklook/glg_lc_medres34_bn231220674.gif


GRB_name: GRB231220A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35409
SUBJECT: GRB 231220A: Swift/BAT-GUANO arcminute localization of a long burst
DATE:    23/12/20 22:09:23 GMT
FROM:    Samuele Ronchini at PSU <sjs8171@psu.edu>

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

Swift/BAT did not localize GRB 231220A onboard (T0: 2023-12-20T16:10:17.4 UTC, Fermi/GBM GCN 35407).

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 in a 4.096 s analysis time bin with a sqrt(TS) of 28.32, starting at T0 - 1.02 s.
An arcminute localization is found with DeltaLLHOut of 48.29 and a DeltaLLHPeak of 49.13.

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

The BAT position is
RA, Dec = 27.321, 77.897 deg which is
   RA(J2000)  = 01h 49m 17.04s
   Dec(J2000) = +77d 53â€² 49.2â€³
with an estimated uncertainty of 5 arcmin radius.

XRT and UVOT follow-up has been requested.
Results of follow-up observations will be reported in future circulars.

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: GRB231220A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35410
SUBJECT: GRB 231220A: Swift ToO observations
DATE:    23/12/20 23:38:36 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 GUANO GRB 231220A. 
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021638

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 GUANO 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: GRB231220A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35411
SUBJECT: GRB 231220A: Swift-XRT follow-up observations
DATE:    23/12/21 15:25:45 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

C. Salvaggio (INAF-OAB), M. Ferro (INAF-OAB), S. Dichiara (PSU), J.A.
Kennea (PSU), A. Tohuvavohu (U. Toronto), J.P. Osborne (U. Leicester),
K.L. Page (U. Leicester), R. Brivio (INAF-OAB) and P.A. Evans (U.
Leicester) reports on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the GUANO-detected
burst GRB 231220A, collecting 3.6 ks of Photon Counting (PC) mode data
between T0+27.0 ks and T0+39.5 ks. 

No candidate counterpart was detected, with an upper limit of 
2.2Ã—10-3 ct s-1 at the best BAT position (GCN 35409). 

One uncatalogued X-ray source was flagged as spurious 
after manual inspection. 

The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/ToO_GRBs/00021638.

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


GRB_name: GRB231222A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35412
SUBJECT: GRB 231222A: Fermi GBM Final Real-time Localization
DATE:    23/12/22 07:20:32 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 07:09:54 UT on 22 Dec 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231222A (trigger 724921799.613468 / 231222299).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 161.4, Dec = -36.0 (J2000 degrees, equivalent to J2000 10h 45m, -36d 00'), with a statistical uncertainty of 1.2 degrees.

The angle from the Fermi LAT boresight is 91.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231222299/quicklook/glg_skymap_all_bn231222299.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/bn231222299/quicklook/glg_healpix_all_bn231222299.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231222299/quicklook/glg_lc_medres34_bn231222299.gif


GRB_name: GRB231215A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35413
SUBJECT: GRID detection of GRB 231215A
DATE:    23/12/22 09:12:33 GMT
FROM:    GRID Student Team at Tsinghua University <grid@tsinghua.edu.cn>

Chenyu Wang, Zirui Yang and Longhao Li report on behalf of the GRID Collaboration:

GRID-04 reports the detection of the long-duration GRB 231215A, which was also detected by Swift/BAT, AstroSat CZTI, AGILE, Fermi/GBM, Konus-Wind and GRBAlpha(GCN Circular 35343, 35352, 35361, 35369, 35377 and 35380).

The event was triggered with GRID on 2023-12-15 at 09:47:18.5 UTC. The measured burst duration (T90) in the 30-2000 keV range is approximately 17.0 Â± 1.5 seconds.

The time-averaged spectrum of GRID-04 realtime data from T+0 to T+18 sec is best fit by a cutoff power-law model.  The index of the time-averaged spectrum is -0.576(-0.108,+0.114) with a fluence in the 10-1000 keV band is about 5.2488E-05 erg/cm2. All the quoted errors are at the 1-sigma confidence level.

The GRID light curve of this event can be found at https://mirrors.tuna.tsinghua.edu.cn/GRID/data/GRID-GCN/GRB231215A/GRID_231215A_ltcv.pdf. The GRID spectrum of this event can be found at https://mirrors.tuna.tsinghua.edu.cn/GRID/data/GRID-GCN/GRB231215A/GRID_231215A_spec_pl.pdf.

GRID is a student-led project to monitor the transient gamma-ray sky with multiple detectors onboard different nanosatellites in the era of multi-messenger astronomy. For more information about GRID, please refer to the following references: https://doi.org/10.1007/s10686-019-09636-w and https://doi.org/10.1007/s10686-021-09819-4.


GRB_name: GRB231222A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35415
SUBJECT: GRB 231222A: Tiled Swift observations
DATE:    23/12/22 19:25:08 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 231222A. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00118

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: GRB231222B
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35416
SUBJECT: GRB 231222B: Fermi-LAT detection
DATE:    23/12/22 21:31:22 GMT
FROM:    N. Di Lalla at Stanford University <niccolo.dilalla@stanford.edu>

N. Di Lalla (Stanford University), F. Longo (University and INFN, Trieste), A. Holzmann (DF, University of Buenos Aires, Argentina) report on behalf of the Fermi-LAT Collaboration:

On December 22, 2023 Fermi-LAT detected high-energy emission from GRB 231222B, which was also detected by Fermi-GBM (trigger 724922767 / 231222310).

The best LAT on-ground location is found to be

RA, Dec = 251.35, 19.55 (degrees, J2000)

with an error radius of 0.3 deg (90% containment, statistical error only). This was 19 deg from the LAT boresight at the time of the GBM trigger:

T0 = 07:26:02.19 UT.

The data from the Fermi-LAT show a significant increase in the event rate after the GBM trigger that is spatially correlated with the GBM emission with high significance. The photon flux above 100 MeV in the time interval**0-600 s after the GBM trigger is (1.9 +/- 0.7) E-6**ph/cm2/s.

The estimated photon index above 100 MeV is -1.7 +/- 0.3. The highest-energy photon is a 3.6 GeV event which is observed 362 seconds after the GBM trigger.

A Swift ToO has been approved for this burst.

The Fermi-LAT point of contact for this burst is Makoto Arimoto (arimoto@se.kanazawa-u.ac.jp <mailto:arimoto@se.kanazawa-u.ac.jp>)

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: GRB231222B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35418
SUBJECT: GRB 231222B: Fermi GBM Detection
DATE:    23/12/23 00:07:56 GMT
FROM:    Peter Veres at University of Alabama in Huntsville <veresp@gmail.com>

P. Veres (UAH), V. Sharma (NASA-GSFC/UMBC) and R. Hamburg (CNRS/IN2P3) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 07:26:02.19 UT on 22 December 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 231222B (trigger 724922767/231222310).
The GRB was also detected by Fermi LAT (Di Lalla et al, GCN 35416).

The angle from the Fermi LAT boresight is 19 degrees.

The GBM light curve consists of two widely separated pulses with a duration (T90)
of about 121 s (50-300 keV). The time-averaged spectrum
from T0-5.1 to T0+126.0 s is best fit by
a simple power law function with index -1.55 +/- 0.04.

The event fluence (10-1000 keV) in this time interval is
(5.7 +/- 0.6)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+1.7 s in the 10-1000 keV band is 6.0 +/- 0.3 ph/s/cm^2.


A power law function with an exponential
high-energy cutoff fits the spectrum equally well.
The power law index is -1.09 +/- 0.16 and
the cutoff energy, parameterized as Epeak, is 257 +/- 67 keV.


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: GRB231222B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35421
SUBJECT: GRB 231222B: Swift-XRT afterglow detection
DATE:    23/12/23 12:50:08 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

M. Ferro (INAF-OAB), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto),
D.N. Burrows (PSU), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester), A.P. Beardmore (U. Leicester), R. Brivio (INAF-OAB), A.
D'Ai (INAF-IASFPA) and P.A. Evans (U. Leicester) reports on behalf of
the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Fermi/LAT-detected burst GRB 231222B in a series of observations tiled
on the sky. We point out that the burst was improperly named GRB
231222A in GCN Circ 35415, where the tiling was announced. The total
exposure time is 4.1 ks, distributed over 4 tiles; the maximum exposure
at a single sky location was 2.3 ks. The data were collected between
T0+43.2 ks and T0+54.8 ks, and are entirely in Photon Counting (PC)
mode. 

Three uncatalogued X-ray sources are detected, of which one ("Source
1") is believed to be the afterglow. Using 1211 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 = 251.24744, +19.62084 which is equivalent to:

RA (J2000): 16h 44m 59.39s
Dec(J2000): +19d 37' 15.0"

with an uncertainty of 3.3 arcsec (radius, 90% confidence). This
position is 9.3 arcmin from the Fermi/LAT position.  The source has a
mean count rate of 6.0e-02 ct/sec; we cannot determine at the present
time whether it is fading.

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.65 (+0.49, -0.29). The
best-fitting absorption column is  consistent with the Galactic value
of 7.1 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 3.4 x 10^-11 (3.8 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      7 (+/-14) x 10^20 cm^-2
Galactic foreground: 7.1 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.65 (+0.49, -0.29)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00021639.
The results of the full analysis of the tiled XRT observations are
available at https://www.swift.ac.uk/xrt_products/TILED_GRB00118.

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


GRB_name: GRB231222B
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35425
SUBJECT: GRB 231222B: GRBAlpha detection
DATE:    23/12/24 10:24:25 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, L. Szakszonova, 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 231222B (Fermi/GBM detection: GCN 35418; Fermi/LAT detection: GCN 35416; INTEGRAL/SPI-ACS peak detection at 2023-12-22 ~07:26:03 UT) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; arXiv:2302.10048).

The detection was confirmed at the peak time 2023-12-22 07:26:04 UTC. The T90 duration measured by GRBAlpha is 5 s and the overall significance during T90 reaches 6.2 sigma.

The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB231222B_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: GRB231224A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35426
SUBJECT: GRB 231224A: Fermi GBM Final Real-time Localization
DATE:    23/12/24 20:59:57 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 20:49:15 UT on 24 Dec 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231224A (trigger 725143760.994196 / 231224868).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 102.3, Dec = -71.2 (J2000 degrees, equivalent to J2000 06h 49m, -71d 12'), with a statistical uncertainty of 11.9 degrees.

The angle from the Fermi LAT boresight is 24.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231224868/quicklook/glg_skymap_all_bn231224868.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/bn231224868/quicklook/glg_healpix_all_bn231224868.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231224868/quicklook/glg_lc_medres34_bn231224868.gif


GRB_name: GRB231224A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35430
SUBJECT: IPN triangulation of GRB 231224A (short)
DATE:    23/12/27 12:51:08 GMT
FROM:    Dmitry Svinkin at Ioffe Institute <dmitrysvinkin@gmail.com>

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 231224A
(Fermi-GBM detection: The Fermi GBM team, GCN 35426)
was detected by Fermi (GBM trigger 725143760) and
INTEGRAL (SPI-ACS) at about 74956 s UT (20:49:16).

We have triangulated it to a GBM-SPI-ACS annulus centered at
RA(2000)=230.929 deg (15h 23m 43s) Dec(2000)=-83.517 deg (-83d 30' 60"),
whose radius is 32.644 +/- 5.664 deg (3 sigma).

The annulus combined with the Fermi-GBM final position (GCN 35426;
glg_healpix_all_bn231224868_v00) gives ~792 sq. deg (3 sigma) localization region.

A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB231224_T74955/IPN/


GRB_name: GRB231210B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35433
SUBJECT: GRB 231210B: BOOTES-7 optical upper limit
DATE:    23/12/29 07:22:12 GMT
FROM:    Alberto Castro-Tirado at Inst.de Astro. de Andalucia <ajct@iaa.es>

A. J. Castro-Tirado, Y.-D. Hu, E. Fernandez-Garcia, M.D. Caballero-Garcia, R. Sanchez-Ramirez, I. Perez-Garcia, S.-Y. Wu, S. Guziy  (IAA-CSIC Granada), C. Perez del Pulgar, A. Castellon, A. Reina (Univ. de Malaga), B.-B. Zhang (Nanjing Univ.) and A. Maury (Space, San Pedro de Atacama), report:

Following the detection of GRB 231210B by Swift (Page et al., GCNC 35314) and Konus-Wind (Frederiks et al. GCNC 35359), the 0.6m BOOTES-7 robotic telescope at San Pedro de Atacama (Chile) pointed to the burst position on Dec. 21 at 01:32 UT (i.e. ~10.2 days after trigger). Images were gathered in different optical bands. In the co-added r-band image (8 x 300 s, SDSS-r filter), the optical afterglow reported by MASTER (Lipunov et al. GCNC 35313), UVOT (Page et al., GCNC 35314), LCOGT (PÃ©rez-Fournon et al. GCNC 35316), VLT (Saccardi et al. GCNC 35317) and MeerLICHT (de Wet et al. GCNC 35323) is not detected within the enhanced Swift/XRT position (Beardmore et al. GCNC 35318) down to 21.0 mag, which is consistent with the REM results (Ferro et al. GCNC 35333).

Regarding the source reported at the Greenhill Observatory (Siellez et al. GCNC 35406), we cannot clearly identify it since it is blended with a nearby and brighter star 0.4" away. In any case, we notice that this object is present on the DESI catalog and it is far from the enhanced Swift/XRT position and therefore unrelated to GRB 231210B.

BOOTES-7 is the last observatory completing the BOOTES Global Network of robotic telescopes in all the continents (Castro-Tirado 2023, Nat. Astron. 7, 1136), 25 years after the first astronomical station was deployed in south Spain.

We thank the staff at San Pedro de Atacama Celestial Explorations observatory for their excellent support.


GRB_name: GRB231230A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35434
SUBJECT: GRB 231230A: Fermi GBM Final Real-time Localization
DATE:    23/12/30 01:39:51 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 LONG GRB

At 01:29:10 UT on 30 Dec 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231230A (trigger 725592555.052228 / 231230062).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 240.7, Dec = 53.6 (J2000 degrees, equivalent to J2000 16h 02m, 53d 36'), with a statistical uncertainty of 5.2 degrees.

The angle from the Fermi LAT boresight is 157.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231230062/quicklook/glg_skymap_all_bn231230062.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/bn231230062/quicklook/glg_healpix_all_bn231230062.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231230062/quicklook/glg_lc_medres34_bn231230062.gif


GRB_name: GRB231230A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35436
SUBJECT: GRB 231230A: Swift detection of a burst
DATE:    23/12/30 01:44:18 GMT
FROM:    K.L. Page at U Leicester <klp5@leicester.ac.uk>


M. J. Moss (GSFC), C. Gronwall (PSU), J.D. Gropp (PSU),
H. A. Krimm (NSF), A. Y. Lien (U Tampa), K. L. Page (U Leicester) and
M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 01:29:08 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 231230A (trigger=1205319).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 245.197, +58.120 which is 
   RA(J2000) = 16h 20m 47s
   Dec(J2000) = +58d 07' 11"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peaked
structure with a duration of about 30 sec.  The peak count rate
was ~1500 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 01:32:45.0 UT, 216.3 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 245.21706, 58.12324 which is equivalent
to:
   RA(J2000)  = 16h 20m 52.09s
   Dec(J2000) = +58d 07' 23.7"
with an uncertainty of 3.5 arcseconds (radius, 90% containment). This
location is 39 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 (1.31 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 4.3
(+4.82/-3.83) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 145 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
0.015. 

Burst Advocate for this burst is M. J. Moss (mikejmoss3 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: GRB231230A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35437
SUBJECT: GRB 231230A: Prompt enhanced Swift-XRT position
DATE:    23/12/30 02:04:59 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 231230A, we find an
enhanced XRT position of the afterglow: RA, Dec: 245.21382, 58.12618
which is equivalent to:
   RA (J2000)  = 16 20 51.32
   Dec (J2000) = +58 07 34.2
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/1205319.

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: GRB231230A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35439
SUBJECT: GRB 231230A: NOT optical upper limits
DATE:    23/12/30 09:03:02 GMT
FROM:    Zipei Zhu at NAOC <zpzhu@nao.cas.cn>

Z. Zhu, D. Xu (NAOC) report on behalf a larger collaboration:

We observed the position of GRB 231230A (Moss et al., GCN 35436) using the Nordic Optical Telescope equipped with the ALFOSC images. Observations were carried out with the SDSS r and z filters, with an exposure time of 3x300 s and 5x200 s respectively. 

No new objects were dectected in our stacked image within or around the enhanced XRT position (Evans et al., GCN 35437), down to magnitudes r > 23.4 @ T-mid = 4.02 hr and z > 22.7 @ T-mid = 4.32 hr, calibrated with the nearby Pan-STARRS field.


GRB_name: GRB231230A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35440
SUBJECT: GRB 231230A: Swift/UVOT Upper Limits
DATE:    23/12/30 11:25:57 GMT
FROM:    Paul Kuin at MSSL <npkuin@gmail.com>

N. P. M. Kuin (UCL-MSSL) and M. J. Moss (GSFC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 231230A
1511 s after the BAT trigger (Moss et al., GCN Circ. 35436).
No optical 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 initial exposures are:

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

white             1511         1705           39         >18.9
b                 1661         1681           19         >18.5
w1                1612         1632           19         >18.0

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.014 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB231230A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35441
SUBJECT: GRB 231230A: Enhanced Swift-XRT position
DATE:    23/12/30 12:12:48 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 2051 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 231230A, 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 = 245.21436, +58.12396 which is equivalent
to:

RA (J2000): 16h 20m 51.45s
Dec (J2000): +58d 07' 26.2"

with an uncertainty of 2.1 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: GRB231230A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35442
SUBJECT: GRB 231230A: GOTO optical upper limits
DATE:    23/12/30 12:19:49 GMT
FROM:    Amit Kumar at University of Warwick, UK <amitkundu515@gmail.com>

A. Kumar; B. P. Gompertz; G. Ramsay; R. Starling; K. Ulaczyk; K. Ackley; M. J. Dyer; J. Lyman; F. Jimenez-Ibarra; D. O'Neill; D. Steeghs; D. K. Galloway; V. Dhillon; P. O'Brien; K. Noysena; R. Kotak; R. P. Breton; L. K. Nuttall; E. Pall'e and D. Pollacco report on behalf of the GOTO collaboration:

The Gravitational-wave Optical Transient Observer (GOTO, Steeghs et al. 2022) performed a targeted observation in response to Fermi and Swift detected GRB 231230A (Fermi GBM Team, GCN 35434; Moss et al., GCN 35436) at 05:32:28; 05:47:36 and 06:40:25 UT on 2023-12-30 (at respectively ~4.1, 4.3 and 5.2 hours after the trigger). Each set of observations consisted of 4x90s exposures in the GOTO L-band (400-700 nm).

Images were processed immediately after acquisition using the GOTO pipeline. No optical counterpart is detected within the enhanced Swift-XRT position (Evans et al., GCN 35437; Osborne et al., GCN 35441) in any of the three sets of observations up to the 5-sigma limits of L > 18.7, 19.0 and 19.5 magnitudes (AB), respectively. The upper limits are consistent with those reported by Zhu et al., GCN 35439 and Kuin et al., GCN 35440.

Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and are not corrected for Galactic extinction.

GOTO (https://goto-observatory.org) is a network of telescopes that is principally funded by the STFC and operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester and the Instituto de Astrofisica de Canarias (IAC).


GRB_name: GRB231230A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35443
SUBJECT: GRB 231230A: Swift-XRT refined Analysis
DATE:    23/12/30 16:44:29 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

A. Tohuvavohu (U. Toronto), D.N. Burrows (PSU), J. D. Gropp (PSU), K.L.
Page (U. Leicester), A.P. Beardmore (U. Leicester), R. Brivio
(INAF-OAB), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAR) and P.A.
Evans report on behalf of the Swift-XRT team:

We have analysed 9.1 ks of XRT data for GRB 231230A, from 127 s to 41.2
ks after the  BAT trigger. The data comprise 68 s in Windowed Timing
(WT) mode (the first 8 s were taken while Swift was slewing) 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=0.835 (+0.027, -0.028), followed by a break at T+17.4 ks
to an alpha of 2.0 (+/-0.4).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.93 (+/-0.13). The
best-fitting absorption column is  4.0 (+0.7, -0.6) x 10^21 cm^-2, in
excess of the Galactic value of 1.3 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 4.1 x 10^-11 (6.1 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      4.0 (+0.7, -0.6) x 10^21 cm^-2
Galactic foreground: 1.3 x 10^20 cm^-2
Excess significance: 9.9 sigma
Photon index:      1.93 (+/-0.13)

If the light curve continues to decay with a power-law decay index of
2.0, the count rate at T+24 hours will be 5.1 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.1 x
10^-13 (3.1 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/01205319.

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


GRB_name: GRB231230A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35444
SUBJECT: GRB231230A: Fermi GBM Observation
DATE:    23/12/30 18:40:14 GMT
FROM:    Cori Fletcher at USRA <cfletcher@usra.edu>

C. Fletcher (USRA) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 01:29:10.05 UT on 30 December 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB231230A (trigger 725592555/231230062).
which was also detected by Swift-BAT (Moss et al. 2023, GCN 35436).
The Fermi GBM Real-time Localization (GCN 35434) is consistent with the Swift-BAT position.

The angle from the Fermi LAT boresight is 157 degrees.

The GBM light curve consists of multiple spikes with a duration (T90)
of about 17 s (50-300 keV). The time-averaged spectrum
from T0-2.6 to T0+17.9 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -1.2 +/- 0.2 and the cutoff energy,
parameterized as Epeak, is 220 +/- 40 keV.

The event fluence (10-1000 keV) in this time interval is
(6.1 +/- 0.5)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+9.3 s in the 10-1000 keV band is 5 +/- 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: GRB240101A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35448
SUBJECT: GRB 240101A: Swift detection of a burst
DATE:    24/01/01 14:45:57 GMT
FROM:    K.L. Page at U Leicester <klp5@leicester.ac.uk>


S. B. Cenko (GSFC), C. Gronwall (PSU), J.D. Gropp (PSU) and
K. L. Page (U Leicester) report on behalf of the Neil Gehrels Swift
Observatory Team:

The Swift Burst Alert Telescope (BAT) triggered and located GRB 240101A
(trigger=1205708), and Swift has slewed to this burst. The trigger time is
believed to be no earlier than 12:52 UT. Given the loss of some of the TDRSS
notices, we will not have values for T0 or the BAT Position until the
full data have been downloaded, in approximately 1.25 hours (by around 16:05
UT). 

Using promptly downlinked data we find an uncatalogued X-ray source
with an enhanced position: RA, Dec 10.34819, 8.51706 which is
equivalent to:
   RA(J2000)  = 00h 41m 23.57s
   Dec(J2000) = +08d 31' 01.4"
with an uncertainty of 1.9 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 (5.84 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 1.1
(+0.67/-0.52) x 10^22 cm^-2 (90% confidence). 

No afterglow is detected in the initial UVOT data products. 

Burst Advocate for this burst is S. B. Cenko (brad.cenko AT nasa.gov). 
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: GRB240101B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35449
SUBJECT: GRB 240101B: Swift detection of a burst
DATE:    24/01/01 20:42:28 GMT
FROM:    K.L. Page at U Leicester <klp5@leicester.ac.uk>


S. B. Cenko (GSFC), C. Gronwall (PSU), J.D. Gropp (PSU),
H. A. Krimm (NSF), A. Y. Lien (U Tampa) and K. L. Page (U Leicester)
report on behalf of the Neil Gehrels Swift Observatory Team:

At 20:25:39 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 240101B (trigger=1205744).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 352.052, +51.645 which is 
   RA(J2000) = 23h 28m 12s
   Dec(J2000) = +51d 38' 43"
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 20 sec.  The peak count rate
was ~600 counts/sec (15-350 keV), at ~7 sec after the trigger. 

The XRT began observing the field at 20:27:43.2 UT, 123.9 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 352.0966, 51.6379 which is equivalent to:
   RA(J2000)  = 23h 28m 23.18s
   Dec(J2000) = +51d 38' 16.4"
with an uncertainty of 5.1 arcseconds (radius, 90% containment). This
location is 102 arcseconds from the BAT onboard position, within the
BAT error circle. 

The initial flux in the 2.5 s image was 2.19e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 134 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
0.286. 

Burst Advocate for this burst is S. B. Cenko (brad.cenko AT nasa.gov). 
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: GRB240101C
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35451
SUBJECT: GRB 240101C: Fermi GBM Final Localization
DATE:    24/01/02 03:31:02 GMT
FROM:    Bagrat Mailyan at Florida Tech <mbagrat@gmail.com>

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

"At 12:57:23.76 UT on 01 January 2024, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 240101C (trigger 725806648/240101540).

The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 4.73, Dec = 30.46 (J2000 degrees, equivalent to J2000 0h 18m, +30d 27'),
with a statistical uncertainty of 3.33 degrees.

The angle from the Fermi LAT boresight is 69 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240101540/quicklook/glg_skymap_all_bn240101540.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240101540/quicklook/glg_healpix_all_bn240101540.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240101540/quicklook/glg_lc_medres34_bn240101540.gif"


GRB_name: GRB240101A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35452
SUBJECT: GRB 240101A: Enhanced Swift-XRT position
DATE:    24/01/02 04:21:50 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 885 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 240101A, 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 = 10.34841, +8.51582 which is equivalent
to:

RA (J2000): 00h 41m 23.62s
Dec (J2000): +08d 30' 57.0"

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: GRB240101A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35453
SUBJECT: GRB 240101A: KAIT Optical Upper Limit
DATE:    24/01/02 07:21:22 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 Swift GRB 240101A (Cenko et al.,

GCN 35448) starting at 15.57 hours after the burst. A total of

31x60s images were obtained in the clear (roughly R) filters.

We do not detect any optical afterglow candidate within the Enhanced

XRT position error circle (Beardmore et al., GCN 35452), neither in

single image, nor in the co-add images. The typical limiting magnitude

of our single clear image is about 18.5 mag calibrated to the PS1 catalog.


GRB_name: GRB240101B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35454
SUBJECT: GRB 240101B: KAIT Optical Upper Limit
DATE:    24/01/02 07:23:47 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 Swift GRB 240101B (Cenko et al.,

GCN 35449) starting at 7.38 hours after the burst. A total of

31x60s images were obtained in the clear (roughly R) filters.

We do not detect any optical afterglow candidate within the XRT

position error circle (Cenko et al., GCN 35449), neither in single

image, nor in the co-add images. The typical limiting magnitude of

our single clear image is about 18.5 mag calibrated to the PS1 catalog.


GRB_name: GRB240101B
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35455
SUBJECT: GRB 240101B: Enhanced Swift-XRT position
DATE:    24/01/02 10:15:22 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 1510 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 240101B, 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 = 352.09572, +51.63617 which is equivalent
to:

RA (J2000): 23h 28m 22.97s
Dec (J2000): +51d 38' 10.2"

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: GRB240101A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  35456
SUBJECT: GRB 240101A: Swift-XRT refined Analysis
DATE:    24/01/02 11:11:51 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

D.N. Burrows (PSU), J. D. Gropp (PSU), A.P. Beardmore (U. Leicester),
J.P. Osborne (U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri
(INAF-OAR), T. Sbarrato (INAF-OAB), S. Dichiara (PSU) and P.A. Evans
report on behalf of the Swift-XRT team:

We have analysed 6.8 ks of XRT data for GRB 240101A, from 142 s to 57.6
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=1.06 (+0.08, -0.07).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.1 (+/-0.3). The
best-fitting absorption column is  4.3 (+1.8, -1.5) x 10^21 cm^-2, in
excess of the Galactic value of 5.8 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 3.9 x 10^-11 (6.5 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      4.3 (+1.8, -1.5) x 10^21 cm^-2
Galactic foreground: 5.8 x 10^20 cm^-2
Excess significance: 4.1 sigma
Photon index:      2.1 (+/-0.3)

If the light curve continues to decay with a power-law decay index of
1.06, the count rate at T+24 hours will be 1.4 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.6 x
10^-14 (9.3 x 10^-14) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01205708.

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


