# GCN_circulars

GRB_name: GRB210610B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30181
SUBJECT: GRB 210610B: iTelescope optical afterglow observations
DATE:    21/06/10 23:16:52 GMT
FROM:    Filipp Dmitrievich Romanov at Amateur astronomer  <filipp.romanov.27.04.1997@gmail.com>

I observed the field of GRB 201223A (Page et al., GCN Circ. 30170)
with remote telescope T18 (0.32-m f/8.0 reflector + CCD) of
iTelescope.Net in observatory AstroCamp at Nerpio (Spain). Two images
(with exposures 300 seconds, BINx1) were obtained with Astrodon
luminance filter on 2021-06-10 since 21:40:19 UTC (1 hour 48 minutes
52 seconds after the trigger) and since 21:47:05 UTC (1 hour 55
minutes 38 seconds after the trigger).

I clearly detected the optical afterglow with position: RA 16:15:40.38
 Dec +14:23:56.5 (+/- 0.15"). The following magnitudes were measured
from comparison to r magnitudes of nearby stars from Pan-STARRS DR1
catalogue (Chambers et al., 2016): 17.33 (+/- 0.033) and 17.281 (+/-
0.029).

Magnitudes were not corrected for Galactic extinction.

Stacked image available here:
https://www.flickr.com/photos/filipp-romanov/51238249632


GRB_name: GRB210610B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30182
SUBJECT: GRB 210610B: NOT optical observations and tentative redshift
DATE:    21/06/10 23:35:42 GMT
FROM:    Daniele B Malesani at DTU Space  <malesani@space.dtu.dk>

J. P. U. Fynbo (DAWN/NBI), L. Izzo (DARK/NBI), A. de Ugarte Postigo 
(HETH/IAA-CSIC), D. B. Malesani (DTU Space), T. Pursimo (NOT), report on 
behalf of a larger collaboration:

We observed the optical afterglow of GRB 210610B (Page et al., GCN 
30170; Kumar et al., GCN 30174; Rumyantsev et al., GCN 30175; Hu et al., 
GCN 30177; de Wet et al., GCN 30180; Romanov et al., GCN 30181) with the 
Nordic Optical Telescope (NOT) equipped with the ALFOSC imager.

The optical afterglow is well detected, and we measure for it the 
following coordinates (J2000, against the Gaia reference system):

RA = 16:15:40.38
Dec = +14:23:56.6

Our observation was carried out with a clear filter. Calibrating the 
photometry against the r-band magnitudes of nearby Pan-STARRS point 
sources, we get an AB magnitude r = 17.3 +- 0.1, at a mean epoch of 1.69 
hr after the GRB.

Two spectra by 600 s each were obtained using grism #4, covering the 
wavelength range 3600-9400 AA. The continuum is detected at high S/N. 
While there are no strong features, we can identify the Mg II doublet 
and Mg I at a redshift of z = 1.13. We propose this value as the 
tentative redshift of GRB 210610B.


GRB_name: GRB210610B
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30184
SUBJECT: GRB 210610B: correction to GCN 30181
DATE:    21/06/10 23:44:58 GMT
FROM:    Filipp Dmitrievich Romanov at Amateur astronomer  <filipp.romanov.27.04.1997@gmail.com>

Instead "the field of GRB 201223A" meant "the field of GRB 210610B":
this line was copied from my observation of the optical afterglow of
GRB 201223A (GCN Circular #29165) with the same telescope.


GRB_name: GRB210610A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30185
SUBJECT: GRB 210610A: 1.5m OSN optical observation
DATE:    21/06/10 23:49:51 GMT
FROM:    Youdong HU at IAA-CSIC  <huyoudong072@hotmail.com>

T.-R. Sun, Y.-D. Hu, A. Sota, A. J. Castro-Tirado, M. D. Caballero-Garcia, M. A. Castro Tirado and E. Fernandez-Garcia (IAA-CSIC), on behalf of a larger collaboration, report:

Following the detection of GRB 210610A by Swift (Page et al. GCNC 30160), images in BVRI bands were obtained at the 1.5m OSN telescope in Granada (Spain) starting after the twilight as soon as it was possible. In the first I-band 90 s exposure image, the optical afterglow with I = 19.85+-0.18 at 21:12 UT (~6.1 hr after trigger) is clearly seen within the enhanced XRT position (Goad et al. GCNC 30165), which also detected by UVOT/Swift (Page et al. GCNC 30160), MITSuME (Hosokawa et al. GCNC 30161 and Horiuchi et al. GCNC 30169), Xinglong (Xu et al. GCNC 30162), MASTER (Lipunov et al. GCNC 30166) and MeerLICHT (de Wet et al. GCNC 30168). Further observations are ongoing.

We thank the staff at OSN for their excellent support.


GRB_name: GRB210610A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30186
SUBJECT: GRB 210610A: Swift-BAT refined analysis
DATE:    21/06/11 01:02:19 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

S. D. Barthelmy (GSFC),  J. R. Cummings (CPI),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
K. L. Page (U Leicester), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (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 210610A (trigger #1054627)
(Page et al., GCN Circ. 30160).  The BAT ground-calculated position is
RA, Dec = 204.284, 14.476 deg which is
   RA(J2000)  =  13h 37m 08.2s
   Dec(J2000) = +14d 28' 32.5"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 26%.

The mask-weighted light curve shows a structure with two overlapping pulses
that starts at ~T-6 s and ends at ~T+11 s. The two peaks occur at
~T-2 s and ~T0, respectively. T90 (15-350 keV) is 13.62 +- 3.15 sec
(estimated error including systematics).

The time-averaged spectrum from T-5.98 to T+11.35 sec is best fit by
a simple power-law model.  The power law index of the time-averaged
spectrum is 1.41 +- 0.19.  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-0.29 sec in the 15-150 keV band is 2.5 +- 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/1054627/BA/


GRB_name: GRB210610B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30187
SUBJECT: GRB 210610B: SAO RAS optical observations
DATE:    21/06/11 03:16:36 GMT
FROM:    Moskvitin Alexander at SAO RAS  <mosk@sao.ru>

A. S. Moskvitin (SAO RAS) on behalf of the GRB follow-up team report.

We observed the field of the GRB 210610B with the SAO RAS 1-m
telescope Zeiss-1000 + CCD-photometer in BVRc Johnson-Cousins filters.
The observations started on June 10, 20:21:53 UT, since half an hour
after the burst detection by the Swift/BAT (Page et al., GCN #30170).

We clearly detected the OT (Page et al., GCN #30170; Kumar et al.,
GCN #30174; Rumyantsev et al., GCNs #30175, #30178; Hu et al.,
GCN #30177; de Wet et al., GCN #30180; Romanov, GCN #30181;
Fynbo et al., GCN #30182) with the following brightness:

UT_mid     T_mid-T0, h  Exp., s   Rc mag (+/- 0.01 mag)
20:22:03   0.510        20        16.15
20:32:40   0.687        60        16.43
20:48:12   0.946        60        16.75
21:19:20   1.448        60        17.13
21:28:10   1.612        60        17.22
21:53:21   2.032        60        17.26
22:13:03   2.360        60        17.19
22:36:03   2.743       180        17.17
23:04:20   3.215       120        17.20
23:52:38   4.020       120        17.19

The preliminary photometry is based on the USNO-A2.0 star
from GCN #30178 (Rumyantsev et al.).
Magnitudes were not corrected for MW extinction.


GRB_name: GRB210610B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30188
SUBJECT: GRB 210610B: Photometry and phot-redshift from Legacy Survey, PanSTAR, and SDSS
DATE:    21/06/11 03:47:08 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

S.Y. Fu, Z.P. Zhu, D. Xu, X. Liu (NAOC) report on behalf of a larger 
collaboration:

We checked the archives of Legacy Survey (LS), PanSTAR, and SDSS for GRB 
210610B (Page et al., GCN 30170). From the LS, the GRB optical afterglow 
(e.g., Page et al., GCN 30170) is positionally located in a bright 
nucleus, which lies in the south-eastern part of an extended source in 
the direction of NorthWest-SouthEast.

The source has the multi-band photometric magnitudes g = 22.97, r = 
22.87, z = 22.57, and a redshift z_ph = 0.96 +/- 0.44 from LS, and also 
PSF magnitudes g = 24.32 +/- 0.5 , r = 23.09 +/- 0.12, i = 24.33 +/- 
0.47, z = 23.61 +/- 0.69 from PanSTAR. The source is marginally detected 
by SDSS, and we measure its magnitude r ~22.8. The r-band magnitudes 
from three surveys are basically consistent with each other, considering 
difference of photometric methods. The LS's z_ph = 0.96 +/- 0.44 is also 
consistent with the spectroscopic tentative redshift z=1.13 of the GRB 
optical afterglow from the NOT (Fynbo et al., GCN 30182).

We thus think the source is likely the host galaxy of the GRB.


GRB_name: GRB210610B
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30189
SUBJECT: GRB 210610B: Enhanced Swift-XRT position
DATE:    21/06/11 04:07:34 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.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 516 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 210610B, 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 = 243.91883, +14.39881 which is equivalent
to:

RA (J2000): 16h 15m 40.52s
Dec (J2000): +14d 23' 55.7"

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

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

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


GRB_name: GRB210610B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30190
SUBJECT: GRB 210610B: RATIR Optical and NIR Observations
DATE:    21/06/11 05:42:17 GMT
FROM:    Rosa Leticia Becerra Godinez at Inst. de Astronoma,UNAM  <rbecerra@astro.unam.mx>

Rosa L. Becerra (UNAM), Alan M. Watson (UNAM), Nat Butler (ASU), Alexander
Kutyrev (GSFC),
William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI),
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara
(UVI), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), JesÃºs GonzÃ¡lez (UNAM), Carlos RomÃ¡n-ZÃºÃ±iga (UNAM),
Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and
Vicki Toy (UMD) report:

We observed the field of GRB 210610B (K.L. Page, et al., GCN 30170 and J.P.
Osborne, et al., GCN 30189)
with the
Reionization and Transients Infrared Camera (RATIR) on the 1.5m Harold
Johnson Telescope at the Observatorio AstronÃ³mico Nacional on Sierra San
Pedro MÃ¡rtir from 2021/06 11.16 to 2021/06 11.18 UTC (7.91 to 8.38
hours after the BAT trigger), obtaining a total of 0.33 hours exposure
in the r and i bands and 0.15 hours exposure in the Z, Y, J, and H bands.

For a source within the Swift-XRT error circle, in comparison with the
SDSS DR9 and 2MASS catalogs, we obtain the following detections and upper
limits (3-sigma):

  r = 18.03 +/- 0.01
  i = 17.86 +/- 0.01
  Z = 17.65 +/- 0.01
  Y = 17.47 +/- 0.02
  J = 17.55 +/- 0.03
  H = 17.43 +/- 0.03

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.
Further observations are planned.

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


GRB_name: GRB210610A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30191
SUBJECT: GRB 210610A: RATIR Optical and NIR Detection 
DATE:    21/06/11 05:59:57 GMT
FROM:    Alan M Watson at UNAM  <alan@astro.unam.mx>

Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC),
William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI),
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara
(UVI), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), JesÃºs GonzÃ¡lez (UNAM), Carlos RomÃ¡n-ZÃºÃ±iga (UNAM),
Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and
Vicki Toy (UMD) report:

We observed the field of GRB 210610A (Page et al., GCN Circ. 30160) with the 
Reionization and Transients Infrared Camera (RATIR) on the 1.5m Harold 
Johnson Telescope at the Observatorio AstronÃ³mico Nacional on Sierra San 
Pedro MÃ¡rtir from 2021/06 11.18 to 2021/06 11.23 UTC (13.00 to 14.06 
hours after the BAT trigger), obtaining a total of 0.61 hours exposure 
in the r and i bands and 0.25 hours exposure in the Z, Y, J, and H bands.

We detect the afterglow with the following magnitudes and 3-sigma upper limit:

  r = 21.39 +/- 0.06
  i = 21.35 +/- 0.07
  Z = 20.74 +/- 0.10
  Y = 21.05 +/- 0.22
  J = 20.70 +/- 0.25
  H > 20.12

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.

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


GRB_name: GRB210610A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30192
SUBJECT: GRB 210610A: Swift-XRT refined Analysis
DATE:    21/06/11 06:21:16 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

We have analysed 7.1 ks of XRT data for GRB 210610A (Page et al. GCN
Circ. 30160), from 97 s to 45.9 ks after the  BAT trigger. The data are
entirely in Photon Counting (PC) mode. The enhanced XRT position for
this burst was given by Goad et al. (GCN Circ. 30165).

The late-time light curve (from T0+4.1 ks) can be modelled with a
power-law decay with a decay index of alpha=1.05 (+/-0.10).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.84 (+0.12, -0.10). The
best-fitting absorption column is  2.6 (+9.0, -2.6) x 10^21 cm^-2, at a
redshift of 3.54, in addition to the Galactic value of 2.2 x 10^20
cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed)
0.3-10 keV flux conversion factor deduced from this spectrum  is 3.5 x
10^-11 (3.7 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Galactic foreground: 2.2 x 10^20 cm^-2
Intrinsic column:    2.6 (+9.0, -2.6) x 10^21 cm^-2 at z=3.54
Photon index:      1.84 (+0.12, -0.10)

If the light curve continues to decay with a power-law decay index of
1.05, the count rate at T+24 hours will be 9.7 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.4 x
10^-13 (3.6 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/01054627.

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


GRB_name: GRB210610B
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30193
SUBJECT: GRB 210610B: GOTO confirmation of afterglow detection
DATE:    21/06/11 08:16:32 GMT
FROM:    Travis Mong at Monash University  <yik.mong@monash.edu>

Y-L Mong (1); K. Wiersema (2); R. Starling (3); K. Ackley (1);
M. Dyer (4); D. K. Galloway (1); J. Lyman (2); K. Ulaczyk (2);
D. Steeghs (2); V. Dhillon (4); P. O'Brien (3); G. Ramsay (5);
S. Poshyachinda (6); R. Kotak (7); L. Nuttall (8); D. Pollacco (2);
R. Breton (9)

((1) Monash University, (2) Warwick University, (3) University of
Leicester, (4) University of Sheffield, (5) Armagh Observatory &
Planetarium, (6) National Astronomical Research Institute of Thailand, (7)
University of Turku, (8) University of Portsmouth, (9) University of
Manchester) report on behalf of the GOTO collaboration:

We carried out observations with the Gravitational-wave Optical
Transient Observer (GOTO) on La Palma in response to GRB 210610B (Page
et al; GCN 30170). We detect an uncatalogued source consistent with
the OT reported by Swift UVOT (Page et al.; GCN 30170) and other
facilities.

We made a series of 4x90 s exposures using our wide L-band
filter(400-700 nm) beginning around ~4hrs after the trigger, with
midtime of the first observation 23:50:18.136 UT on 10 June 2021.

We detect an uncatalogued source located at (J2000):

RA 16:15:40.369Dec +14:23:57.19

confirming the OT (Page et al.; GCN 30170, Kumar et al.;
GCN 30174, Rumyantsev et al.; GCN 30175, 30178, Hu et al.;
GCN 30177, de Wet et al.; GCN 30180, Romanov; GCN 30181,
Fynbo et al.; GCN 30182, Moskvitin et al.; GCN 30187, Osborne
Et al.; GCN 30189, Becerra et al.; GCN 30190).

We find an equivalent magnitude of g = (17.86 +/- 0.05) mag based
on calibration against PanSTARRS DR1 photometry in ATLAS_REFCAT2
(Tonry et al. 2018).

Observations are continuing.

GOTO is operated at the La Palma observing facilities of the
Universityof Warwick on behalf of a consortium including the
University ofWarwick, Monash University, Armagh Observatory, the
University ofLeicester, the University of Sheffield, the National
AstronomicalResearch Institute of Thailand (NARIT), Turku University,
Portsmouth
University, Manchester University and the Instituto de Astrofisicade
Canarias (IAC) (https://goto-observatory.org)


GRB_name: GRB210610B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30194
SUBJECT: GRB 210610B: Redshift confirmation from GTC
DATE:    21/06/11 08:38:27 GMT
FROM:    Antonio de Ugarte Postigo at IAA-CSIC  <deugarte@iaa.es>

A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), C. Thoene, J.F. Agui Fernandez, M. Blazek, D. A. Kann (all HETH/IAA-CSIC), J. P. U. Fynbo (DAWN/NBI), L. Izzo (DARK/NBI), and D. Garcia Alvarez (GTC) report:

We observed the afterglow of GRB 210610B (Page et al., GCN 30170; Kumar et al., GCN 30174; Rumyantsev et al., GCN 30175; Hu et al., GCN 30177; de Wet et al., GCN 30180; Romanov, GCN 30181; Fynbo et al GCN 30182; Moskvitin et al. GCN 30187; Becerra et al. GCN 30190; Mong et al. GCN 30193) with OSIRIS at the 10.4m GTC telescope, located at Roque de los Muchachos Observatory, in La Palma (Spain). Observation consisted of 3 x 900 s exposures with grism R1000B, covering the range between 3700 and 7800 AA. The first spectrum started at 01:36:20 UT (5.75 hr after the burst).

The spectrum shows a very strong continuum with very weak superposed lines. We detect lines corresponding to FeII, MgII and MgI at a common redshift of z = 1.1345, in agreement with the measurement from the NOT (Fynbo et al. GCN 30182). Additionally, the high SNR allows us to detect a weak intervening system through the identification of MgII at a redshift of z = 0.557. Although the redshift 1.1345 is, strictly speaking, a lower limit, the lack of any further features at higher redshift, especially considering the high SNR of the spectrum, allows us to consider this as the redshift of the GRB.

We note that the features detected at the redshift of the GRB are very weak. We can compare their strength to a sample of long GRB afterglow features using the line strength parameter, following the method of de Ugarte Postigo et al. (2012, A&A 548, A11). For this spectrum we measure LSP = -2.1 +/- 0.8, which implies that the lines are weaker than 99.8% of the sample.


GRB_name: GRB210610B
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30195
SUBJECT: GRB 210610B: AGILE detection
DATE:    21/06/11 09:09:32 GMT
FROM:    Alessandro Ursi at INAF/IAPS  <alessandro.ursi@gmail.com>

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

The AGILE satellite detected the long GRB 210610B at T0 = 2021-06-10
19:51:32 s (UTC), reported by Swift (GCNs #30170, #30189).

The burst is clearly visible in the AGILE scientific ratemeters of the
SuperAGILE (SA; 20-60 keV), MiniCALorimeter (MCAL; 0.4-100 MeV), and
AntiCoincidence (AC; 50-200 keV) detectors. The event lasted about 30 s and
it released a total number of 2340 counts in the SA detector (above a
background rate of 65 Hz), 37190 counts in the MCAL detector (above a
background rate of 1280 Hz), and 110300 counts in the AC detector (above a
background rate of 3800 Hz). The AGILE ratemeter light curves can be found
at http://www.agilescienceapp.it/notices/GRB210610B_AGILE_RM.png .

The event also triggered a partial high time resolution MCAL data
acquisition, from T1 = 2021-06-10 19:51:22.88 s +/- 0.01 (UTC) to T2 =
2021-06-10 19:51:40.27 +/- 0.01 s (UTC), and released 11740 counts in the
detector, above a background rate of 525 Hz. The MCAL light curve can be
found at:
http://www.agilescienceapp.it/notices/073428_GRB_MCAL_550439491.834857.png
. The time-integrated spectrum between T1 and T2 can be fitted in the
energy range 0.4-5 MeV with a power law model with ph.ind. -2.9
-0.33/+0.40. The fit results in a reduced chi-squared of 0.95 (36 d.o.f.)
and a fluence of 8.06e-06 ergs/cm^2 (90% confidence level), in the same
energy range.

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: GRB210610B
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30196
SUBJECT: Konus-Wind detection of GRB 210610B
DATE:    21/06/11 10:33:02 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

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

The long GRB 210610B (Swift detection: Page et al., GCN 30170;
AGILE detection: Ursi et al., GCN 30195)
triggered Konus-Wind (KW) at T0=71488.184 s UT (19:51:28.184).

The burst light curve shows a bright, multi-peaked emission pulse
which starts at ~T0-27 s, and has a total duration of ~100 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/GRB210610_T71488/

As observed by Konus-Wind, the burst had
a fluence of (1.3 Â± 0.1)x10^-4 erg/cm^2 and
a 64-ms peak energy flux, measured from T0 + 10.175 s,
of (1.0 Â± 0.1)x10^-5 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+80.384 s)
is best fit in the 20 keV - 20 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.61 (-0.04,+0.04),
the high energy photon index beta = -2.77 (-0.37,+0.21),
the peak energy Ep = 257 (-14,+15) keV,
chi2 = 97/97 dof.

The spectrum near the peak count rate (measured from T0+8.192
to T0+11.775 s) is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.20 (-0.10,+0.12),
the high energy photon index beta = -3.04 (-0.64,+0.34),
the peak energy Ep = 333 (-24,+23) keV,
chi2 = 60/76 dof.

Assuming the redshift z=1.1345 (de Ugarte Postigo et al., GCN 30194)
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 isotropic energy release E_iso to ~4.6x10^53 erg,
the isotropic luminosity L_iso to ~7.6x10^52 erg/s,
and the rest-frame peak energy of the time-integrated spectrum Ep,z to ~550 keV.
With these values, GRB 210204A is within 68% prediction bands
for both 'Amati' and 'Yonetoku' relations for the sample of >300 long KW GRBs
with known redshifts (Tsvetkova et al., 2021, ApJ, 908, 83),
see http://www.ioffe.ru/LEA/GRBs/GRB210610_T71488/GRB210610B_rest_frame.pdf

All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.


GRB_name: GRB210610A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30197
SUBJECT: Konus-Wind detection of GRB 210610A
DATE:    21/06/11 11:56:36 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

D. Frederiks, S. Golenetskii, A.Lysenko, D. Svinkin,
A. Ridnaya, A. Tsvetkova,  M. Ulanov, and T. Cline, report:

The long GRB 210610A (Swift-BAT detection: Page et al., GCN 30160; Barthelmy et al., GCN 30186),
T0 (BAT) = 15:03:43/387, was detected by Konus-Wind (KW) in the waiting mode.

A Bayesian block analysis of the KW waiting mode data in the 20-400 keV band
reveals a ~8 sigma count rate increase over background in the interval
from ~T0(BAT)-2 s to ~T0(BAT)+4 s.
The KW light curve of this burst is available
at http://www.ioffe.ru/LEA/GRBs/GRB210610A/

Modeling the KW 3-channel spectrum
by a power law with exponential cutoff (CPL) model
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
yields alpha = -0.17(-0.83,+1.15) and Ep = 148(-63,+87) keV.

In the 10 keV -10 MeV band, the total burst fluence is (1.3 Â± 0.5)x10^-6 erg/cm^2,
and the 2.944 s peak energy flux is (2.7 Â± 0.8)x10^-7 erg/cm^2.

Assuming the redshift z=3.54 (Zhu et al., GCN 30164)
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 isotropic energy release E_iso to ~3.5x10^52 erg,
the isotropic luminosity L_iso to ~3.3x10^52 erg/s,
and the rest-frame peak energy of the time-integrated spectrum Ep,z to ~670 keV.
With these values, GRB 210610A is within 90% prediction bands for
for the 'Amati' relation for the sample of >300 long KW GRBs
with known redshifts (Tsvetkova et al., 2021, ApJ, 908, 83),
see http://www.ioffe.ru/LEA/GRBs/GRB210610A/GRB210610A_rest_frame.pdf

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


GRB_name: GRB210610B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30198
SUBJECT: GRB 210610B: University of Siena Observatory optical photometry of the afterglow
DATE:    21/06/11 14:25:00 GMT
FROM:    Simone Leonini at Monarrenti Obs  <s.leonini@iol.it>

Alessandro Marchini, Andrea Lorini (University of Siena Observatory, Siena,
Italy), Simone Leonini (Montarrenti Observatory, Sovicille (SI), Italy),
Giacomo Bonnoli (IAA-CSIC, Granada, Spain) report:

We observed the field of GRB 210610B (Swift trigger 1054681, K.L. Page et al., GCN Circ. 30170) with the 0.3 m telescope  at University of Siena Observatory (Siena, Italy, K54). The GRB was extensively observed at all wavelengths, including optical photometry from many observatories (see e.g GCN Circulars 30173, 30174, 30175, 30176, 30177, 30178, 30180, 30181, 30185, 30187, 30188, 30190, 30191, 30193).

Our observations began under good weather conditions at 2021-06-10 20:37:53 UT (~0.75 h after GRB onset) with a series of 300s CCD exposures in the Rc filter, that were later added in groups of four for the photometry and further analysis.
The optical afterglow was clearly detected at a sky position in agreement with the UVOT astrometry reported in GCN Circ. 30170.
Our data cover continuously almost 6 hours of observations until the field set below the dome horizon. 

The preliminary Rc-band photometry was calibrated with stars from the APASS10 catalog (Henden et al., 2019) after conversion between the two photometric systems with the simple formula from Dymock & Miles (2009) for the CMC15 catalog: Rc=râ€™-0.22. Measurements are not corrected for galactic extinction. Reported uncertainties are statistical only.

The first and last measurements of our series are reported hereafter:

2021-06-10 h. 20:50 UT JD 2459376.368287, R = 16.83 Â± 0.04
2021-06-11 h. 02:26 UT JD 2459376.601458, R = 17.52 Â± 0.16

The evolution of the brightness is, within the limits of our precision, compatible with a single decay rate with index alpha=0.25 Â± 0.04

Any enquiry on these observations can be addressed either to Alessandro Marchini (marchini@unisi.it) or to Giacomo Bonnoli (bonnoli@iaa.es). 

A brief description of our instrumental setup is available at the official webpage of the Astronomical Observatory of the University of Siena:
https://www.dsfta.unisi.it/en/research/labs/astronomical-observatory


GRB_name: GRB210610B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30199
SUBJECT: GRB 210610B: Fermi GBM detection
DATE:    21/06/11 14:50:39 GMT
FROM:    Christian Malacaria at NASA-MSFC/USRA  <cmalacaria@usra.edu>

C. Malacaria (USRA) and B. Hristov (UAH)
report on behalf of the Fermi GBM Team:

At 19:51:05.05 UT on the 10th of June 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210610B (trigger 645047470 / 210610827),
which was also detected by Swift (Page et al. 2021, GCN 30170).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 63 degrees.

The GBM light curve shows of 3 major peaks
with a duration (T90) of about 55 s (50-300 keV).
Spectral evolution is clear throughout the burst, 
therefore we report the spectrum of the brightest peak.
The time-averaged spectrum of the first peak from T0+25.6s to T0+28.7 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.28 +/- 0.03 and
the cutoff energy, parameterized as Epeak, is 414.3 +/- 11.7 keV.

The event fluence (10-1000 keV) in this time interval is
(1.73 +/- 0.03)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+30.1 s in the 10-1000 keV band
is 27.4 +/- 0.3 ph/s/cm^2.


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

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


GRB_name: GRB210610A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30200
SUBJECT: GRB 210610A: Spectroscopy and redshift confirmation with the Himalayan Chandra Telescope
DATE:    21/06/11 15:28:13 GMT
FROM:    Harsh Kumar at Indian Inst of Tech,Bombay  <harshkosli13@gmail.com>

A. Dutta (IIA), H. Kumar (IITB), D. K. Sahu (IIA), B. Kumar (ARIES), G. C.
Anupama (IIA), V. Bhalerao (IITB), S. Barway (IIA) report on behalf of a
larger Indian collaboration:

We obtained a spectrum of the GRB 210210A detected by Swift-BAT ( K. L.
Page et al., GCN #30160), with the HFOSC instrument mounted on the 2-m
Himalayan Chandra Telescope at the Indian Astronomical Observatory. We
obtained a wavelength coverage of 3800 - 8000 angstrom. We took a 2700
second exposure on 2021 June 10 16:48 (UTC).

The spectrum is continuum-dominated with a broad absorption feature at
~5509 A which we interpret as Lyman alpha (rest-frame wavelength 1216 A) at
a redshift of z=3.5, consistent with the redshift reported by Zhu et al.
(GCN #30164. Other absorption features due to Si II (1307 A), Si IV (1397
A), CIV (1549 A) at the same redshift are also observed. The spectrum has
not been corrected for reddening.

We thank the staff at IAO and CREST, Hosakote, for helping with the
observations. The Indian Astronomical Observatory and CREST are operated by
the Indian Institute of Astrophysics, Bengaluru, India.


GRB_name: GRB210610B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30201
SUBJECT: GRB 210610B: Spectroscopy and redshift confirmation with the Himalayan Chandra Telescope
DATE:    21/06/11 15:33:19 GMT
FROM:    Harsh Kumar at Indian Inst of Tech,Bombay  <harshkosli13@gmail.com>

A. Dutta (IIA), H. Kumar (IITB), D. K. Sahu (IIA), B. Kumar (ARIES), G. C.
Anupama (IIA), V. Bhalerao (IITB), S. Barway (IIA) report on behalf of a
larger Indian collaboration:

We obtained a spectrum of the GRB 210210B detected by Swift-BAT ( K. L.
Page et al., GCN #30170 ), with the HFOSC instrument mounted on the 2-m
Himalayan Chandra Telescope (HCT) at the Indian Astronomical Observatory
(IAO). We obtained a wavelength coverage of 3800 - 8000 angstrom. We took
an 1800 second exposure on 2021 June 10 22:02 (UTC).

The spectrum has a relatively featureless blue continuum with weak
absorption features due to Fe II (rest-frame wavelength 2587, 2600 A), Mg
II (2799 A), Mg I (2853 A) at a redshift of z=1.13. The redshift is
consistent with that reported by Fynbo et al. GCN #30182, Fu et al. GCN
#30188 and A. de Ugarte Postigo et al. GCN #30194. The spectrum has not
been corrected for reddening.

We thank the staff at IAO and CREST, Hosakote, for helping with the
observations. The Indian Astronomical Observatory and CREST are operated by
the Indian Institute of Astrophysics, Bengaluru, India.


GRB_name: GRB210607C
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30202
SUBJECT: GRB 210607C: Insight-HXMT/HE detection
DATE:    21/06/11 15:48:01 GMT
FROM:    Y Q Zhang at IHEP  <yqzhang@ihep.ac.cn>

Y. Q. Zhang, C. Cai, J. C. Liu, Q. Luo, S. Xiao, 
W. C. Xue, Q. B. Yi, C. Zhengï¼ŒY. Huang, C. K. Li, 
G. Li, X. B. Li, J. Y. Liao, X. Y. Song, S. L. Xiong, C. Z. Liu, 
X. F. Li, Z. W. Li, Z. Chang, A. M. Zhang, Y. F. Zhang, 
X. F. Lu, C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), 
T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, 
M. Wu, Y. P. Xu, S. N. Zhang (IHEP), 
report on behalf of the Insight-HXMT team:

At 2021-06-07T21:39:20.72 (T0), Insight-HXMT/HE detected 
GRB 210607C (trigger ID: HEB210607902) in a routine search of the data, 
which also triggered INTEGRAL/SPI-ACS (TrigID 9258).

The Insight-HXMT/HE light curve mainly consists of multiple 
pulses with a duration (T90) of 14.84 s measured from T0-1.77 s. 
The 1-ms peak rate, measured from T0+0.74 s, is 3517 cnts/sec. 
The total counts from this burst is 22622 counts. 
URL_LC: http://twiki.ihep.ac.cn/pub/HXMT/GRBList/HEB210607902_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 
of 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: GRB210610A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30203
SUBJECT: GRB 210610A: KAIT Optical Detection
DATE:    21/06/11 16:47:54 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 the Swift GRB 210610A (Page et al.,

GCN 30160) starting at ~14.22 hours after the Swift trigger (Page et al.

GCN 30160). A total of 30x60s images were obtained in the clear (roughly R)

filters. We detect the optical afterglow (e.g. Page et al., GCN 30160)

in the coadd image with a mag of 21.2 +/- 0.2, calibrated to the

Pan-STARRS1 catalog.


GRB_name: GRB210610B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30204
SUBJECT: GRB 210610B: KAIT Optical Detection
DATE:    21/06/11 17:06:02 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 the Swift GRB 210610B (Page et al.,

GCN 30170) starting at ~10.46 hours after the Swift trigger (Page et al.

GCN 30170). A total of 60x60s images were obtained in the clear (roughly R)

filter. The optical afterglow (e.g. Page et al., GCN 30170) was clearly

detected in each single image. We measured its brightness of 18.07 +/- 0.05

mag at 10.46 hours after burst, and decayed to be 18.27 +/- 0.06 mag at

12.20 hours after burst, calibrated to the Pan-STARRS1 catalog.


GRB_name: GRB210610B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30205
SUBJECT: GRB 210610B: optical afterglow observations
DATE:    21/06/11 17:14:07 GMT
FROM:    Paul Vreeswijk at Radboud U/Nijmegen  <p.vreeswijk@astro.ru.nl>

P.M. Vreeswijk (Radboud) reports on behalf of E. Broens (Mol, Belgium):

â€œI observed the field of GRB 210610B (Page et al., GCN 30170; Kumar et
al., GCN 30174; Rumyantsev et al., GCN 30175; Hu et al., GCN 30177; de
Wet et al., GCN 30180; Romanov et al., GCN 30181, GCN 30182; Fynbo et
al, GCN 30182; Moskvitin, GCN 30187) using a 0.28-meter f7 SCT
telescope with a Moravian G2-1600 CCD camera and Astrodon
Johnson-Cousins BVRcIc filters.
 
Five 180 s exposures were average combined for each filter. In the B
filter the OT was only marginally detected with a SNR ~3.  The
following magnitudes were measured using eight APASS DR9 stars in the
field. The APASS DR9 râ€™ and iâ€™ magnitudes were transformed to Rc and
Ic using the Jester et al. (2009, AJ 130, 873) relations.
 
2021-06-10  23:50:30 UT  Rc  17.20 +/- 0.07
2021-06-11  00:05:37 UT  V   17.74 +/- 0.09
2021-06-11  00:20:20 UT  Ic  16.8  +/- 0.2
2021-06-11  00:36:00 UT  B   18.4  +/- 0.2
2021-06-11  00:51:50 UT  Rc  17.25 +/- 0.08
2021-06-11  01:06:23 UT  V   17.71 +/- 0.09"


GRB_name: GRB210610B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30206
SUBJECT: GRB 210610B: Zwicky Transient Facility afterglow detection
DATE:    21/06/11 18:11:12 GMT
FROM:    Daniel Perley at Liverpool JMU  <d.a.perley@ljmu.ac.uk>

D. A. Perley (LJMU), Y. Yao (Caltech), A. Y. Q. Ho (UC Berkeley), M. 
Bulla (Stockholm/OKC), I. Andreoni (Caltech), M. Coughlin (U. 
Minnesota), and E. Kool (Stockholm/OKC) report:

The Zwicky Transient Facility (ZTF; ATel #11266) observed the location 
of GRB 210610B (Page et al., GCN 30170) during the night of 2021-06-11 
UT as part of the regular operations of the ZTF high-cadence partnership 
survey.  Four separate observations of the field (ZTF field ID 533) were 
obtained between 2021-06-11 05:34:44 and 2021-06-11 08:38:29, two each 
in g-band and r-band.

The associated optical transient (e.g., Page et al., GCN 30170; Kumar et 
al., GCN 30174) was automatically identified by the ZTF image 
subtraction pipeline and assigned the identifier ZTF21abfmpwn.  The 
source was independently flagged as a fast transient candidate by both 
the ZTF fast-transient filter pipeline developed by A. Ho and Y. Yao 
(Perley et al. 2021, arXiv:2103.01968) and by the ZTFReST pipeline 
(Andreoni et al. 2021, arXiv:2104.06352), on the basis of its rapid 
evolution over the course of the night and coincidence with a galaxy in 
Pan-STARRS and Legacy Survey reference imaging.

We provide the following photometry:

MJD           t_GRB(d)     filter   magnitude
59376.2324    0.4050       g        18.49 +/- 0.10
59376.2751    0.4477       r        18.29 +/- 0.07
59376.3206    0.4932       r        18.44 +/- 0.07
59376.3600    0.5326       g        18.81 +/- 0.07

Photometry is as provided by the ZTF alert packets and is 
reference-subtracted.  Magnitudes are AB and are not corrected for 
Galactic extinction.

ZTF is supported by the National Science Foundation under Grant No. 
AST-2034437 and a collaboration including Caltech, IPAC, the Weizmann 
Institute for Science, the Oskar Klein Center at Stockholm University, 
the University of Maryland, Deutsches Elektronen-Synchrotron and 
Humboldt University, the TANGO Consortium of Taiwan, the University of 
Wisconsin at Milwaukee, Trinity College Dublin, Lawrence Livermore 
National Laboratories, and IN2P3, France. Operations are conducted by 
COO, IPAC, and UW.

DisclaimerNone


GRB_name: GRB210610B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30207
SUBJECT: GRB 210610B: Swift-BAT refined analysis
DATE:    21/06/11 19:08:46 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

H. A. Krimm (NSF), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), S. Laha (GSFC/UMBC),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
K. L. Page (U Leicester), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (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 210610B (trigger #1054681)
(Page et al., GCN Circ. 30170).  The BAT ground-calculated position is
RA, Dec = 243.929, 14.398 deg which is
   RA(J2000)  =  16h 15m 42.8s
   Dec(J2000) = +14d 23' 54.5"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 24%.

The mask-weighted light curve shows several overlapping pulses that
start at ~T-12 and end at ~T+140 s. The main peak occurs at ~T+8 s.
T90 (15-350 keV) is 69.38 +- 2.53 sec (estimated error including
systematics).

The time-averaged spectrum from T-12.04 to T+142.47 sec is best fit by
a power law with an exponential cutoff.  This fit gives a photon
index 0.98 +- 0.11, and Epeak of 339.3 +- 218.6 keV (chi squared 27.43
for 56 d.o.f.).  For this model the total fluence in the 15-150 keV band
is 3.6 +- 0.1 x 10^-5 erg/cm2 and the 1-sec peak flux measured from
T+7.95 sec in the 15-150 keV band is 13.5 +- 0.7 ph/cm2/sec.  A fit to
a simple power law gives a photon index of 1.17 +- 0.03 (chi squared 36.54
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/1054681/BA/


GRB_name: GRB210610B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30208
SUBJECT: GRB 210610B: Swift-XRT refined Analysis
DATE:    21/06/11 20:48:28 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

We have analysed 5.8 ks of XRT data for GRB 210610B (Page et al. GCN
Circ. 30170), from 87 s to 81.7 ks after the  BAT trigger. The data
comprise 1.3 ks in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Osborne et al. (GCN Circ. 30189).

The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=1.13 (+0.23, -0.34). At T+133 s  the decay
steepens to an alpha of 1.86 (+0.06, -0.05). The light curve breaks
again at T+397 s to a decay with alpha=0.77 (+0.06, -0.05),  before a
final break at T+1153 s s after which the decay index is 1.105 (+0.023,
-0.022).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.847 (+/-0.022). The
best-fitting absorption column is  4.4 (+/-2.5) x 10^20 cm^-2, at a
redshift of 1.13, in addition to the Galactic value of 3.9 x 10^20
cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index
of 1.92 (+/-0.12) and a best-fitting absorption column of 1.1 (+1.4,
-1.1) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV
flux conversion factor deduced from this spectrum  is 3.4 x 10^-11 (3.9
x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Galactic foreground: 3.9 x 10^20 cm^-2
Intrinsic column:    1.1 (+1.4, -1.1) x 10^21 cm^-2 at z=1.13
Photon index:      1.92 (+/-0.12)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01054681.

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


GRB_name: GRB210605B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30209
SUBJECT: GRB 210605B: Fermi GBM detection
DATE:    21/06/11 20:57:40 GMT
FROM:    Suraj Poolakkil at UAH  <sp0076@uah.edu>

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

"At 14:55:58.08 UT on 5 June 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210605B (trigger 644597763 / 210605622)
which was also detected by the Swift/BAT-GUANO (DeLaunay et al. 2021, GCN
30130)
The Fermi GBM Final Real-time Localization (GCN 30129) is consistent with
the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 19
degrees.

The GBM light curve consists of multiple peaks followed by some
extended emission with a duration (T90) of about 110 s (50-300 keV).
The time-averaged spectrum from T0-3.07 s to T0+113.66 s
is best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.78 +/- 0.08  and
the cutoff energy, parameterized as Epeak, is 150 +/- 11 keV.

The event fluence (10-1000 keV) in this time interval is
(10.12 +/- 0.44)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+26.36 s in the 10-1000 keV band
is 3.3 +/- 0.2 ph/s/cm^2.

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

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


GRB_name: GRB210606A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30210
SUBJECT: GRB 210606A: Fermi GBM detection
DATE:    21/06/11 20:58:26 GMT
FROM:    Suraj Poolakkil at UAH  <sp0076@uah.edu>

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

"At 03:56:02.12 UT on 6 June 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210606A (trigger 644644567 / 210606164)
which was also detected by the Swift/BAT-GUANO (DeLaunay et al. 2021, GCN
30134)
The Fermi GBM Final Real-time Localization (GCN 30131) is consistent with
the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 108
degrees.

The GBM light curve consists of a single peak followed by some
extended emission with a duration (T90) of about 11 s (50-300 keV).
The time-averaged spectrum from T0-4.09 s to T0-1.02 s
is best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.99 +/- 0.22  and
the cutoff energy, parameterized as Epeak, is 195 +/- 62 keV.

The event fluence (10-1000 keV) in this time interval is
(0.845 +/- 0.144)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-2.05 s in the 10-1000 keV band
is 2.5 +/- 0.3 ph/s/cm^2.

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

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


GRB_name: GRB210610A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30211
SUBJECT: GRB 210610A: CAHA 2.2m observations and light-curve behavior
DATE:    21/06/11 20:58:31 GMT
FROM:    Alexander Kann at IAA-CSIC  <kann@iaa.es>

D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC, 
DARK/NBI), J. F. Agui Fernandez, C. C. Thoene, M. Blazek (all 
HETH/IAA-CSIC), A. Fernandez, I. Hermelo, and S. Pedraz (all CAHA) 
report:

We observed the afterglow (Page et al., GCN #30160; Hosokawa et al., 
GCNs #30161, #30169; Xu et a., GCN #30162; Kumar et al., GCN #30163; 
Lipunov et al., GCN #30166; de Wet et al., GCN #30168; Sun et al., GCN 
#30185; Watson et al., GCN #30191; Zheng et al., GCN #30203) of GRB 
210610A, discovered by Swift (Page et al., GCN #30160) and also detected 
by Konus-Wind (Frederiks et al., GCN #30197) at redshift z=3.54 (Zhu et 
al., GCN #30164; Dutta et al., GCN #30200). with CAFOS mounted on the 
2.2m telescope at Calar Alto, Almeria, Spain. We obtained 5 x 180 s in 
Sloan i' before switching to observations of GRB 210610B. After these, 
we obtained 3 x 300 s each in Sloan r' and g'.

The afterglow is detected in individual frames. Stacking the images, we 
measure, against nearby comparison stars from the SDSS catalog (AB mags, 
not corrected for Galactic extinction):

i' = 20.18 +/- 0.04 mag at 0.23677 d;
r' = 20.87 +/- 0.05 mag at 0.36333 d;
g' = 21.92 +/- 0.08 mag at 0.37687 d.

Using our data as well as data given in the GCN Circulars cited above, 
we find that after 0.03 d, the light curve can be described with a 
broken power-law fit, with alpha_1 = 0.84, alpha_2 = 1.24, and t_break = 
0.16 d. Earlier data is brighter than the back-extrapolation of the fit, 
indicating a steeper decay must have taken place.


GRB_name: GRB210610A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30212
SUBJECT: GRB 210610A: CrAO/ZTSH optical observations
DATE:    21/06/11 21:17:06 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

N. Pankov (IKI, HSE), A. Pozanenko (IKI), V. Rumyantsev (CrAO),  S. 
Belkin (IKI, HSE)  report on behalf of IKI GRB FuN:

We observed the GRB 210610A (Page  et al., GCN 30170) with ZTSH 2.6m 
telescope of CrAO observatory starting on June 11 (UT) 19:46:53.  The 
optical afterglow  first reported by UVOT (Page  et al., GCN 30170) is 
clearly detected in each of a single image of 120 exposure in R filter.
Preliminary photometry of the afterglow in the first image is following

Date       UT start   t-T0    Filter Exp.    OT      err
                      (mid, days)       (s)

2021-06-11 19:46:53   0.99683 R      1*120   19.50   0.12

The photometry is based on several nearby USNO-B1.0 (R2) stars
USNO-B1.0 id
USNO_B10-1043-00282648
USNO_B10-1043-00282621


GRB_name: GRB210610B
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30213
SUBJECT: GRB 210610B: CrAO/ZTSH optical observations (correction to the GCN circ. 30212)
DATE:    21/06/11 21:35:58 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

N. Pankov (IKI, HSE), A. Pozanenko (IKI), V. Rumyantsev (CrAO),  S. 
Belkin (IKI, HSE)  report on behalf of IKI GRB FuN:

In the GCN circ. 30212 we we incorrectly reported GRB 210610A instead of 
GRB 210610B. The circular should be read as follows.

We observed the GRB 210610B (Page  et al., GCN 30170) with ZTSH 2.6m 
telescope of CrAO observatory starting on June 11 (UT) 19:46:53.  The 
optical afterglow  first reported by UVOT (Page  et al., GCN 30170) is 
clearly detected in each of a single image of 120 exposure in R filter.
Preliminary photometry of the afterglow in the first image is following

Date       UT start   t-T0    Filter Exp.    OT      err
                      (mid, days)       (s)

2021-06-11 19:46:53   0.99683 R      1*120   19.50   0.12

The photometry is based on nearby USNO-B1.0 (R2) stars
USNO-B1.0 id
USNO_B10-1043-00282648
USNO_B10-1043-00282621


GRB_name: GRB210610A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30214
SUBJECT: GRB 210610A: CrAO/ZTSH optical observations
DATE:    21/06/11 22:36:11 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI, HSE), A. Pozanenko (IKI), V. Rumyantsev (CrAO),  N. 
Pankov (IKI, HSE) report on behalf of IKI GRB FuN:

We observed the GRB 210610A (Page  et al., GCN  30160) with ZTSH 2.6m 
telescope of CrAO observatory on June 10 starting on (UT) 18:29:17, and 
June 11 starting on (UT) 18:53:09.  The optical afterglow  first 
reported by UVOT (Page  et al., GCN 30160) is clearly detected in each 
of a single images in R filter in both epochs.
Preliminary photometry of the afterglow in the first image on June 10, 
and combined image on the June 11 is following

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

2021-06-10 18:29:17   0.14310 R       1*60   19.47   0.12  20.7
2021-06-11 18:53:09   1.16766 R      12*120  22.19   0.17  23.0

The photometry is based on nearby SDSS DR12 stars
SDSS-DR12_id RA DEC B(Lupton transformation) R(Lupton transformation)
J133717.13+142854.9 204.32139900 +14.48192200 17.8777 17.0295
J133703.62+142832.7 204.26512000 +14.47576300 19.2842 17.7239
J133658.05+142404.4 204.24188500 +14.40123200 20.3290 18.3616

The light curve of can be found in 
http://grb.rssi.ru/GRB210610A/GRB210610A_LC.png

Initial power law index  of the light curve in the first epoch is about 
-0.82, and it is steepening between the two epochs down to -1.03 which 
is compatible with broken power-law fit reported by D.A. Kann  et al. 
(GCN 30211).


GRB_name: GRB210610B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30215
SUBJECT: GRB 210610B: CrAO/ZTSH optical observations and light curve
DATE:    21/06/11 23:23:01 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

N. Pankov (IKI, HSE), A. Pozanenko (IKI), V. Rumyantsev (CrAO),  S.
Belkin (IKI, HSE)  report on behalf of IKI GRB FuN:

We observed the GRB 210610B (Page  et al., GCN 30170) with ZTSH 2.6m
telescope of CrAO observatory starting on June 10 (UT) 20:19:24 
(Rumyantsev et al., GCNs 30175, 30178).  The optical afterglow  first 
reported by UVOT (Page  et al., GCN 30170) is clearly detected in each 
of a single image of 10 exposure in each of BVRI filters on June 10. 
Based on our observations on June 10 (B, R - filters) and June 11 
(Pankov et al., GCN 30213) we report the light curve (LC) of the 
afterglow which can be found in

http://grb.rssi.ru/GRB210610B/GRB210610B_LC.png

Initial phase of the LC from 0.02 days and up to 0.07 days can be 
approximated by a single power law with index of -0.9, and after that we 
observe plateau phase at least up to 0.18 days after trigger (see figure 
above).


GRB_name: GRB210610B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30216
SUBJECT: GRB 210610B: Liverpool Telescope optical photometry
DATE:    21/06/11 23:27:49 GMT
FROM:    Daniel Perley at Liverpool JMU  <d.a.perley@ljmu.ac.uk>

D. A. Perley (LJMU) reports:

The 2m robotic Liverpool Telescope observed the location of the optical 
afterglow of GRB 210610B (Page et al., GCN 30170) using the IO:O camera 
on 2021-06-11 UT between 22:45:44 and 22:55:45.  Photometry with 
reference to SDSS secondary standard stars in the field gives the 
following magnitudes:

dt_GRB(d) magnitude
1.12521   u = 20.43 +/- 0.11
1.12103   g = 20.04 +/- 0.05
1.12244   r = 19.81 +/- 0.02
1.12383   i = 19.61 +/- 0.03
1.12694   z = 19.49 +/- 0.06







DisclaimerNone


GRB_name: GRB210610B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30217
SUBJECT: GRB 210610B: ALMA detection
DATE:    21/06/12 00:00:13 GMT
FROM:    Tanmoy Laskar at U of Bath  <tanmoylaskar@gmail.com>

T. Laskar (University of Bath), K. D. Alexander (Northwestern), C.
Kilpatrick (Northwestern), G. Schroeder (Northwestern), W. Fong
(Northwestern), E. Berger (Harvard), R. Margutti (Northwestern), C. G.
Mundell (University of Bath), and P. Schady (University of Bath) report on
behalf of a larger collaboration:

"We observed GRB 210610B (Page et al. GCN 30170) with the Atacama Large
Millimeter/Submillimeter Array (ALMA) beginning on 2021 June 11 at 06:21:02
UT (10.5 hr after the burst) at 90.5 GHz. Preliminary analysis reveals a mm
source with flux density of ~ 0.9 mJy at position:

RA (J2000) = 16:15:40.410 (+/- 0.005)
Dec (J2000) = +014:23:56.70 (+/- 0.01)

consistent with the X-ray position (Osborne et al. GCN 30189) and optical
position (Page et al., GCN 30170; Kumar et al. GCN 30174). Follow-up
observations are planned.

We thank the JAO staff, AoD, P2G, and the entire ALMA team for their help
with these observations."


GRB_name: GRB210610B
Detection_method: VLA Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30218
SUBJECT: GRB 210610B: VLA detection
DATE:    21/06/12 00:02:52 GMT
FROM:    Kate Alexander at Northwestern U  <kate.alexander@northwestern.edu>

K. D. Alexander (Northwestern), T. Laskar (University of Bath), C.
Kilpatrick (Northwestern), G. Schroeder (Northwestern), W. Fong
(Northwestern), E. Berger (Harvard), R. Margutti (Northwestern), C. G.
Mundell (University of Bath), and P. Schady (University of Bath) report on
behalf of a larger collaboration:

We observed GRB 210610B (Page et al. GCN 30170) at a mean frequency of 14.7
GHz with the Karl G. Jansky Very Large Array (VLA; Program 21A-241)
beginning 2021 June 11.22 UT (9.4 hours after the burst). We detect a radio
source with a preliminary flux density of ~0.25 mJy at:

RA (J2000) = 16:15:40.381
Dec (J2000) = +14:23:56.59

with an uncertainty of 0.07 arcsec in each coordinate. This position is
fully consistent with the optical afterglow (Page et al. GCN 30170; Kumar
et al. GCN 30174) and the refined Swift/XRT afterglow position (Osborne et
al. GCN 30189). Additional follow-up observations are planned.

We thank the VLA staff for rapidly approving and executing these
observations.


GRB_name: GRB201228B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30219
SUBJECT: GRB 201228B: Fermi GBM observation
DATE:    21/06/12 00:13:12 GMT
FROM:    Cori Fletcher at USRA  <cfletcher@usra.edu>

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

"At 15:21:45.97 UT on 28 December 2020, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 201228B (trigger 630861710 / 201228640)
which was also detected by the Swift/BAT-GUANO (DeLaunay et al. 2021, GCN 29985)
The Fermi GBM Final Real-time Localization (GCN 29188) is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 39 degrees.

The GBM light curve consists of single peak with a duration (T90) of about 30 s (50-300 keV).
The time-averaged spectrum from T0-1.5 to T0+30.2 s is best fit by a Band function with
Epeak = 49 +/- 14 keV, alpha = 0.8 +/- 1.2, and beta = -1.9 +/- 0.1.

The event fluence (10-1000 keV) in this time interval is (2.199 +/- 0.251)E-06 erg/cm^2.
The 1-sec peak photon flux measured starting from T0+1.8 s in the 10-1000 keV band
is 1.3 +/- 0.2 ph/s/cm^2.

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

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


GRB_name: GRB210610B
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30220
SUBJECT: GRB 210610B: MITSuME Akeno optical observation
DATE:    21/06/12 06:19:18 GMT
FROM:    Ryohei Hosokawa at Tokyo Institute of Technology  <hosokawa@hp.phys.titech.ac.jp>

R. Noto, R. Hosokawa, K. L. Murata, M. Niwano, N. Ito, H. Takamatsu,
Y. Imai, S. Sato, M. Takaku, R. Yamaguchi, Y. Yatsu, and N. Kawai
(TokyoTech) report on behalf of the MITSuME collaboration:

We observed the field of GRB 210610B (Page et al. GCN #30170, Ursi et
al. GCN #30195, Frederiks et al. GCN #30196, Malacaria et al. GCN
#30199) with the optical three color (g', Rc, and Ic) CCD cameras
attached to the MITSuME 50 cm telescope Akeno. The observation with a
series of 60 sec exposures started at 2021-06-11 10:33:20 UT (14.7
hours after Swift BAT trigger). We stacked the images with good
conditions. We detected the afterglow reported previously (Page et al.
GCN #30170, Kumar et al. GCN #30174, Rumyantsev et al. GCN #30175,
Lipunov et al. GCN #30176, Hu et al. GCN #30177, Rumyantsev et al. GCN
#30178, Wet et al. GCN #30180, Romanov et al. GCN #30181, Fynbo et al.
GCN #30182, Moskvitin et al. GCN #30187, Becerra et al. GCN #30190,
Mong et al. GCN #30193, Postigo et al. GCN #30194, Marchini et al. GCN
#30198, Dutta et al. GCN #30201, Zheng et al. GCN #30204, Vreeswijk et
al. GCN #30205, Perley et al. GCN #30206, Pankov et al. GCN #30212,
Pankov et al. GCN #30215, Perley et al. GCN #30216, Laskar et al. GCN
#30217, Alexander et al. GCN #30218)

We measured the magnitudes as follows.
MID-UT T-EXP[sec] measured magnitudes
------------------------------------------------------------------------------------------------
2021-06-11 12:51:05 9780 g'=19.3+/-0.2, Rc=18.9+/-0.1, Ic=18.8+/-0.1
------------------------------------------------------------------------------------------------
T-EXP: Total Exposure time

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


GRB_name: GRB210610B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30221
SUBJECT: GRB210610B: SARA-KP 0.9m Optical Afterglow Detection
DATE:    21/06/12 06:40:48 GMT
FROM:    Samalka Anandagoda at Clemson University  <iananda@g.clemson.edu>

S. Anandagoda, K. Pellegrin, and D. Hartmann report:

We observed the field of GRB 210610B detected by Swift BAT (K. L. Page et al., GCN #30170), BALROG (B. Biltzinger et al., GCN #30171), GIT (H. Kumar et al., GCN #30174), V. Rumyantsev et al., V. Lipunov et al., Hu et al., Romanov, Fynbo et al.,Moskvitin et al. and Becerra et al. using the SARA 0.9m optical telescope located at Kitt Peak, AZ, USA, equipped with the Alta-E6-1105 camera.

Observation started at 04:40:42 UTC on 2021-06-12 and ended at 05:43:44 UTC on 2021-06-12. We obtained a series of 150s exposure frames in the Bessell R filter. We detect the optical afterglow of GRB 210610B at the enhanced Swift-XRT position (Osborne et al. GCN 30189).

The estimated magnitude of the GRB afterglow was 20.35 found by stacking 20 images of 150s each in the Bessell R band filter.

T_start-T0 (hrs)   T_end-T0 (hrs)     Start Date (UTC)    Filter  Magnitude (mag)
----------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------
32:34        33:37         2021-06-12T04:40:42       R     20.35


Photometry is done based on the PanSTARRS catalog.

The Southeastern Association for Research in Astronomy (SARA) consortium operates three telescopes: the 0.9-m SARA-KP at Kitt Peak in Arizona, and the 0.6-m SARA-CT at Cerro Tololo in Chile, and the 1.0-m SARA-RM (formerly the JKT) telescope at Roque de los Muchachos Observatory in the Canary Islands. For more information see: Keel et al. (2016): https://iopscience.iop.org/article/10.1088/1538-3873/129/971/015002 <https://iopscience.iop.org/article/10.1088/1538-3873/129/971/015002>
---------------------------------------------------------------------------------------


GRB_name: GRB210607C
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30223
SUBJECT: GRB 210607C: AstroSat CZTI detection
DATE:    21/06/12 14:03:23 GMT
FROM:    Gaurav Waratkar at IIT,Bombay  <gauravwaratkar@iitb.ac.in>

 P. Sawant (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), S. Gupta
(IUCAA), V. Bhalerao (IITB), D. Bhattacharya (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,
2020, arxiv:2011.07067) showed detection of a long GRB 210607C, which
was also detected by Insight-HXMT/HE (GCN #30202). 

The source was clearly detected in the 20-200 keV energy range. The
light curve showed multiple peaks of emission with the strongest peak at
2021-06-07 21:39:21.5 UT. The measured peak count rate associated with
the burst is 2757 (+90, -98) cts/s above the background in the combined
data of four quadrants, with a total of 22768 (+388, -416) cts. The
local mean background count rate was 469 (+3, -3) cts/s. Using
cumulative rates, we measure a T90 of 18 (+1, -1) s. 

It 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 2021-06-07 21:39:20.1 UT. The
measured peak count rate is 2596 (+99, -112) cts/s above the background
in the combined Veto data of four quadrants, with a total of 18010
(+525, -559) cts. The local mean background count rate was 1507 (+5, -6)
cts/s. We measure a T90 of 14 (+1, -1) s from the cumulative Veto light
curve. 

CZTI GRB detections are reported regularly on the payload site at
http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led
consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC
and PRL. The Indian Space Research Organisation funded, managed and
facilitated the project.


GRB_name: GRB210421B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30225
SUBJECT: GRB 210421B: Fermi GBM detection
DATE:    21/06/12 17:55:20 GMT
FROM:    Joe Mangan at UCD  <joseph.mangan@ucdconnect.ie>

J. Mangan (UCD), R. Dunwoody (UCD), C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

At 10:54:44.812 UT on 21 Apr 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210421B (trigger 640695289 / 210421455)
which was also detected by the Swift/BAT-GUANO (DeLaunay et al. 2021, GCN
29877)
The Fermi GBM Final Real-time Localization (GCN 29870) is consistent with
the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 20.1
degrees.

The GBM light curve consists of a single peak
with a duration (T90) of about 11 s (50-300 keV).
The time-averaged spectrum from T0-1.536 s to T0+9.728 is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.98 +/- 0.11 and
the cutoff energy, parameterized as Epeak, is 1253.00 +/- 500.00 keV

The event fluence (10-1000 keV) in this time interval is
(3.655 +/- 0.225)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-0.384 s in the 10-1000 keV band
is 2.74 +/- 0.26 ph/s/cm^2.

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

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


GRB_name: GRB210610B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30226
SUBJECT: GRB 210610B: optical photometry of afterglow at INASAN/Simeiz
DATE:    21/06/12 19:16:14 GMT
FROM:    Mansur Ibrahimov at INASAN  <mansur@inasan.ru>

M. Ibrahimov, M. Nalivkin, I. Nikolenko (all from INASAN, 
Moscow, Russia) and O. Pons (IGA, Havana, Cuba) report on 
behalf of a larger team:



Using Zeiss 1m telescope and 4K FLI PL16803 CCD of Simeiz 
Obserbatory (Collective Using Center of INASAN), we 
observed the field of GRB 210610B (Page et al., GCN 
30170). 15x120sec images were acquired through Bessel R 
filter on 2021-06-11/00:03:07 UT (midpoint time, 4.18 
hours after the trigger) with a total exposure time of 
1800 sec.



Optical afterglow (for a list of the most full references 
see e.g. Hosokawa et al., GCN 30220 and Anandagoda et al., 
GCN 30221) was clearly seen in all 15 individual R images.



Photometry of the optical afterglow using stacked R-image 
calibrated against USNO-B1 R1-mag of 2 nearby stars, 
resulted in: R = 17.61 +/- 0.02 mag.



Research was supported by Project No. RFMEFI61319X0093 
(Russian Ministry of Science and High Education, Agreement 
No. 075-15-2019-1716 by 2019 Nov 20) and Project No. 
19-29-11013 (Russian Foundation of Fundamental 
Investigation, Agreement No. 19-29-11013\20 by 2021 Jan 
21).


GRB_name: GRB210610B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30227
SUBJECT: GRB 210610B: Continued KAIT Optical Detection
DATE:    21/06/12 20:26:48 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:


We continued observing the optical afterglow of GRB 210610B

(e.g. Page et al., GCN 30170; Zheng & Filippenko, GCN 30204) with

the 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at

Lick Observatory. A total of 30x60s images were obtained in the

clear (roughly R) filter. The optical afterglow was detected in the

coadd image with a mag of 20.0 +/- 0.2 at ~1.44 days after burst,

calibrated to the Pan-STARRS1 catalog.


GRB_name: GRB210610B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30228
SUBJECT: GRB 210610B: optical observations from Burke-Gaffney Observatory and Abbey Ridge Observatory
DATE:    21/06/13 00:40:00 GMT
FROM:    Filipp Dmitrievich Romanov at Amateur astronomer  <filipp.romanov.27.04.1997@gmail.com>

Filipp D. Romanov (Russia) and David J. Lane (Saint Mary's University,
Canada) report:

Filipp Romanov observed optical afterglow of GRB 210610B (Page et al.,
GCN Circ. 30170) remotely using telescopes: 0.61-m f/6.5 Corrected
Dall-Kirkham of Burke-Gaffney Observatory (BGO, Dave Lane is
Observatory Director) and 0.355-m f/6.2 Schmidt-Cassegrain of Abbey
Ridge Observatory (ARO, it is owned by D. Lane) on 2021-06-11.

Two images (with exposures 240 and 300 seconds) were obtained on BGO
with Sloan i' filter; on ARO were obtained two clear (unfiltered)
images (with exposures 840 and 900 seconds) and two images (with
exposures 900 and 840 seconds) with Cousins R filter.

F. Romanov measured following magnitudes of afterglow from comparison
to i' magnitudes of nearby stars from the SDSS Photometric Catalogue
DR12 (Alam et al., 2015) for BGO images and from r' magnitudes for ARO
unfiltered images; from comparison to R magnitudes of nearby stars
from USNO-A2.0 catalogue (Monet et al., 1998) for ARO Rc images:


UTC midtime
of exposure    T_mid-T0, h     Magnitude    Mag. error
-------------------------------------------------------
02:07:55       6.27            17.45  i'    0.12
02:09:15       6.30            17.64  r'    0.03
02:14:20       6.38            17.61  i'    0.08
02:27:12       6.60            17.36  Rc    0.05
02:44:54       6.89            17.78  r'    0.08
03:03:24       7.20            17.50  Rc    0.08
-------------------------------------------------------


Magnitudes were not corrected for Galactic extinction.


Images available here:

http://www.ap.smu.ca/~bgo/sm/id.php?app=0&id=15162

http://aro.abbeyridgeobservatory.ca/sm/id.php?app=0&id=3325

http://www.ap.smu.ca/~bgo/sm/id.php?app=0&id=15163

http://aro.abbeyridgeobservatory.ca/sm/id.php?app=0&id=3326

http://aro.abbeyridgeobservatory.ca/sm/id.php?app=0&id=3327

http://aro.abbeyridgeobservatory.ca/sm/id.php?app=0&id=3328


GRB_name: GRB210610A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30229
SUBJECT: GRB 210610A: SAO RAS optical observations
DATE:    21/06/13 13:22:59 GMT
FROM:    Moskvitin Alexander at SAO RAS  <mosk@sao.ru>

A. S. Moskvitin and O. A. Maslennikova (SAO RAS),
report on behalf of the GRB follow-up team.

We observed the field of the GRB 210610A (Page et al., GCN #30160)
with the SAO RAS 1-m telescope Zeiss-1000 + CCD-photometer in Rc band
on June 11 and 12.

We clearly detected the GRB OT (Page et al., GCN #30160;
Hosokawa et al., GCNs #30161, #30169; Xu et al., GCN #30162;
Kumar et al., GCN #30163; Zhu et al., GCN # 30164; Lipunov et al.,
GCN #30166; de Wet et al., GCN #30168; Horiuchi et al., GCN #30169;
Sun et al., GCN #30185; Watson et al., GCN #30191; Dutta et al.,
GCN #30200; Zheng et al., GCN #30203, Kann et al., GCN #30211;
Belkin et al., GCN #30214) in the stacked frame obtained
on June 11 and marginally detected the object in the stacked frame
obtained on June 12.

Date      UT_start  UT_end    Exp., s   T_mid-T0, d   R mag
June, 11  20:12:02--21:08:03   8 x 300  1.23356       22.43 +/- 0.14
June, 12  19:46:09--21:08:36  12 x 300  2.22477       23.3  +/- 0.3

The preliminary photometry is based on magnitudes of the nearby
SDSS stars (transformed with the Lupton 2005 equations).
The OT magnitudes were not corrected for MW extinction.


GRB_name: GRB210610B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30230
SUBJECT: GRB 210610B: Further SAO RAS optical observations
DATE:    21/06/13 14:58:18 GMT
FROM:    Moskvitin Alexander at SAO RAS  <mosk@sao.ru>

A. S. Moskvitin and O. A. Maslennikova (SAO RAS),
report on behalf of the GRB follow-up team.

We observed the field of the GRB 210610B (Page et al., GCN #30170)
with the SAO RAS 1-m telescope Zeiss-1000 + CCD-photometer in BVRc
Johnson-Cousins filters on June 11 and 12.

The GRB OT is clearly detected in the stacked frames
with the following brightness.

Date     UT_start  UT_end    Exp., s  T_mid-T0, d  R mag
June 11  18:54:36--20:03:45  4 x 300  0.98453      19.33 +/- 0.01
June 11  23:14:36--23:49:13  5 x 300  1.15309      19.62 +/- 0.02
June 12  21:28:37--22:47:50  6 x 300  2.09498      20.67 +/- 0.06

The preliminary photometry is based on the USNO-A2.0 star
from GCN #30178 (Rumyantsev et al.) and previous GCN #30187.
Magnitudes were not corrected for MW extinction.


GRB_name: GRB210610B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30231
SUBJECT: GRB 210610B: iTelescope optical afterglow observations
DATE:    21/06/13 18:36:43 GMT
FROM:    Arto Oksanen at Nyrola Obs., Finland  <oksanen@nyrola.jklsirius.fi>

Markku Nissinen (Taurus Hill Observatory, Varkaus, Finland) and Arto Oksanen 
(Hankasalmi Observatory, Hankasalmi, Finland) report:

We have detected GRB 210610B optical afterglow (Page et al., GCN30170) using 
iTelescope T18 (0.32-m f/8.0 + CCD in AstroCamp at Nerpio, Spain), iTelescope T21 
(0.43-m f/6.8 + f/4.5 focal reducer + CCD in New Mexico Skies at Mayhill, 
New Mexico, USA) and iTelescope T11 (0.50-m f/6.8 + f/4.5 focal reducer + CCD 
in New Mexico Skies at Mayhill, New Mexico, USA). 

We took total of 24 exposures with clear (CR), V and R filters. 

The afterglow was clearly detected with each filter at the position
RA 16:15:40.43 DEC +14:23:57.4.  

The following magnitudes were measured from comparison of a nearby star
(V = 13.97, r'=13.70) from the APASS DR9 catalogue (Henden+, 2016):

------------------------------------------------------------------------------
JD            UTC            Mag    Err   Filter AirMass Telescope Exposure(s)
------------------------------------------------------------------------------
2459376.36806 June 10 20:50  16.79  0.05  CR     1.28    T18       7x60
2459376.37868 June 10 21:05  17.15  0.10  V      1.24    T18       10x60
2459376.64285 June 11 03:25  17.76  0.02  CR     1.29    T21       2x300
2459376.65108 June 11 03:37  17.95  0.12  R      1.26    T11       5x300
------------------------------------------------------------------------------

We used r' reference magnitude for the clear filter and the R filter measurements.


GRB_name: GRB210610A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30232
SUBJECT: GRB 210610A: CAHA 2.2m Second Epoch
DATE:    21/06/13 21:56:50 GMT
FROM:    Alexander Kann at IAA-CSIC  <kann@iaa.es>

D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC, 
DARK/NBI), J. F. Agui Fernandez, C. C. Thoene, M. Blazek (all 
HETH/IAA-CSIC), A. Fernandez-Martin (CAHA), and M. Azzaro (IAA-CSIC)
report:

We re-observed the afterglow (Page et al., GCN #30160; Hosokawa et al., 
GCNs #30161, #30169; Xu et a., GCN #30162; Kumar et al., GCN #30163; 
Lipunov et al., GCN #30166; de Wet et al., GCN #30168; Sun et al., GCN 
#30185; Watson et al., GCN #30191; Zheng et al., GCN #30203; Kann et 
al., GCN #30211; Belkin et al., GCN #30214; Moskvitin et al., GCN 
#30229) of GRB 210610A, discovered by Swift (Page et al., GCN #30160) 
and also detected by Konus-Wind (Frederiks et al., GCN #30197) at 
redshift z = 3.54 (Zhu et al., GCN #30164; Dutta et al., GCN #30200). 
with CAFOS mounted on the 2.2m telescope at Calar Alto, Almeria, Spain. 
We obtained 6 x 600 s exposure in Sloan r'.

Stacking the images, the afterglow is well-detected, and we measure, 
against nearby comparison stars from the SDSS catalog (AB mags, not 
corrected for Galactic extinction):

r' = 22.57 +/- 0.04 mag at 1.27366 d.

This value is in good agreement with the observations of Belkin et al., 
GCN #30214; Moskvitin et al., GCN #30229, as well as the extrapolation 
of the decay found by Kann et al., GCN #30211.


GRB_name: GRB210610A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30233
SUBJECT: GRB 210610A: Fermi GBM observations
DATE:    21/06/14 13:35:12 GMT
FROM:    Peter Veres at UAH  <veresp@gmail.com>

P. Veres (UAH), B. Hristov (UAH) and C. Fletcher (USRA) and C. Meegan
(UAH) report on behalf of the Fermi GBM Team:

"At 15:03:42.75 UT on 10th of June 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210610A (trigger 645030227 / 210610628).

The burst was also detected by the Swift/BAT (Page et al., GCN 30160).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 67 degrees.

The GBM light curve consists of two pulses with a duration (T90) of
about 8 s (50-300 keV). The time-averaged spectrum from T0-3.1 s to
T0+4.6 s is adequately fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.11 +/- 0.15 and the
cutoff energy, parameterized as Epeak, is 247 +/- 74 keV.


The event fluence (10-1000 keV) in this time interval is (1.78 +/-
0.23)E-6 erg/cm^2. The 1-sec peak photon flux measured starting from
T0+0.7 s in the 10-1000 keV band is 3.6 +/- 0.3 ph/s/cm^2.



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

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


GRB_name: GRB210605B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30234
SUBJECT: GRB 210605B: Swift-XRT afterglow detection
DATE:    21/06/14 14:06:06 GMT
FROM:    Aaron Tohuvavohu at U Toronto  <aaron.tohu@gmail.com>

A. D'Ai (INAF-IASFPA), A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU),
D.N. Burrows (PSU), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester), A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAB), T.
Sbarrato (INAF-OAB) and P.A. Evans (U. Leicester) report on behalf of
the Swift-XRT team:

Swift-XRT has conducted further observations of the field of the
Swift/BAT-GUANO detected burst GRB 210605B (James DeLaunay et al. GCN
Circ. 30130). The observations now extend from T0+74.3 ks to T0+734.1
ks. 

Of the sources reported by D'Ai et al. (GCN Circ. 30146), "Source 1" is
fading with 2.5 sigma significance and thus is believed to be the GRB
afterglow.  The position of this source is RA, Dec=15.7456, -6.4290
which is equivalent to:

RA (J2000): 01:02:58.95
Dec(J2000): -06:25:44.3

with an uncertainty of 5.7 arcsec (radius, 90% confidence).  This
position is 2.4 arcmin from the Swift/BAT position. 

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.8 (+0.7, -0.4).

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00021450.
The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/ToO_GRBs/00021450.

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


GRB_name: GRB210610B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30238
SUBJECT: GRB 210610B: REM optical/NIR observations of the afterglow
DATE:    21/06/15 18:34:17 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <pda.davanzo@gmail.com>

P. D'Avanzo, A. Melandri, S. Covino, D. Fugazza, (INAF-OAB) on behalf of the REM team, report:

We observed the field of GRB 210610B (Page et al., GCN Circ. 30170) with the REM 60cm robotic telescope located at the ESO premise of La Silla (Chile). 
The observations were performed starting  on 2021 June 10 at 23:14:12 UT (i.e. 3.38 hours after the burst) and were carried in the g, r, i, z, J, H and K bands. 

The optical/NIR afterglow (Page et al., GCN Circ. 30170) is detected with the following magnitudes: 

g = 17.48 +/-  0.10 
r = 17.02 +/-  0.06
i = 17.30  +/- 0.10
z = 16.13 +/-  0.15 (*)
(AB; calibrated against the Pan-STARRS catalogue)
(*): image affected by fringes

J = 15.94  +/- 0.23 
(Vega; calibrated against the 2MASS catalogue)

at a mid time of t-t0 = 4.01 hours.


GRB_name: GRB210615A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30239
SUBJECT: GRB 210615A: Fermi GBM Final Real-time Localization
DATE:    21/06/15 23:44:11 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM  <do_not_reply@GIOC.nsstc.nasa.gov>

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

At 23:33:53 UT on 15 Jun 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210615A (trigger 645492838.603514 / 210615982).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 342.9, Dec = 62.2 (J2000 degrees, equivalent to J2000 22h 51m, 62d 12'), with a statistical uncertainty of 7.5 degrees.

The angle from the Fermi LAT boresight is 19.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210615982/quicklook/glg_skymap_all_bn210615982.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210615982/quicklook/glg_healpix_all_bn210615982.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210615982/quicklook/glg_lc_medres34_bn210615982.gif


GRB_name: GRB210615A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30240
SUBJECT: Fermi GRB 210615A: Global MASTER-Net observations report 
DATE:    21/06/16 01:16:46 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

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

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

D. Buckley 
(South African Astronomical Observatory),

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

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

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




MASTER-Kislovodsk robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 210615A ( Fermi GBM team, GCN 30239) errorbox  28 sec after notice time and 46 sec after trigger time at 2021-06-15 23:34:39 UT, with upper limit up to  18.9 mag. Observations started at twilight.  The observations began at zenith distance = 31 deg. The sun  altitude  is -15.9 deg. 

MASTER-IAC robotic telescope  located in Spain (IAC Teide Observatory) started inspect of the Fermi GRB 210615A errorbox  147 sec after notice time and 166 sec after trigger time at 2021-06-15 23:36:39 UT, with upper limit up to  18.0 mag. The observations began at zenith distance = 70 deg. The sun  altitude  is -34.6 deg. 

The galactic latitude b =  3 deg., longitude l = 110 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1637915

We obtain a following upper limits.  

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

      51 | 2021-06-15 23:34:39 |   MASTER-Kislovodsk | (22h 50m 35.67s , +60d 35m 40.6s) |   C |    10 | 17.2 |        
      66 | 2021-06-15 23:34:39 |   MASTER-Kislovodsk | (22h 50m 35.67s , +60d 35m 40.5s) |   C |    40 | 17.8 |  Coadd 
      51 | 2021-06-15 23:34:39 |   MASTER-Kislovodsk | (22h 59m 09.46s , +60d 10m 09.8s) |   C |    10 | 17.5 |        
      66 | 2021-06-15 23:34:39 |   MASTER-Kislovodsk | (22h 59m 09.46s , +60d 10m 09.9s) |   C |    40 | 18.1 |  Coadd 
      81 | 2021-06-15 23:35:09 |   MASTER-Kislovodsk | (22h 50m 40.61s , +60d 34m 45.1s) |   C |    10 | 17.1 |        
      81 | 2021-06-15 23:35:09 |   MASTER-Kislovodsk | (22h 59m 14.32s , +60d 09m 18.0s) |   C |    10 | 17.0 |        
     116 | 2021-06-15 23:35:39 |   MASTER-Kislovodsk | (22h 50m 34.88s , +60d 33m 45.6s) |   C |    20 | 17.4 |        
     116 | 2021-06-15 23:35:40 |   MASTER-Kislovodsk | (22h 59m 08.38s , +60d 08m 16.1s) |   C |    20 | 17.9 |        
     161 | 2021-06-15 23:36:19 |   MASTER-Kislovodsk | (22h 50m 40.64s , +60d 34m 00.6s) |   C |    30 | 17.6 |        
     206 | 2021-06-15 23:36:19 |   MASTER-Kislovodsk | (22h 50m 40.64s , +60d 34m 00.6s) |   C |   120 | 18.6 |  Coadd 
     161 | 2021-06-15 23:36:19 |   MASTER-Kislovodsk | (22h 59m 14.13s , +60d 08m 31.8s) |   C |    30 | 18.2 |        
     206 | 2021-06-15 23:36:19 |   MASTER-Kislovodsk | (22h 59m 14.13s , +60d 08m 31.8s) |   C |   120 | 18.9 |  Coadd 
     181 | 2021-06-15 23:36:39 |          MASTER-IAC | (22h 49m 25.66s , +60d 20m 32.2s) |  P| |    30 | 16.8 |        
     181 | 2021-06-15 23:36:39 |          MASTER-IAC | (22h 51m 06.66s , +60d 13m 53.2s) |  P- |    30 | 16.5 |        
     217 | 2021-06-15 23:37:10 |   MASTER-Kislovodsk | (22h 50m 38.66s , +60d 35m 47.0s) |   C |    40 | 17.9 |        
     217 | 2021-06-15 23:37:10 |   MASTER-Kislovodsk | (22h 59m 12.53s , +60d 10m 19.4s) |   C |    40 | 18.2 |        
     236 | 2021-06-15 23:37:29 |          MASTER-IAC | (22h 49m 25.81s , +60d 18m 49.7s) |  P| |    40 | 17.0 |        
     236 | 2021-06-15 23:37:29 |          MASTER-IAC | (22h 51m 06.86s , +60d 12m 09.2s) |  P- |    40 | 16.8 |        
     282 | 2021-06-15 23:38:10 |   MASTER-Kislovodsk | (22h 50m 38.54s , +60d 34m 01.3s) |   C |    50 | 18.1 |        
     282 | 2021-06-15 23:38:10 |   MASTER-Kislovodsk | (22h 59m 11.95s , +60d 08m 34.3s) |   C |    50 | 18.3 |        
     300 | 2021-06-15 23:38:29 |          MASTER-IAC | (22h 49m 29.12s , +60d 20m 25.0s) |  P| |    50 | 16.9 |        
     300 | 2021-06-15 23:38:29 |          MASTER-IAC | (22h 51m 10.37s , +60d 13m 42.8s) |  P- |    50 | 16.8 |        
     357 | 2021-06-15 23:39:20 |   MASTER-Kislovodsk | (22h 50m 40.27s , +60d 35m 32.4s) |   C |    60 | 18.2 |        
     357 | 2021-06-15 23:39:20 |   MASTER-Kislovodsk | (22h 59m 14.04s , +60d 10m 06.0s) |   C |    60 | 18.4 |        
     380 | 2021-06-15 23:39:38 |          MASTER-IAC | (22h 49m 23.54s , +60d 19m 32.3s) |  P| |    70 | 17.3 |        
     380 | 2021-06-15 23:39:38 |          MASTER-IAC | (22h 51m 05.10s , +60d 12m 47.8s) |  P- |    70 | 17.2 |        
     437 | 2021-06-15 23:40:40 |   MASTER-Kislovodsk | (22h 51m 15.54s , +60d 15m 42.6s) |   C |    60 | 17.9 |        
     437 | 2021-06-15 23:40:40 |   MASTER-Kislovodsk | (22h 59m 44.45s , +59d 50m 18.2s) |   C |    60 | 18.0 |        
     517 | 2021-06-15 23:42:01 |   MASTER-Kislovodsk | (22h 38m 53.59s , +62d 10m 54.8s) |   C |    60 | 17.9 |        
     517 | 2021-06-15 23:42:01 |   MASTER-Kislovodsk | (22h 47m 53.18s , +61d 45m 29.7s) |   C |    60 | 18.5 |        
     598 | 2021-06-15 23:43:21 |   MASTER-Kislovodsk | (23h 03m 47.20s , +58d 21m 37.9s) |   C |    60 | 17.8 |        
     598 | 2021-06-15 23:43:21 |   MASTER-Kislovodsk | (23h 11m 50.20s , +57d 56m 15.0s) |   C |    60 | 18.2 |        
     678 | 2021-06-15 23:44:41 |   MASTER-Kislovodsk | (23h 20m 19.53s , +61d 42m 55.7s) |   C |    60 | 18.3 |        
     678 | 2021-06-15 23:44:41 |   MASTER-Kislovodsk | (23h 11m 20.78s , +62d 08m 28.2s) |   C |    60 | 18.1 |        
     758 | 2021-06-15 23:46:01 |   MASTER-Kislovodsk | (23h 01m 13.39s , +64d 02m 58.4s) |   C |    60 | 17.9 |        
     758 | 2021-06-15 23:46:01 |   MASTER-Kislovodsk | (23h 10m 46.23s , +63d 37m 23.1s) |   C |    60 | 18.1 |        
     839 | 2021-06-15 23:47:22 |   MASTER-Kislovodsk | (22h 26m 32.08s , +64d 04m 48.9s) |   C |    60 | 17.9 |        
     839 | 2021-06-15 23:47:22 |   MASTER-Kislovodsk | (22h 36m 07.25s , +63d 39m 26.4s) |   C |    60 | 18.1 |        
     919 | 2021-06-15 23:48:42 |   MASTER-Kislovodsk | (22h 51m 03.43s , +65d 57m 10.2s) |   C |    60 | 17.9 |        
     919 | 2021-06-15 23:48:42 |   MASTER-Kislovodsk | (23h 01m 17.00s , +65d 31m 32.9s) |   C |    60 | 18.2 |        
    1028 | 2021-06-15 23:50:31 |   MASTER-Kislovodsk | (22h 20m 47.37s , +60d 17m 20.6s) |   C |    60 | 18.1 |        
    1028 | 2021-06-15 23:50:31 |   MASTER-Kislovodsk | (22h 29m 18.37s , +59d 52m 00.5s) |   C |    60 | 18.3 |        
    1119 | 2021-06-15 23:52:02 |   MASTER-Kislovodsk | (23h 21m 45.32s , +60d 15m 30.5s) |   C |    60 | 18.0 |        
    1119 | 2021-06-15 23:52:02 |   MASTER-Kislovodsk | (23h 30m 14.48s , +59d 50m 05.2s) |   C |    60 | 18.5 |        
    1199 | 2021-06-15 23:53:23 |   MASTER-Kislovodsk | (22h 34m 47.46s , +58d 23m 14.8s) |   C |    60 | 17.7 |        
    1279 | 2021-06-15 23:54:42 |   MASTER-Kislovodsk | (22h 06m 33.49s , +62d 10m 30.4s) |   C |    60 | 17.9 |        
    1279 | 2021-06-15 23:54:43 |   MASTER-Kislovodsk | (22h 15m 35.28s , +61d 45m 19.5s) |   C |    60 | 18.3 |        
    1440 | 2021-06-15 23:57:23 |   MASTER-Kislovodsk | (22h 51m 19.19s , +60d 15m 11.2s) |   C |    60 | 17.9 |        
    1440 | 2021-06-15 23:57:23 |   MASTER-Kislovodsk | (22h 59m 49.05s , +59d 49m 52.4s) |   C |    60 | 18.0 |        
    1520 | 2021-06-15 23:58:43 |   MASTER-Kislovodsk | (22h 38m 54.90s , +62d 10m 53.6s) |   C |    60 | 17.8 |        
    1520 | 2021-06-15 23:58:43 |   MASTER-Kislovodsk | (22h 47m 55.95s , +61d 45m 34.0s) |   C |    60 | 18.2 |        
    1600 | 2021-06-16 00:00:03 |   MASTER-Kislovodsk | (23h 03m 42.79s , +58d 21m 19.8s) |   C |    60 | 17.6 |        
    1600 | 2021-06-16 00:00:03 |   MASTER-Kislovodsk | (23h 11m 46.02s , +57d 55m 59.4s) |   C |    60 | 17.9 |        
    1680 | 2021-06-16 00:01:23 |   MASTER-Kislovodsk | (23h 11m 24.32s , +62d 10m 39.5s) |   C |    60 | 17.9 |        
    1680 | 2021-06-16 00:01:23 |   MASTER-Kislovodsk | (23h 20m 24.24s , +61d 45m 13.2s) |   C |    60 | 18.0 |        
    1686 | 2021-06-16 00:01:29 |          MASTER-IAC | (23h 25m 53.98s , +63d 47m 39.5s) |   C |    60 | 17.4 |        
    1686 | 2021-06-16 00:01:29 |          MASTER-IAC | (23h 44m 16.20s , +63d 42m 17.7s) |   C |    60 | 17.2 |        
    1760 | 2021-06-16 00:02:43 |   MASTER-Kislovodsk | (23h 01m 03.74s , +64d 03m 55.3s) |   C |    60 | 17.7 |        
    1760 | 2021-06-16 00:02:43 |   MASTER-Kislovodsk | (23h 10m 38.58s , +63d 38m 27.3s) |   C |    60 | 17.9 |        
    1766 | 2021-06-16 00:02:49 |          MASTER-IAC | (23h 17m 38.62s , +65d 40m 44.9s) |   C |    60 | 17.5 |        
    1766 | 2021-06-16 00:02:49 |          MASTER-IAC | (23h 37m 20.66s , +65d 35m 23.4s) |   C |    60 | 17.7 |        
    1840 | 2021-06-16 00:04:03 |   MASTER-Kislovodsk | (22h 26m 26.69s , +64d 05m 20.6s) |   C |    60 | 17.7 |        
    1840 | 2021-06-16 00:04:03 |   MASTER-Kislovodsk | (22h 36m 03.54s , +63d 40m 04.5s) |   C |    60 | 17.7 |        
    1846 | 2021-06-16 00:04:09 |          MASTER-IAC | (22h 03m 38.28s , +65d 43m 05.1s) |   C |    60 | 18.0 |        
    1846 | 2021-06-16 00:04:09 |          MASTER-IAC | (22h 23m 26.09s , +65d 37m 36.2s) |   C |    60 | 17.7 |        
    1927 | 2021-06-16 00:05:30 |          MASTER-IAC | (22h 41m 03.04s , +56d 11m 43.1s) |   C |    60 | 17.2 |        
    1927 | 2021-06-16 00:05:30 |          MASTER-IAC | (22h 55m 39.01s , +56d 06m 14.3s) |   C |    60 | 17.4 |        
    2000 | 2021-06-16 00:06:43 |   MASTER-Kislovodsk | (22h 50m 56.82s , +65d 56m 58.7s) |   C |    60 | 17.6 |        
    2000 | 2021-06-16 00:06:43 |   MASTER-Kislovodsk | (23h 01m 12.19s , +65d 31m 24.1s) |   C |    60 | 17.6 |        
    2007 | 2021-06-16 00:06:50 |          MASTER-IAC | (22h 29m 53.58s , +67d 34m 22.2s) |   C |    60 | 17.6 |        
    2007 | 2021-06-16 00:06:50 |          MASTER-IAC | (22h 51m 13.60s , +67d 28m 54.5s) |   C |    60 | 17.6 |        
    2080 | 2021-06-16 00:08:04 |   MASTER-Kislovodsk | (22h 20m 45.82s , +60d 15m 56.8s) |   C |    60 | 17.8 |        
    2081 | 2021-06-16 00:08:04 |   MASTER-Kislovodsk | (22h 29m 18.49s , +59d 50m 43.6s) |   C |    60 | 17.6 |        
    2087 | 2021-06-16 00:08:10 |          MASTER-IAC | (23h 09m 58.10s , +67d 33m 42.3s) |   C |    60 | 17.7 |        
    2087 | 2021-06-16 00:08:10 |          MASTER-IAC | (23h 31m 14.69s , +67d 28m 18.7s) |   C |    60 | 18.0 |        
    2161 | 2021-06-16 00:09:24 |   MASTER-Kislovodsk | (23h 21m 46.90s , +60d 16m 37.4s) |   C |    60 | 17.6 |        
    2161 | 2021-06-16 00:09:24 |   MASTER-Kislovodsk | (23h 30m 17.75s , +59d 51m 16.0s) |   C |    60 | 17.8 |        
    2167 | 2021-06-16 00:09:30 |          MASTER-IAC | (23h 34m 24.53s , +61d 53m 12.6s) |   C |    60 | 17.5 |        
    2167 | 2021-06-16 00:09:30 |          MASTER-IAC | (23h 51m 38.51s , +61d 47m 42.3s) |   C |    60 | 17.4 |        
    2241 | 2021-06-16 00:10:44 |   MASTER-Kislovodsk | (22h 34m 46.87s , +58d 21m 38.5s) |   C |    60 | 17.2 |        
    2241 | 2021-06-16 00:10:44 |   MASTER-Kislovodsk | (22h 42m 53.14s , +57d 56m 37.1s) |   C |    60 | 17.1 |        
    2246 | 2021-06-16 00:10:49 |          MASTER-IAC | (21h 42m 23.80s , +63d 47m 52.4s) |   C |    60 | 18.0 |        
    2246 | 2021-06-16 00:10:49 |          MASTER-IAC | (22h 00m 51.18s , +63d 42m 16.0s) |   C |    60 | 17.9 |        
    2321 | 2021-06-16 00:12:04 |   MASTER-Kislovodsk | (22h 06m 28.45s , +62d 11m 14.7s) |   C |    60 | 17.4 |        
    2321 | 2021-06-16 00:12:04 |   MASTER-Kislovodsk | (22h 15m 32.79s , +61d 46m 13.9s) |   C |    60 | 17.3 |        
    2326 | 2021-06-16 00:12:09 |          MASTER-IAC | (23h 08m 22.90s , +56d 12m 03.1s) |   C |    60 | 17.4 |        
    2326 | 2021-06-16 00:12:09 |          MASTER-IAC | (23h 22m 59.37s , +56d 06m 30.5s) |   C |    60 | 17.3 |        
    2401 | 2021-06-16 00:13:24 |   MASTER-Kislovodsk | (22h 51m 10.23s , +60d 16m 18.8s) |   C |    60 | 17.3 |        
    2401 | 2021-06-16 00:13:24 |   MASTER-Kislovodsk | (22h 59m 42.44s , +59d 51m 02.7s) |   C |    60 | 17.0 |        
    2407 | 2021-06-16 00:13:30 |          MASTER-IAC | (21h 57m 43.00s , +58d 06m 28.1s) |   C |    60 | 17.9 |        
    2407 | 2021-06-16 00:13:30 |          MASTER-IAC | (22h 13m 08.61s , +58d 00m 51.6s) |   C |    60 | 17.7 |        
    2481 | 2021-06-16 00:14:44 |   MASTER-Kislovodsk | (22h 38m 49.79s , +62d 11m 23.6s) |   C |    60 | 17.2 |        
    2481 | 2021-06-16 00:14:44 |   MASTER-Kislovodsk | (22h 47m 53.15s , +61d 46m 10.7s) |   C |    60 | 17.3 |        
    2486 | 2021-06-16 00:14:49 |          MASTER-IAC | (22h 13m 32.96s , +56d 13m 15.8s) |   C |    60 | 17.3 |        
    2486 | 2021-06-16 00:14:49 |          MASTER-IAC | (22h 28m 12.57s , +56d 07m 38.7s) |   C |    60 | 17.4 |        
    2561 | 2021-06-16 00:16:04 |   MASTER-Kislovodsk | (23h 03m 43.14s , +58d 22m 13.7s) |   C |    60 | 17.0 |        
    2561 | 2021-06-16 00:16:04 |   MASTER-Kislovodsk | (23h 11m 48.75s , +57d 56m 59.0s) |   C |    60 | 17.2 |        
    2566 | 2021-06-16 00:16:09 |          MASTER-IAC | (23h 24m 12.74s , +58d 04m 59.8s) |   C |    60 | 17.6 |        
    2566 | 2021-06-16 00:16:09 |          MASTER-IAC | (23h 39m 34.89s , +57d 59m 27.0s) |   C |    60 | 17.4 |        
    2641 | 2021-06-16 00:17:24 |   MASTER-Kislovodsk | (23h 11m 13.90s , +62d 09m 03.1s) |   C |    60 | 17.2 |        
    2641 | 2021-06-16 00:17:24 |   MASTER-Kislovodsk | (23h 20m 15.56s , +61d 43m 42.7s) |   C |    60 | 17.3 |        
    2648 | 2021-06-16 00:17:31 |          MASTER-IAC | (23h 25m 46.93s , +63d 45m 43.0s) |   C |    60 | 17.5 |        
    2648 | 2021-06-16 00:17:31 |          MASTER-IAC | (23h 44m 09.31s , +63d 40m 15.2s) |   C |    60 | 17.5 |        
    2721 | 2021-06-16 00:18:44 |   MASTER-Kislovodsk | (23h 01m 07.15s , +64d 03m 10.3s) |   C |    60 | 17.0 |        
    2721 | 2021-06-16 00:18:44 |   MASTER-Kislovodsk | (23h 10m 43.56s , +63d 37m 45.6s) |   C |    60 | 17.0 |        
    2728 | 2021-06-16 00:18:51 |          MASTER-IAC | (23h 17m 45.41s , +65d 40m 01.9s) |   C |    60 | 17.5 |        
    2728 | 2021-06-16 00:18:51 |          MASTER-IAC | (23h 37m 28.12s , +65d 34m 35.7s) |   C |    60 | 17.7 |        
    2808 | 2021-06-16 00:20:11 |          MASTER-IAC | (22h 03m 40.63s , +65d 42m 34.3s) |   C |    60 | 18.0 |        
    2808 | 2021-06-16 00:20:11 |          MASTER-IAC | (22h 23m 29.11s , +65d 36m 59.3s) |   C |    60 | 17.8 |        
    2819 | 2021-06-16 00:20:22 |   MASTER-Kislovodsk | (22h 26m 26.42s , +64d 05m 04.3s) |   C |    60 | 17.0 |        
    2819 | 2021-06-16 00:20:22 |   MASTER-Kislovodsk | (22h 36m 04.56s , +63d 39m 53.0s) |   C |    60 | 16.8 |        
    2887 | 2021-06-16 00:21:30 |          MASTER-IAC | (22h 40m 57.54s , +56d 10m 48.7s) |   C |    60 | 17.3 |        
    2887 | 2021-06-16 00:21:30 |          MASTER-IAC | (22h 55m 35.11s , +56d 05m 13.4s) |   C |    60 | 17.5 |        
    2900 | 2021-06-16 00:21:43 |   MASTER-Kislovodsk | (21h 50m 07.59s , +60d 15m 55.4s) |   C |    60 | 17.1 |        
    2900 | 2021-06-16 00:21:43 |   MASTER-Kislovodsk | (21h 58m 41.98s , +59d 50m 52.9s) |   C |    60 | 17.2 |        
    2980 | 2021-06-16 00:23:03 |   MASTER-Kislovodsk | (22h 51m 00.75s , +65d 59m 05.0s) |   C |    60 | 16.7 |        
    2980 | 2021-06-16 00:23:03 |   MASTER-Kislovodsk | (23h 01m 17.86s , +65d 33m 41.3s) |   C |    60 | 16.7 |        
    2989 | 2021-06-16 00:23:12 |          MASTER-IAC | (22h 51m 20.34s , +67d 30m 25.3s) |   C |    60 | 17.6 |        
    3060 | 2021-06-16 00:24:23 |   MASTER-Kislovodsk | (22h 20m 37.44s , +60d 16m 44.7s) |   C |    60 | 16.8 |        
    3060 | 2021-06-16 00:24:23 |   MASTER-Kislovodsk | (22h 29m 10.84s , +59d 51m 34.7s) |   C |    60 | 16.5 |        
    3078 | 2021-06-16 00:24:41 |          MASTER-IAC | (23h 09m 49.93s , +67d 34m 46.8s) |   C |    60 | 17.8 |        
    3078 | 2021-06-16 00:24:41 |          MASTER-IAC | (23h 31m 08.56s , +67d 29m 20.5s) |   C |    60 | 17.9 |        
    3140 | 2021-06-16 00:25:43 |   MASTER-Kislovodsk | (23h 21m 42.60s , +60d 17m 07.1s) |   C |    60 | 16.4 |        
    3140 | 2021-06-16 00:25:43 |   MASTER-Kislovodsk | (23h 30m 13.95s , +59d 51m 48.2s) |   C |    60 | 16.8 |        
    3220 | 2021-06-16 00:27:03 |   MASTER-Kislovodsk | (22h 34m 49.99s , +58d 22m 41.5s) |   C |    60 | 15.9 |        
    3220 | 2021-06-16 00:27:03 |   MASTER-Kislovodsk | (22h 42m 56.88s , +57d 57m 43.2s) |   C |    60 | 16.2 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB210323B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30241
SUBJECT: GRB 210323B: Fermi GBM observation
DATE:    21/06/16 17:23:38 GMT
FROM:    Elisabetta Bissaldi at 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 12:03:33.09 UT on 23 March 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210323B (trigger 638193818/ 210323502),
which was also detected by the Swift/BAT-GUANO (DeLaunay et al. 2021, GCN 29701).
The Fermi GBM Final Real-time Localization is consistent with the Swift position.

The angle from the Fermi LAT boresight
at the GBM trigger time is 10 degrees.

The GBM light curve consists of a weak emission episode
with a duration (T90) of about 14 s (50-300 keV).
The time-averaged spectrum from T0-4.9 s to T0+5.9 s is
adequately fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.94 +/- 0.26 and
the cutoff energy, parameterized as Epeak, is 740 +/- 540 keV.

The event fluence (10-1000 keV) in this time interval is
(2.1 +/- 0.3)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 1.1 +/- 0.2 ph/s/cm^2.


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

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


GRB_name: GRB201008A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30242
SUBJECT: GRB 201008A: Fermi GBM observation
DATE:    21/06/16 17:27:21 GMT
FROM:    Elisabetta Bissaldi at 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 10:37:36.71 UT on 8 October 2020, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 201008A (trigger 623846261 / 201008443),
which was also detected by the Swift/BAT-GUANO (DeLaunay et al. 2020, GCN 28583).
The Fermi GBM Final Real-time Localization is consistent with the Swift position.

The angle from the Fermi LAT boresight
at the GBM trigger time is 60 degrees.

The GBM light curve consists of a multi-peaked emission episode
with a duration (T90) of about 2 s (50-300 keV).
The time-averaged spectrum from T0-0.26 s to T0+2.11 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.80 +/- 0.13 and
the cutoff energy, parameterized as Epeak, is 166 +/- 21 keV.

The event fluence (10-1000 keV) in this time interval is
(1.17 +/- 0.09)E-06 erg/cm^2. The 64-ms peak photon flux measured
starting from T0+1.28 s in the 10-1000 keV band
is 7.3 +/- 1.3 ph/s/cm^2.


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

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


GRB_name: GRB210610B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30243
SUBJECT: GRB 210610B: AbAO optical observations
DATE:    21/06/16 21:40:26 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

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

We observed the GRB 210610B (Page  et al., GCN 30170) with AS-32 
telescope of Abastumani observatory (AbAO) in R-filter on June, 13. The 
optical afterglow  first reported by UVOT (Page  et al., GCN 30170) is 
clearly detected is detected in stacked image. Preliminary photometry of 
the afterglow is following

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


2021-06-13 17:06:46   2.88564  R     72*60   21.25  0.14  22.6


The photometry is based on calibrations stars reported in (Pankov et 
al., GCN 30213).


GRB_name: GRB210610B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30245
SUBJECT: GRB 210610B: CrAO/ZTSH continued optical observations and light curve
DATE:    21/06/16 22:55:29 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

N. Pankov (IKI, HSE), A. Pozanenko (IKI), V. Rumyantsev (CrAO), S. 
Belkin (IKI, HSE)  report on behalf of IKI GRB FuN:

We observed the GRB 210610B (Page  et al., GCN 30170) with ZTSH 2.6m
telescope of CrAO observatory on June 10,11  (Rumyantsev et al., GCNs 
30175, 30178; Pankov et al., GCN 30213) and June 12 - 14.  The optical 
afterglow  first reported by UVOT (Page  et al., GCN 30170) is clearly 
detected in each epochs. Some preliminary photometry is following.

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

2021-06-12 20:54:55   2.0545  R      2*120   20.80   0.10  22.2
2021-06-12 22:41:00   2.1282  R      2*120   20.89   0.10  22.8
2021-06-14 20:40:19   4.0649  R     25*120   21.90   0.11  23.3

The photometry is based on calibrations stars reported in (Pankov et
al., GCN 30213).

Based on our observations in ZTSh on June 10-14, AbAO (Pankov et al., 
GCN 30243) and photometry reported in GCNs we report the light curve of 
the afterglow which can be found in

http://grb.rssi.ru/GRB210610B/GRB210610B_LC.png

After plateau phase lasting up to ~ 0.3 days in R-filter, the LC can be 
approximated by a single power law with index of -1.6.


GRB_name: GRB210610A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30246
SUBJECT: GRB 210610A: Swift/UVOT Detection
DATE:    21/06/17 13:36:23 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <mhs18@psu.edu>

M. H. Siegel (PSU), M. Baer (PSU) and K. L. Page (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210610A
94 s after the BAT trigger (Page et al., GCN Circ. 30160). A fading source consistent
with the XRT position (Goad et al. GCN Circ. 30165) and the previously reported
optical counterpart (Hosokawa et al., GCN. Circ. 30161; Xu et al., GCN. Circ. 30162;
Kumar et al., GCN Circ. 30163; Lipunov et al., GCN. 30166; de Wet et al. GCN Circ.
30168; Horiuchi et al., GCN Circ. 30169; Youdong et al., GCN Circ. 30185; Watson et 
al. GCN Circ. 30191) is detected in the initial UVOT exposures. The lack of detection
in the NUV filters for this bright counterpart is consistent with the redshift of 3.5
reported by Zhu et al. (GCN Circ. 30164) and Dutta et al. (GCN Circ. 30200).

The preliminary UVOT position is:
   RA  (J2000) =  13:37:07.59 = 204.28161 (deg.)
   Dec (J2000) = +14:27:55.0  =  14.46527 (deg.)
with an estimated uncertainty of 0.43 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 (fc)          94          244          147      17.09+/-0.03
white              587          892           68      17.92+/-0.07
v                  636          829           38      16.74+/-0.14
v                 4299         4498          196            >18.92
b                  562          754           38      17.69+/-0.12
b                16163        17070          885      20.57+/-0.23
b                23125        45112         1552            >21.16
u                  307          557          245            >20.02
uvw1               685         4908          216            >19.37
uvm2              4503         4703          196            >19.16
uvw2              4094         4294          196            >19.10

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.032 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB210610B
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30247
SUBJECT: GRB 210610B: Swift/UVOT Detection 
DATE:    21/06/17 13:37:18 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <mhs18@psu.edu>

M. H. Siegel (PSU), M. Baer (PSU) and K. L. Page (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210610B
92 s after the BAT trigger (Page et al., GCN Circ. 30170). A fading source consistent
with the XRT position (Osborne et al. GCN Circ. 30189) and the previously reported
optical counterpart (Kumar et al., GCN Circ. 30174; Rumyantsev et al. GCN Circ.
30175; Hu et al., GCN Circ. 30177; de Wet et al., GCN Circ. 30180; Romanov, GCN Circ.
30181; Fynbo et al., GCN Circ. 30182; Moskvitin, GCN Circ. 30187; Fu et al., GCN Circ.
30188) is detected in the initial UVOT exposures.

The preliminary UVOT position is:
   RA  (J2000) =  16:15:40.40 = 243.91833 (deg.)
   Dec (J2000) = +14:23:56.9  =  14.39915 (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 (fc)          92          242          147      13.63+/-1.10
white              584         1355          225      15.24+/-0.02
white           172034       172423          377      20.22+/-0.14
white           286441       292869          328      20.71+/-0.23
white           452008       515231         4066      21.69+/-0.16
v                  634         1405           97      15.63+/-0.05
v                 6631        51903          659      18.26+/-0.09
b                  560         1331           77      15.78+/-0.04
b                81150       133027          865      20.08+/-0.14
u (fc)             304          554          245      13.86+/-0.03
u                  707         1306           58      14.93+/-0.04
u                 4850         5040          186      16.68+/-0.05
u                45786        46567          761      18.06+/-0.05
u               131743       132650          885      20.00+/-0.18
u               365977       418267         3970      21.42+/-0.29
uvw1               683         1282           58      14.51+/-0.06
uvw1              4645         4845          196      16.26+/-0.07
uvw1              7041        45779          989      17.54+/-0.06
uvw1            125974       137480          881      19.53+/-0.20
uvw1            200561       247267         1111      19.95+/-0.24
uvm2              6836         7036          196      16.61+/-0.10
uvw2               783         1034           38      15.05+/-0.09
uvw2             50521        51421          885      18.44+/-0.10

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.044 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB210618A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30248
SUBJECT: GRB 210618A: Fermi GBM Final Real-time Localization
DATE:    21/06/18 01:53:56 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM  <do_not_reply@GIOC.nsstc.nasa.gov>

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

At 01:43:36 UT on 18 Jun 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210618A (trigger 645673421.140258 / 210618072).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 227.8, Dec = 42.5 (J2000 degrees, equivalent to J2000 15h 11m, 42d 30'), with a statistical uncertainty of 7.6 degrees.

The angle from the Fermi LAT boresight is 106.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210618072/quicklook/glg_skymap_all_bn210618072.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210618072/quicklook/glg_healpix_all_bn210618072.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210618072/quicklook/glg_lc_medres34_bn210618072.gif


GRB_name: GRB210618A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30250
SUBJECT: GRB 210618A: Swift detection of a burst
DATE:    21/06/18 02:09:20 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

M. G. Bernardini (INAF-OAB), P. D'Avanzo (INAF-OAB),
H. A. Krimm (NSF), A. Y. Lien (GSFC/UMBC), A. Melandri (INAF-OAB),
K. L. Page (U Leicester), D. M. Palmer (LANL), T. Sbarrato (INAF-OAB)
and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 01:43:37 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 210618A (trigger=1056426).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 235.820, +46.043 which is 
   RA(J2000) = 15h 43m 17s
   Dec(J2000) = +46d 02' 36"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of about 3 sec.  The peak count rate
was ~3600 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 01:44:42.2 UT, 65.3 seconds after
the BAT trigger. No source was detected in the 2.5-s promptly available
image. Due to a short visibility interval, no further data were immediately 
collected. We are waiting for the full dataset to detect and localise the
XRT counterpart. 

Due to the short visibility window, UVOT data are not available at this time. 

Burst Advocate for this burst is M. G. Bernardini (grazia.bernardini AT brera.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: GRB210618A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30251
SUBJECT: GRB 210618A: DDOTI upper limit for the optical afterglow
DATE:    21/06/18 08:37:31 GMT
FROM:    Kin O. C. L. Mendoza at Instituto de Astronoma, UNAM  <koclopez@astro.unam.mx>

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

We observed the field of the GRB 210618A (Fermi GBM Team, GCN circ. 30248
and Bernardini et al., GCN circ. 30250) with the DDOTI wide-field imager at
the Observatorio AstronÃ³mico Nacional on Sierra San Pedro Martir (
http://ddoti.astroscu.unam.mx) from 2021-06-18 03:52:24 UTC to 2021-03-18
06:39:28 UTC (from 2.14 to 4.93 hours after the trigger).

We observed a field of approximately 3.4 degrees in RA and 3.4 degrees in
declination (about 11.55 square degrees), centered on the Swift BAT ground
position of RA 235.74010768 , Dec 46.14225361(J2000), covering  the BAT
error region. We obtained 7604.6 seconds of exposure in the w filter. We
calibrated our images against the APASS catalog.

We find no new sources within the BAT error region. To our 10-sigma limit
we obtain an upper limit of w = 20.47 mag for the optical afterglow.

We thank the staff of the Observatorio AstronÃ³mico Nacional in San Pedro
Martir.


GRB_name: GRB210618A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30252
SUBJECT: GRB 210618A: Swift-XRT observations
DATE:    21/06/18 13:47:22 GMT
FROM:    Maria Grazia Bernardini at INAF/Brera  <grazia.bernardini@brera.inaf.it>

J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore
(U. Leicester), E. Ambrosi  (INAF-IASFPA) , M. Capalbi (INAF-IASFPA),
J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU) and
M. G. Bernardini (INAF-OAB) report on behalf of the Swift-XRT team:

We have analysed 5.2 ks of Photon Counting (PC) mode XRT data for the
Swift-BAT-detected burst GRB 210618A (Bernardini et al. GCN Circ.
30250), collected between T0+65 s and T0+22.6 ks. 

Three uncatalogued X-ray sources have been detected consistent with
being within 296 arcsec of the Swift-BAT position, however none of them
is above the RASS limit or shows definitive signs of fading. Two
sources (Source 1 and Source 4) are consistent within the XRT error
circle with two spectroscopically identified quasars, and the third one
(Source 2) is consistent with a SDSS galaxy with photo_z=0.59 and
marginally consistent with a candidate quasar. Therefore, for the
moment the most plausible afterglow candidate is Source 2. Swift will
perform follow-up observations to confirm this candidate.

Details of these sources are given below:

Source 1:
  RA (J2000):  235.8870  =  15:43:32.87
  Dec (J2000): +46.0253  =  +46:01:31.0
  Error: 8.9 arcsec (radius, 90% conf.)
  Count-rate: (3.82 [+1.19, -1.00])e-3 ct s^-1  
  Distance: 179 arcsec from Swift-BAT position.
  Flux: (1.17 [+0.36, -0.30])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
This source is consistent with SDSS J154332.15+460133.2,
spectroscopically classified as a quasar at z = 0.657. 

Source 2:
  RA (J2000):  235.7698  =  15:43:4.75
  Dec (J2000): +46.0691  =  +46:04:08.6
  Error: 9.3 arcsec (radius, 90% conf.)
  Count-rate: (4.0 +/- 1.0)e-3 ct s^-1  
  Distance: 156 arcsec from Swift-BAT position.
  Flux: (1.35 +/- 0.35)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) 
This source is positionally consistent with SDSS J154305.56+460405.0, a
galaxy with photo_z = 0.590 +/- 0.153 and 12.2 arcsec away from SDSS
J154305.40+460418.7, a candidate quasar (Richards et al., 2015, ApJS,
219, 39).

Source 4:
  RA (J2000):  235.7183  =  15:42:52.39
  Dec (J2000): +46.0336  =  +46:02:01.0
  Error: 8.7 arcsec (radius, 90% conf.)
  Count-rate: (1.48 [+0.78, -0.60])e-3 ct s^-1  
  Distance: 256 arcsec from Swift-BAT position.
  Flux: (7.2 [+3.8, -2.9])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)
This source is positionally consistent with SDSS J154251.96+460206.1,
spectroscopically classified as a quasar at z = 2.130.

Six uncatalogued sources were also detected too far from the GRB
position to be likely afterglow candidates.

The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
https://www.swift.ac.uk/ToO_GRBs/01056426.

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


GRB_name: GRB210618A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30253
SUBJECT: GRB 210618A: Fermi GBM observation
DATE:    21/06/18 16:45:00 GMT
FROM:    Joshua Wood at MSFC/Fermi-GBM  <joshua.r.wood@nasa.gov>

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

"At 01:43:36.14 UT on 18 June 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210618A (trigger 645673421 / 210618072)
which was also detected by the Swift/BAT (M. G. Bernardini et al. 2019, GCN 30250).

The Fermi GBM Final Real-time Localization (GCN 30248) is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 113 degrees.

The GBM light curve consists of multiple peaks
with a duration (T90) of about 3.6 s (50-300 keV).
The time-averaged spectrum from T0-1.6 s to T0+2.2 s is
well fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.62 +/- 0.26 and
the cutoff energy, parameterized as Epeak, is 440 +/- 140 keV

The event fluence (10-1000 keV) in this time interval is
(1.2 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.3 s in the 10-1000 keV band
is 2.1 +/- 0.3 ph/s/cm^2.

A Band function fits the spectrum equally well
with Epeak= 400 +/- 190 keV, alpha = -0.60 +/- 0.32 and beta = -2.3 +/- 0.9.

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

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


GRB_name: GRB210618A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30254
SUBJECT: GRB 210618A: Swift-BAT refined analysis
DATE:    21/06/18 20:58:35 GMT
FROM:    Hans Krimm at NSF/NASA-GSFC  <hkrimm@nsf.gov>

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

Using the data set from T-70 to T+960 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 210618A (trigger #1056426)
(Bernardini, et al., GCN Circ. 30250).  The BAT ground-calculated position is
RA, Dec = 235.763, 46.072 deg which is 
  RA(J2000)  =  15h 43m 03.2s 
  Dec(J2000) = +46d 04' 17.5" 
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.

The mask-weighted light curve shows a fairly complex structure between roughly
T-1.5 and T+0.5 seconds.  The spacecraft slewed away from the burst location
starting at around T+320 seconds. T90 (15-350 keV) is 2.13 +- 0.44 sec (estimated 
error including systematics).

The time-averaged spectrum from T-1.42 to T+0.96 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.18 +- 0.28.  The fluence in the 15-150 keV band is 1.8 +- 0.3 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.50 sec in the 15-150 keV band
is 1.1 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1056426/BA/


GRB_name: GRB210618A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30255
SUBJECT: GRB 210618A: BOOTES-2/TELMA optical upper limit
DATE:    21/06/18 21:24:06 GMT
FROM:    Youdong HU at IAA-CSIC  <huyoudong072@hotmail.com>

Y.-D. Hu, T.-R. Sun, E. Fernandez-Garcia, A. J. Castro-Tirado, M.D. Caballero-Garcia (IAA-CSIC), C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga), R. Fernandez-Munoz (IHSM/UMA-CSIC) and M. Jelinek (ASU-CAS), on behalf of a larger collaboration, report:

The 60cm BOOTES-2/TELMA robotic telescope at IHSM La Mayora (UMA-CSIC) in Algarrobo Costa (Malaga, Spain) automatically responded to the Swift and Fermi trigger of GRB 210618A (Fermi GBM team GCNC 30248, Bernardini et al. GCNC 30250). Images were taken starting at 01:54 UT, but due to poor weather conditions, only images taken after 02:17 UT (~34 min after trigger) could be used. In the co-added 10 x 60 s exposure image (clear filter), no optical afterglow is neither detected within the BAT/Swift error box (Bernardini et al. GCNC 30250) nor associated with the reported XRT/Swift sources (Osborne et al. GCNC 30252) down to 19.6 mag. This non-detection is consistent with the report from Lipunov et al. (GCNC 30249) and Lopez et al. (GCNC 30251).

We thank the staff at La Mayora for its excellent support.


GRB_name: GRB210618A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30256
SUBJECT: GRB 210618A: Swift/UVOT Upper Limits
DATE:    21/06/18 22:41:20 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N. P. M. Kuin (UCL-MSSL) and M. G. Bernardini (INAF-OAB) report
on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210618A
3728 s after the BAT trigger (Bernardini et al., GCN Circ. 30250).
No optical afterglow consistent with the XRT candidates source 1, 2
or 4 (Osborne et al. , GCN Circ. 30252) 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          3728         3878          147         >20.4
white             3728         4496          344         >21.1
v                 4707         4843          133         >19.2
b                 4092         4291          197         >20.5
u                 3886         4086          197         >20.0
w2                4502         4702          197         >20.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.015 in the direction of the burst
(Schlegel et al. 1998).

Since this is a short GRB, further Swift search for late time optical
emission is being planned.


GRB_name: GRB210619A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30257
SUBJECT: GRB 210619A: Fermi GBM Final Real-time Localization
DATE:    21/06/19 12:56:07 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 12:45:43 UT on 19 Jun 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210619A (trigger 645799548.729736 / 210619532).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 73.9, Dec = 12.5 (J2000 degrees, equivalent to J2000 04h 55m, 12d 30'), with a statistical uncertainty of 1.6 degrees.

The angle from the Fermi LAT boresight is 93.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210619532/quicklook/glg_skymap_all_bn210619532.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210619532/quicklook/glg_healpix_all_bn210619532.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210619532/quicklook/glg_lc_medres34_bn210619532.gif


GRB_name: GRB210619A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30258
SUBJECT: GRB 210619A: BALROG localization (Fermi Trigger 645799548 / GRB 210619532)
DATE:    21/06/19 13:06:01 GMT
FROM:    Jochen Greiner at MPE,Garching  <jcg@mpe.mpg.de>

F. Kunzweiler, B. Biltzinger, F. Berlato, J. Burgess & J. Greiner (all MPE Garching) report:

The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
645799548 at 12:45:43 on 19 June 2021 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) = 69.9+/-1.8 deg
Decl.(2000.0) = 8.8+/-1.7 deg
We estimate an additional systematic error of 1 deg.

Further details are available at:
https://grb.mpe.mpg.de/grb/GRB210619532/

The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB210619532/healpix

The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB210619532/json

                        


GRB_name: GRB210619B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30261
SUBJECT: GRB 210619B: Swift detection of a bright burst and optical counterpart
DATE:    21/06/20 00:12:00 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

P. D'Avanzo (INAF-OAB), M. G. Bernardini (INAF-OAB),
A. Y. Lien (GSFC/UMBC), A. Melandri (INAF-OAB),
K. L. Page (U Leicester), D. M. Palmer (LANL) and
T. Sbarrato (INAF-OAB) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 23:59:25 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 210619B (trigger=1056757).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 319.713, +33.860 which is 
   RA(J2000) = 21h 18m 51s
   Dec(J2000) = +33d 51' 35"
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 100 sec.  The peak count rate
was ~100,000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 00:04:53.4 UT, 328.1 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 319.7161, 33.8495 which is equivalent to:
   RA(J2000)  = 21h 18m 51.86s
   Dec(J2000) = +33d 50' 58.2"
with an uncertainty of 11.1 arcseconds (radius, 90% containment). This
location is 38 arcseconds from the BAT onboard position, within the BAT
error circle. No event data are yet available to determine the column
density using X-ray spectroscopy. 

The initial flux in the 2.5 s image was 4.27e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 135 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  = 21:18:52.39 = 319.71831
  DEC(J2000) = +33:51:01.6  =  33.85044
with a 90%-confidence error radius of about 0.61 arc sec. This position is 7.5
arc sec. from the center of the XRT error circle. The estimated magnitude is
14.71 with a 1-sigma error of about  0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.173. 

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: GRB210619B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30263
SUBJECT: GRB 210619B: Ondrejov D50 detection
DATE:    21/06/20 02:47:13 GMT
FROM:    Martin Jelinek at Astro.Inst-AVCR,Ondrejov  <martin.jelinek@asu.cas.cz>

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

We observed the position of the bright GRB 210420B (D'Avanzo et al., GCN
30261) with the D50 telescope of the Astronomical Institute Ondrejov, near
Prague, Czech Republic. We performed a series of unfiltered exposures
starting 23:59:53 UT, between 28 s and 2 h after the trigger.

The optical afterglow (Lipunov et al., GCNC30259 & 30262) is clearly
detected in single images. We can confirm a decaying nature of the object -
the afterglow faded to r'(AB)~17.7 mag during the course of our
observations, which were ended by twillight 2.0h after the trigger. The
alpha decay by the  end of observations was ~0.6, indicating a possible
plateau phase.


GRB_name: GRB210619B
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30264
SUBJECT: GECAM detection of GRB 210619B
DATE:    21/06/20 03:40:05 GMT
FROM:    Zhao Yi at POLAR  <yizhao@ihep.ac.cn>

Y. Zhao, S. L. Xiong, Y. Huang, S. L. Xie, S. Xiao, C. Cai, J. C. Liu,
C. Y. Li, Y. Q. Zhang, W. C. Xue, C. Zheng, Z. W. Guo, X. Y. Zhao,
Z. H. An, C. Chen, G. Chen, W. Chen, M. Gao, K. Gong, D. Y. Guo, J. J. He,
B. Li, C. Li, J. H. Li, Q. X. Li, X. B. Li, X. Q. Li, Y. G. Li, X. H. Liang,
J. Y. Liao, J. C. Liu, X. J. Liu, Y. Q. Liu, F. J. Lu, Q. Luo, X. Ma,
G. Ou, W. X. Peng, R. Qiao, D. L. Shi, J. Y. Shi, L. M. Song,
X. Y. Song, G. X. Sun, X. L. Sun, Y. L. Tuo, C. W. Wang, J. Z. Wang,
P. Wang, X. Y. Wen, Y. B. Xu, Y. P. Xu, S. Yang, M. Yao, Q. B. Yi,
B. X. Zhang, C. Y. Zhang, D. L. Zhang, Fan Zhang, Fei Zhang, H. M. Zhang,
K. Zhang, P. Zhang, S. N. Zhang, Z. Zhang, S. Y. Zhao, S. J. Zheng,
X. Zhou (IHEP), report on behalf of GECAM team:

During the commissioning phase, GECAM-B was triggered in-flight by a long
burst at 2021-06-20T00:00:00.950 UTC (denoted as T0), which was also
observed by Swift/BAT (GCN # 30261) and CALET/GBM (trigNum 1308182178).
Its alert data was promptly downlinked to the ground through the short
message service of BeiDou Navigation Satellite System (BDS). The time
latency of the first BeiDou message relative to the trigger time is about
1 minute.

According to the BDS alert data, this burst mainly consists of multiple
pulses with a duration of more than 60 s. An automatic on-ground
localization was calculated using the light curves and spectrum. Although
the in-flight calibration of energy response and localization has not been
finalized yet, GECAM-B localized this burst to the following position (J2000): 
Ra: 318.7 deg
Dec: 29.2 deg
Err: 7.4 deg (1-sigma, statistical only)
The current systematic error of location is estimated to be several degrees 
which could be minimized by the ongoing calibration.

This GECAM location is consistent with that of Swift/BAT within the error.

The GECAM light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/gecamb_lc_grd_all_combine_77846400.png

The GECAM preliminary location could be found here: 
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/gecamb_skymap_bdm_77846400_V01.png

Please note that all GECAM results here are preliminary. The final analysis
will be published in journal papers or GECAM online catalog.

Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor
(GECAM) mission consists of two small satellites (GECAM-A and GECAM-B) in
Low Earth Orbit (600 km, 29 deg), launched on Dec 10, 2020 (Beijing Time),
which was funded by the Chinese Academy of Sciences (CAS).


GRB_name: GRB210619B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30265
SUBJECT: GRB 210619B: iTelescope T18 detection
DATE:    21/06/20 04:51:29 GMT
FROM:    Albert Kong at NTHU  <akhkong@gmail.com>

A.K.H. Kong (NTHU, Taiwan) reports

We observed the field of GRB 210619B (D'Avanzo et al., GCN 30261) with the
T18 0.32m telescope of iTelescope.Net in Nerpio, Spain. The observation was
done with a V-band filter beginning at 2021-06-20 02:37:43 UT (about 2.6
hours after the trigger) for 180 sec. The optical afterglow (D'Avanzo et
al., GCN 30261) was detected with V=17.9+/-0.2 by calibrating with the
APASS DR10 catalogue.


GRB_name: GRB210619B
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30267
SUBJECT: GRB 210619B: Enhanced Swift-XRT position
DATE:    21/06/20 05:32:43 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.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 1170 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 210619B, 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 = 319.71848, +33.85002 which is equivalent
to:

RA (J2000): 21h 18m 52.44s
Dec (J2000): +33d 51' 00.1"

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: GRB210619B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30268
SUBJECT: GRB 210619B: SARA-KP 0.9m Optical Afterglow Detection
DATE:    21/06/20 08:18:35 GMT
FROM:    Kyle Pellegrin at Clemson University  <pelleg2@g.clemson.edu>

K. Pellegrin, S. Anandagoda, and D. Hartmann report:

We observed the field of GRB 210619B detected by Swift BAT (Dâ€™Avanzo et al.,
GCN #30261), Global MASTER-Net (Lipunov et al., GCN #30262), GECAM (Zhao et
al., GCN #30264), iTelescope (Kong, GCN #30265), and Ondrejov D50 (M.
Jelinek et al., GCN #30263) using the SARA 0.9m optical telescope located
at Kitt Peak, AZ, USA, equipped with the Alta-E6-1105 camera.

Observation started at 05:19:14 UTC on 2021-06-20 and ended at 06:13:23 UTC
on 2021-06-20. We obtained a series of 60s exposure frames in the
Johnson-Cousins R filter. We detect the optical afterglow of GRB 210619B at
the enhanced Swift-XRT position (Beardmore, et al., GCN #30267).

The estimated magnitude of the GRB afterglow was found by stacking 20
images of 60s each in the Johnson-Cousins R band filter. The GRB was
visible in each of the stacked images.

T_start-T0 (hrs)   T_end-T0 (hrs)     Start Date (UTC) Filter Magnitude
(mag)

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

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

5.32 5.70          2021-06-20T05:19:14        R      18.51

5.73 6.22   2021-06-20T05:43:59   R             18.77


Photometry is done based on the PanSTARRS catalog.

The Southeastern Association for Research in Astronomy (SARA) consortium
operates three telescopes: the 0.9-m SARA-KP at Kitt Peak in Arizona, and
the 0.6-m SARA-CT at Cerro Tololo in Chile, and the 1.0-m SARA-RM (formerly
the JKT) telescope at Roque de los Muchachos Observatory in the Canary
Islands. For more information see: Keel et al. (2016):
https://iopscience.iop.org/article/10.1088/1538-3873/129/971/015002

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


GRB_name: GRB210619B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30269
SUBJECT: GRB 210619B: Swift-XRT refined Analysis
DATE:    21/06/20 09:37:58 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), E. Ambrosi 
(INAF-IASFPA) , M. Capalbi (INAF-IASFPA), M. Perri (SSDC & INAF-OAR),
A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), D.N. Burrows (PSU),
P.A. Evans (U. Leicester) and P. D'Avanzo report on behalf of the
Swift-XRT team:

We have analysed 6.7 ks of XRT data for GRB 210619B (D'Avanzo et al.
GCN Circ. 30261), from 208 s to 24.8 ks after the  BAT trigger. The
data comprise 1.5 ks in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Beardmore et al. (GCN Circ. 30267).

The light curve can be modelled with an initial power-law decay with an
index of alpha=0.938 (+/-0.014), followed by a break at T+5780 s to an
alpha of 1.23 (+/-0.07).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.886 (+/-0.019). The
best-fitting absorption column is  2.68 (+/-0.08) x 10^21 cm^-2, in
excess of the Galactic value of 2.0 x 10^21 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.88 (+/-0.08) and a
best-fitting absorption column of 2.6 (+/-0.3) x 10^21 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 4.0 x 10^-11 (5.4 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      2.6 (+/-0.3) x 10^21 cm^-2
Galactic foreground: 2.0 x 10^21 cm^-2
Excess significance: 2.8 sigma
Photon index:      1.88 (+/-0.08)

If the light curve continues to decay with a power-law decay index of
1.23, the count rate at T+24 hours will be 0.24 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 9.4 x
10^-12 (1.3 x 10^-11) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01056757.

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


GRB_name: GRB210619B
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30270
SUBJECT: GRB 210619B: Fermi-LAT detection
DATE:    21/06/20 10:23:35 GMT
FROM:    Roberta Pillera at Politecnico and INFN Bari  <roberta.pillera@ba.infn.it>

M. Axelsson (KTH & Stockholm Univ.), R. Pillera (Politecnico and INFN 
Bari) and
F. Longo (University and INFN Trieste.) report on behalf of the 
Fermi-LAT Collaboration:

Fermi-LAT has detected high-energy emission from GRB 210619B, which was 
also detected
by Swift (GCN 30261), Global MASTER-net (GCN 30262), Ondrejov D50 (GCN 
26263),
GECAM (GCN 26264), iTelescope T18 (GCN 30265) and SARA-KP (GCN 30268).

The best LAT on-ground location is found to be

(RA, Dec) = 319.7, 33.9 (degrees, J2000)

with an error radius of 0.13 deg (90% containment, statistical error 
only). This position
is consistent with the XRT localization (GCN 30267). The location of the 
GRB was outside
the LAT FoV at the time of the trigger (T0 = 23:59:25 UT on 2021-06-19) 
and came into
view at T0+200 s.

The data from the Fermi-LAT show a significant increase  in the event 
rate that is spatially
correlated with the Swift emission with high significance. The highest 
energy photon is a
8.3 GeV event detected ~410 s after the trigger.

The photon flux above 100 MeV in the time interval 200-1000 s after the 
Swift trigger is
(1.6 +/- 1.2) e-06 ph/cm2/s.

The estimated photon index above 100 MeV is -1.5 +/- 0.3.

The Fermi-LAT point of contact for this burst is
Roberta Pillera (roberta.pillera@ba.infn.it).

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


GRB_name: GRB210619B
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30271
SUBJECT: GRB 210619B: Liverpool telescope imaging of a red afterglow
DATE:    21/06/20 11:14:52 GMT
FROM:    Daniel Perley at Liverpool JMU  <d.a.perley@ljmu.ac.uk>

D. A. Perley (LJMU) reports:

We acquired multicolor imaging of the optical afterglow of GRB 210619B 
(D'Avanzo et al., GCN 30261) using the IO:O camera of the 2m robotic 
Liverpool Telescope.  The afterglow was observed twice in the ugriz 
filters on 2021-06-20 UT, with the first epoch taking place between 
02:35:06 and 02:42:40 and the second between 03:49:15 and 03:56:49.

Photometry with reference to Pan-STARRS 1 secondary standard stars in 
the field gives the following magnitudes:

t-tburst(d) filter mag    unc
0.10772     g      18.58  0.03
0.10879     r      17.82  0.03
0.10984     i      17.44  0.04
0.11227     z      17.17  0.04
0.15920     g      18.93  0.03
0.16028     r      18.11  0.03
0.16133     i      17.74  0.04
0.16376     z      17.47  0.04

These values have not been corrected for Galactic extintion.

The colors (after applying a Galactic extinction correction) suggest a 
moderately dust-reddened afterglow.









DisclaimerNone


GRB_name: GRB210619B
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30272
SUBJECT: GRB 210619B: Redshift from OSIRIS/GTC
DATE:    21/06/20 11:28:59 GMT
FROM:    Antonio de Ugarte Postigo at IAA-CSIC  <deugarte@iaa.es>

A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), D. A. Kann, C. Thoene, M. Blazek, J.F. Agui Fernandez, (all HETH/IAA-CSIC), L. Izzo (DARK/NBI), N.R. Tanvir (U. Leicester), J.P.U. Fynbo (DAWN/NBI), A. M. Garcia Rodriguez, and G. Gomez (GTC) report:

We observed the afterglow of GRB 210619B (Dâ€™Avanzo et al. GCN 30261; Lipunov et al. GCN 30262; Jelinek et al. GCN 30263; Zhao et al. GCN 30264; Kong GCN 30265; Beardmore et al. GCN 30267; Pellegrin et al. GCN 30268; Axelsson et al., GCN 30270; Perley GCN 30271) with OSIRIS on the 10.4 m GTC telescope at Roque de los Muchachos Observatory, in the Island of La Palma. The observation started at 2:27 UT (2.45 hr after the burst) and consisted of 3x600 s with grism R1000B, covering the spectral range between 3700 and 7800 AA.

In a preliminary reduction with old calibrations we detect a strong continuum with a plethora of absorption features superposed to it. We identify features that include SiII, SiIV, OI, CI, CII, CIV, FeII, AlII, AlIII, NiII, CrII ZnII, as well as fine structure lines of SiII, FeII, NiII at a common redshift of 1.937, which we identify as the redshift of the GRB. We also detect an intervening system with MgII and MgI at z=1.095.

Additionally, the flux calibrated spectrum shows a strong broad absorption feature at ~4500AA, resembling a dust bump. This could be consistent with a 2175 AA dust feature due to the intervening absorber.

We note that at a redshift of 1.937, the initial prompt emission spike is extremely luminous, and we expect the afterglow to be among the most luminous prompt flashes ever detected. Using the fluence reported on the automatic Swift/BAT analysis page in the 15-350 keV band, we derive an E_iso ~ 1.7e54 erg, without any k-correction.  This implies GRB 210619B will likely be among the most energetic GRBs ever detected once a k-correction to the bolometric band is applied.

Further analysis is ongoing. We encourage further observations.


GRB_name: GRB210619B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30273
SUBJECT: GRB 210619B: KAIT Optical Detection
DATE:    21/06/20 13:48:29 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 the Swift GRB 210619B (D'Avanzo et al.,

GCN 30261) starting at ~8.05 hours after the Swift trigger.

A total of 60x60s images were obtained in the clear (roughly R)

filter. The optical afterglow (D'Avanzo et al., GCN 30261; Lipunov et al.,

GCN 30262; Jelinek et al., GCN 30263; Kong, GCN 30265; Pellegrin et al.,

GCN 30268; Perley, GCN 30271) was clearly detected in each single image.

We measured its brightness of 18.5 +/- 0.1 mag at 8.05 hours after burst,

and decayed to be 18.8 +/- 0.1 mag at 11.07 hours after burst, calibrated

to the Pan-STARRS1 catalog.


GRB_name: GRB210619B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30274
SUBJECT: GRB 210619B: Liverpool Telescope r'-band observations
DATE:    21/06/20 15:37:41 GMT
FROM:    Martin Blazek at HETH/IAA-CSIC  <alf@iaa.es>

M. Blazek, D. A. Kann (both HETH/IAA-CSIC), A. de Ugarte-Postigo (HETH/IAA-CSIC,
DARK/NBI), C. Thoene and J.F. Agui Fernandez (both HETH/IAA-CSIC) report:

We observed the afterglow of GRB 210619B (Swift detection: D'Avanzo et al., GCN
30261; GECAM detection: Zhao et al., GCN 30264; Fermi-LAT detection: Axelsson et
al., GCN 30270; Afterglow detections: Lipunov et al., GCN 30259; D'Avanzo et
al., GCN 30261; Lipunov et al., GCN 30262; Jelinek et al., GCN 30263; Kong, GCN
30265; Pellegrin et al., GCN 30268; Perley, GCN 30271; Zheng & Filippenko, GCN
30273; Redshift: de Ugarte Postigo, GCN 30272) with the 2-m Liverpool Telescope
located in La Palma, Spain using IO:O camera. The observation started at
02:57:49 UT on June 20, 2021 (t-t0 = 2.97 hours). We obtained 60x45 seconds
exposures in r'. The afterglow is clearly detected in each image. Comparing
to 33 check stars from the PanSTARRS catalogue we derived the decay starting with

r' = 17.91 +- 0.01 mag

and ending at 03:45:43 UT (t-t0 = 3.77) hours with

r' = 18.10 +- 0.02 mag

Magnitudes are given in AB photometric system. These values have not been
corrected for Galactic extintion.


GRB_name: GRB210619B
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30275
SUBJECT: GRB 210619B: CAHA 2.2m photometric monitoring
DATE:    21/06/20 15:53:18 GMT
FROM:    Alexander Kann at IAA-CSIC  <kann@iaa.es>

D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC, 
DARK/NBI), M. Blazek, C. Thoene, J.F. Agui Fernandez, Ginger (all 
HETH/IAA-CSIC), and J. I. Vico Linares (CAHA) report:

We observed the afterglow of GRB 210619B (Swift detection: D'Avanzo et 
al., GCN 30261; GECAM detection: Zhao et al., GCN 30264; Fermi-LAT 
detection: Axelsson et al., GCN 30270; Afterglow detections: Lipunov et 
al., GCN 30259; D'Avanzo et al., GCN 30261; Lipunov et al., GCN 30262; 
Jelinek et al., GCN 30263; Kong, GCN 30265; Pellegrin et al., GCN 30268; 
Perley, GCN 30271; Zheng & Filippenko, GCN 30273; Blazek et al., GCN 
30274; Redshift: de Ugarte Postigo, GCN 30272) with CAFOS mounted at the 
2.2m Calar Alto telescope (Almeria, Spain). After a weather-induced 
delay, we obtained 80 x 60 s images in Ic. The afterglow is clearly 
detected in each image.

The sequence starts at 01:23 UT and ends at 03:43 UT on 2021-06-20 
(0.05836 to 0.15479 d after burst trigger). Comparing to a single star 
with a magnitude derived from PanSTARRS and transformed following Lupton 
(2005), we find the afterglow decays from Ic (AB) = 16.75 +/- 0.05 mag 
to Ic (AB) = 17.45 +/- 0.05 mag.

Further observations are planned.


GRB_name: GRB210619B
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30276
SUBJECT: Konus-Wind detection of GRB 210619B
DATE:    21/06/20 15:56:25 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

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

The very bright, long-duration GRB 210619B
(Swift-BAT detection: D'Avanzo et al., GCN Circ. 30261;
GECAM detection: Zhao et al., GCN Circ. 30264;
Fermi-LAT detection: Axelsson et al., GCN Circ. 30270)
triggered Konus-Wind at T0=86368.157 s UT (23:59:28.157).

The burst light curve shows a bright hard initial episode,
which starts at ~T0 and has a duration of ~10 s,
followed by weaker pulses. The total burst duration is ~80 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/GRB210619_T86368/

As observed by Konus-Wind, the burst
had a fluence of 4.60(-0.13,+0.13)x10^-4 erg/cm2,
and a 64-ms peak flux, measured from T0+0.640 s,
of 1.54(-0.12,+0.12)x10^-4 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+66.816 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -1.02(-0.03,+0.04),
the high energy photon index beta = -2.10(-0.04,+0.03),
the peak energy Ep = 261(-13,+14) keV
(chi2 = 118/96 dof).

The spectrum near the maximum count rate
(measured from T0+0.512 to T0+0.768 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.41(-0.11,+0.12),
the high energy photon index beta = -2.06(-0.12,+0.09),
the peak energy Ep = 572(-81,+98) keV
(chi2 = 76/60 dof).

Assuming the redshift z=1.937
(de Ugarte Postigo et al., GCN Circ. 30272)
and a standard cosmology model with H_0 = 67.3 km/s/Mpc,
Omega_M = 0.315, and Omega_Lambda = 0.685 (Planck Collaboration, 2014),
we estimate the following rest-frame parameters:
the isotropic energy release E_iso is 4.41(-0.12,+0.12)x10^54 erg,
the peak luminosity L_iso is 4.34(-0.34,+0.34)x10^54 erg/s,
the rest-frame peak energy of the time-integrated spectrum,
Ep,i,z, is 767(-38,+41) keV, and the rest-frame peak energy of
the 'peak' spectrum, Ep,p,z, is 1680(-238,+288) keV.
With these energetics, the burst lies within the 90% prediction bands
for both 'Amati' and 'Yonetoku' relations built for the sample
of 138 long KW GRBs with known redshifts
(Tsvetkova et al., ApJ 850 161, 2017),
see http://www.ioffe.ru/LEA/GRBs/GRB210619_T86368/GRB210619B_rest_frame.pdf.

Among the KW GRB sample, GRB 210619B is within top 4% in the terms
of E_iso and have L_iso comparable to the most luminous GRB 110918A 
(Frederiks et al., ApJ 779, 151, 2013).

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


GRB_name: GRB210619B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30277
SUBJECT: GRB 210619B: Xinglong TNT optical observations
DATE:    21/06/20 16:13:35 GMT
FROM:    Liping Xin at NAOC, SVOM  <xlp@nao.cas.cn>

L. P. Xin (NAOC), X. Li (THU),  Y. L. Qiu(NAOC), J. Y. Wei(NAOC),  
J. Wang(GXU),  L. H. Li (NAOC),  C. Wu(NAOC),  E. W. Liang(GXU), 
X. H. Han (NAOC), A. Y. Zhou (NAOC) and J. S. Deng(NAOC) report:

We began to observe GRB 210619B (Swift detection: D'Avanzo et al., GCN
30261; GECAM detection: Zhao et al., GCN 30264; Fermi-LAT detection: 
Axelsson et al., GCN 30270; Konus-Wind detection: Svinkin et al., GCN 30276; 
Afterglow detections: Lipunov et al., GCN 30259; D'Avanzo et
al., GCN 30261; Lipunov et al., GCN 30262; Jelinek et al., GCN 30263; 
Kong, GCN 30265; Pellegrin et al., GCN 30268; Perley, GCN 30271; 
Zheng &amp; Filippenko, GCN 30273; Redshift: de Ugarte Postigo, GCN 30272, 
Blazek et al., GCN 30274; Kann et al., 30275) with Xinglong TNT telescope, 
China, at 15:23:44 (UT), 20th. June. 2021,  about 14.43 hours after the burst, 

A series of  R and B band images were obtained. 
The afterglow is clear detected in our single image with a magnitude of 19.0 mag 
in R band comparing to several nearby USNO B1.0 stars.

Observations are still continuing. 

We acknowledge the excellent support from Xinglong staff YuGuang Sun. 

The message may be cited.


GRB_name: GRB210619B
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30278
SUBJECT: GRB 210619B: Swift/UVOT Detection
DATE:    21/06/20 16:42:40 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 210619B
136 s after the BAT trigger (D'Avanzo et al., GCN Circ. 30261).
A source consistent with the XRT position (Beardmore et al., GCN Circ.
30267)
was detected in the initial UVOT exposures consistent with the reported
afterglow by Lipunov et al. (GCN Circ. 30259), Jelinek et al. (GCN Circ.
30263),
Kong (GCN Circ. 30265), Kellegrin et al. (GCN Circ. 30268), and Zheng &
Filippenko (GCN Circ. 30273). A redshift measurement of z=1.937 was
reported
by de Ugarte Postigo et al. (GCN Circ. 20272) which puts the Lyman break
right at the center of the UVOT uvm2 filter.

The preliminary UVOT position is:
    RA  (J2000) =  21:18:52.38 = 319.71825 (deg.)
    Dec (J2000) = +33:51:01.6  =  33.85044 (deg.)
with an estimated uncertainty of 0.42 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              136          285          147         14.67 +/- 0.02
white              794          814           19         16.66 +/- 0.06
v                  679          699           19         15.59 +/- 0.10
b                  604          624           20         16.39 +/- 0.08
u                  348          598          246         15.60 +/- 0.03
w1                 729         1107           39         17.22 +/- 0.19
m2                 704         1776          117        >19.3
w2                 655         1726          136         19.20 +/- 0.31

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.173 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB210619B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30279
SUBJECT: GRB 210619B: Fermi GBM detection
DATE:    21/06/20 18:40:56 GMT
FROM:    Suraj Poolakkil at UAH  <sp0076@uah.edu>

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

"At 23:59:25.60 UT on 19 June 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210619B (trigger 645839970 / 210619999)
which was also detected by the Swift/BAT (D'Avanzo et al. 2021, GCN 30261),
Fermi-LAT (Axelsson et al. 2021, GCN 30270) and Konus-Wind (Svinkin et
al. 2021, GCN 30276).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 109 degrees.

The GBM light curve consists of a single peak followed by some
extended emission with a duration (T90) of about 55 s (50-300 keV).
The time-averaged spectrum from T0 s to T0+61.4 s
is best fit by a Band function, with Epeak = 210 +/- 3 keV,
alpha = -0.86 +/- 0.01 and beta = -1.99 +/- 0.01.

The event fluence (10-1000 keV) in this time interval is
(307.93 +/- 0.9830)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.51 s in the 10-1000 keV band
is 238.6 +/- 1.3 ph/s/cm^2.

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

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


GRB_name: GRB210619B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30280
SUBJECT: GRB 210619B: Liverpool Telescope First Hour Observations
DATE:    21/06/20 19:09:26 GMT
FROM:    Manisha Shrestha at Liverpool John Moores U  <m.shrestha@ljmu.ac.uk>

M. Shrestha (Liverpool JMU),  A. Gomboc (Univ. Nova Gorica), C. Guidorzi (Univ. Ferrara) ,  S. Kobayashi (LJMU), A. Melandri (INAF), C. Mundell (Univ. Bath), R. Smith (LJMU) , I.A. Steele (LJMU), report on behalf of a wider collaboration:



We observed the field of Swift GRB 210619B (D'Avanzo et al. GCN 30261; Jelinek et al. GCN 30263; Lipunov et al. GCN 30259; Zhao et al. GCN 30261; Kong et al. GCN 30265; Axelsson et al. GCN 30270; de Ugarte Postigo et al. GCN 30272; Zheng et al. GCN 30273; Blazek et al. GCN 30274; Kann et al. GCN 30275; Svinkin et al. GCN 30276; Xin et al. GCN 30277; Perley et al. GCN 30271 ) with the 2.0m Liverpool Telescope (LT), La Palma on 2021 June 20 starting at 00:21:14.141 UT for a period of 2 hours using the MOPTOP optical imaging polarimeter in the r band.  Data was calibrated with respect to nearby APASS secondary standard stars.



We confirm the optical counterpart reported by Swift UVOT (GCN 30261).



At T=1318 seconds after the BAT trigger time, we measure r = 16.1 mag.  Detailed analysis is ongoing.







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GRB_name: GRB210619B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30281
SUBJECT: GRB 210619B: steepening of the decay observed at the D50
DATE:    21/06/21 00:55:28 GMT
FROM:    Martin Jelinek at Astro.Inst-AVCR,Ondrejov  <martin.jelinek@asu.cas.cz>

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

We observed the optical afterglow of GRB 210619B (D'Avanzo et al. GCN
30261; Jelinek et al. GCN 30263; Lipunov et al. GCN 30259; Zhao et al. GCN
30261; Kong et al. GCN 30265; Axelsson et al. GCN 30270; de Ugarte Postigo
et al. GCN 30272; Zheng et al. GCN 30273; Blazek et al. GCN 30274; Kann et
al. GCN 30275; Svinkin et al. GCN 30276; Xin et al. GCN 30277; Perley et
al. GCN 30271, Shrestha et al. GCN 30280) with the D50 in Ondrejov through
difficult conditions with some passing clouds.

On a combined (86x60s, Sloan r') image with the mean exposure time 0.98
days post burst we measure r'(AB) = 20.2 +- 0.2. This is significantly
below any extrapolation of photometric points published before, and
suggests a break and a steepening of the decay.


GRB_name: GRB210619B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30282
SUBJECT: GRB 210619B: Swift-BAT refined analysis
DATE:    21/06/21 02:26:59 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC),
P. D'Avanzo (INAF-OAB), H. A. Krimm (NSF),
S. Laha (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU),
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(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 210619B (trigger #1056757)
(D'Avanzo et al., GCN Circ. 30261).  The BAT ground-calculated position is
RA, Dec = 319.718, 33.850 deg which is
   RA(J2000)  =  21h 18m 52.3s
   Dec(J2000) = +33d 50' 58.6"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 36%.

The mask-weighted light curve shows a bright pulse that starts at ~T0
and peaks at ~T+1 s, and is followed by several overlapping pulses that
last till ~T+105 s. T90 (15-350 keV) is 60.90 +- 0.28 sec (estimated
error including systematics).

The time-averaged spectrum from T-0.25 to T+105.38 sec is best fit
by a simple power-law model.  The power law index of the time-averaged
spectrum is 1.41 +- 0.02.  The fluence in the 15-150 keV band is
9.5 +- 0.1 x 10^-5 erg/cm2. The 1-sec peak photon flux measured from
T+0.95 sec in the 15-150 keV band is 115.0 +- 2.2 ph/cm2/sec.
All the quoted errors are at the 90% confidence level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1056757/BA/


GRB_name: GRB210619B
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30283
SUBJECT: GRB 210619B: SRG/ART-XC detection
DATE:    21/06/21 06:37:17 GMT
FROM:    Sergey Molkov at Space Research Inst., Moscow  <molkov@iki.rssi.ru>

V. Levin, S. Molkov, I. Mereminskiy, Ð. Lutovinov, A. Semena
and E. Filippova (IKI RAN)
report on behalf of SRG/ART-XC team:


At 23:59:21 UT on 19/06/2021 the Mikhail Pavlinsky ART-XC telescope on 
board the Spektr-RG observatory
detected a short peak in the 40-120 keV count rate. This peak is 
associated with the luminous GRB210619B
registered simultaneously by other space-bourne missions (Swift/BAT 
(D'Avanzo et al. 2021, GCN 30261),
GECAM (Zhao et al. 2021, GCN 30264), Fermi-LAT (Axelsson et al. 2021, 
GCN 30270), Konus-Wind
(Svinkin et al. 2021, GCN 30276), Fermi/GBM (Poolakkil and Meegan 2021, 
GCN  30279)).

The burst light curve is similar to what observed by other telescopes, 
with a prominent initial peak
(that lasted for 6 s and having a typical fast rise exponential decay 
form) and several
consecutive peaks, roughly coincident with ones detected by Konus-Wind.

The angle between telescope axis and the burst was 45 degrees, which 
means that the burst emission
had penetrated through the side shield of ART-XC detectors. This 
significantly complicates the spectral analysis,
which will be presented elsewhere.

The Mikhail Pavlisky ART-XC is an X-ray telescope working in the  hard 
X-ray band (above 4 keV) in the
Langrangian point L2. It could observe brightest GRBs through its 
side/back shielding, providing an
additional leverage for the  IPN-like triangulation of such events.


GRB_name: GRB210619B
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30284
SUBJECT: GRB 210619B: CALET Gamma-Ray Burst Monitor detection
DATE:    21/06/21 10:39:15 GMT
FROM:    Valentin Pal'shin at AGU  <val@phys.aoyama.ac.jp>

Y. Kawakubo (LSU),
A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU),
K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), Y. Asaoka (ICRR),
S. Torii, Y. Akaike, K. Kobayashi (Waseda U),
Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC),
M. L. Cherry (LSU), S. Ricciarini (U of Florence),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

The long bright GRB 210619B (Swift detection: D'Avanzo et al.,
GCN Circ. 30261, Lien et al., GCN Circ. 30282; GECAM detection: Zhao et al.,
GCN Circ. 30264; Fermi-LAT detection: Axelsson et al., GCN Circ. 30270;
Konus-Wind detection: Svinkin et al., GCN Circ. 30276;
Fermi GBM detection: Poolakkil and Meegan, GCN Circ. 30279;
SRG/ART-XC detection: Levin et al., GCN Circ. 30283;
https://gcn.gsfc.nasa.gov/other/210619B.gcn3) triggered the CALET Gamma-ray
Burst Monitor (CGBM) at 23:59:21.940 UTC on 19 June 2021
(http://cgbm.calet.jp/cgbm_trigger/flight/1308182178/index.html).
The burst signal was seen by all CGBM detectors.

The burst light curve shows the bright initial pulse which starts
at T+3.5 sec and peaks at T+4.3 sec, followed by several weaker pulses
which end at T+85.4 sec. The T90 and T50 durations measured by the SGM data
are 49.9 +- 1.8 sec and 14.4 +- 0.6 sec (40-1000 keV), respectively.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1308182178/

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


GRB_name: GRB210621A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30285
SUBJECT: GRB 210621A: Fermi GBM Final Real-time Localization
DATE:    21/06/21 10:54:22 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 10:44:03 UT on 21 Jun 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210621A (trigger 645965048.749786 / 210621447).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 248.3, Dec = -61.1 (J2000 degrees, equivalent to J2000 16h 33m, -61d 06'), with a statistical uncertainty of 8.6 degrees.

The angle from the Fermi LAT boresight is 78.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210621447/quicklook/glg_skymap_all_bn210621447.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210621447/quicklook/glg_healpix_all_bn210621447.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210621447/quicklook/glg_lc_medres34_bn210621447.gif


GRB_name: GRB210619B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30286
SUBJECT: GRB 210619B: GIT optical follow-up and confirmation of jet-break
DATE:    21/06/21 11:36:42 GMT
FROM:    Harsh Kumar at Indian Inst of Tech,Bombay  <harshkosli13@gmail.com>

H. Kumar(IITB), U. Stanzin (IAO), V. Bhalerao(IITB), G. C. Anupama(IIA), S.
Barway(IIA) report on behalf of the GIT team:

We observed GRB 210619B detected by Swift-BAT (D'Avanzo et al. GCN #30261)
also see(Lipunov et al. GCN #30259; Zhao et al. GCN #30261; Jelinek et al.
GCN #30263; Kong et al. GCN #30265; Axelsson et al. GCN #30270; Perley et
al. GCN #30271; de Ugarte Postigo et al. GCN #30272; Zheng et al. GCN
#30273; Blazek et al. GCN #30274; Kann et al. GCN #30275; Svinkin et al.
GCN #30276; Xin et al. GCN #30277; Shrestha et al. GCN #30280; Jelinek et
al. GCN #30281), with 0.7m GROWTH-India Telescope (GIT). We obtained multiple
300-sec exposures in the g', r' and i' filters starting at
2021-06-20T18:04:27 UT. We clearly detected the afterglow in our stacked images
at R.A.(J2000)= 21:18:52.39, DEC.(J2000)= +33:51:01.10. The photometric
results follow as:

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

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

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

2459386.26006 | 18.25 | g' | 21.133 +/- 0.07 |

2459386.27823 | 18.69 | r' | 20.184 +/- 0.05 |

2459386.29675 | 19.14 | i' | 20.091 +/- 0.06 |

2459386.33501 | 20.05 | g' | 21.142 +/- 0.07 |

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

Our r' magnitude is significantly fainter as compared to the extrapolation
of power-law from previous observations. We thus confirm jet-break in GRB
210619B, first suggested by Jelinek et al. GCN #30281. The magnitudes are
calibrated against PanSTARRS (Flewelling et al., 2018) and not corrected
for Galactic extinction.

The GROWTH India Telescope (GIT) is a 70-cm telescope with a 0.7-degree
field of view, set up by the Indian Institute of Astrophysics and the
Indian Institute of Technology Bombay with support from the Indo-US Science
and Technology Forum (IUSSTF) and the Science and Engineering Research
Board (SERB) of the Department of Science and Technology (DST), Government
of India (https://sites.google.com/view/growthindia/). It is located at the
Indian Astronomical Observatory (Hanle), operated by the Indian Institute
of Astrophysics (IIA).


GRB_name: GRB210621A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30287
SUBJECT: Fermi GRB 210621A: Global MASTER-Net observations report 
DATE:    21/06/21 12:51:43 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

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

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

D. Buckley 
(South African Astronomical Observatory),

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

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

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




MASTER-OAFA robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 210621A ( Fermi GBM team, GCN 30285) errorbox  353 sec after notice time and 399 sec after trigger time at 2021-06-21 10:50:43 UT, with upper limit up to  15.2 mag. Observations started at twilight.  The observations began at zenith distance = 75 deg. The sun  altitude  is -9.0 deg. 

The galactic latitude b = -9 deg., longitude l = 327 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1641646

We obtain a following upper limits.  

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

     430 | 2021-06-21 10:50:43 |         MASTER-OAFA | (16h 35m 08.88s , -58d 53m 13.5s) |   C |    60 | 15.2 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB210619B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30288
SUBJECT: GRB 210619B: REM optical/NIR afterglow detection
DATE:    21/06/21 13:00:05 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <pda.davanzo@gmail.com>

P. D'Avanzo, A. Melandri, S. Covino, D. Fugazza, (INAF-OAB) on behalf of the REM team, report:

We observed the field of GRB 210619B (D'Avanzo et al., GCN Circ. 30261) with the REM 60cm robotic telescope 
located at the ESO premise of La Silla (Chile). The observations were carried in the g, r, i, z, J, H and K bands, starting 
on 2021 June 20 at 06:07:59 UT (i.e. 6.14 hours after the burst) and lasting for about one hour. 

The optical/NIR afterglow (D'Avanzo et al., GCN Circ. 30261) is detected in all bands. From preliminary photometry we 
derive the following magnitudes: 

r = 18.52 +/-  0.12
(AB; calibrated against the Pan-STARRS catalogue)

J = 17.10  +/- 0.24 
H = 16.61  +/- 0.25 
K = 15.13  +/- 0.23 
(Vega; calibrated against the 2MASS catalogue)

at a mid time of t-t0 = 6.3 hours.


GRB_name: GRB210619B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30289
SUBJECT: GRB 210619B: TNG NIR observations of the afterglow
DATE:    21/06/21 13:02:39 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <pda.davanzo@gmail.com>

P. D'Avanzo (INAF-OAB), V. D'Elia (ASI-SSDC), A. Melandri, G. Tagliaferri (INAF-OAB), A. Rossi (INAF-OAS), 
L. Di Fabrizio, D. Carosati (INAF-TNG) on behalf of the CIBO collaboration report:

We observed the NIR afterglow of GRB 210619B (D'Avanzo et al., GCN Circ. 30261) with the Italian 3.6m TNG 
telescope equipped with the near-infrared camera NICS. A series of images were obtained with the J and K filters 
on 2021-06-21 from 01:27:06 UT to 02:49:36 UT (i.e. at a mid time of about 1.09 days after the burst). 

With preliminary photometry we derive the following magnitudes:

J = 17.90  +/- 0.05 
K = 16.43  +/- 0.11 
(Vega; calibrated against the 2MASS catalogue).


GRB_name: GRB210619B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30290
SUBJECT: GRB 210619B: SEDM Optical Observations
DATE:    21/06/21 13:23:39 GMT
FROM:    Virginia Cunningham at U of MD  <vcunning@umd.edu>

V. Cunningham (U of Maryland), J. D. Neill (Caltech), S. B. Cenko
(NASA GSFC), and R. Walters (Caltech) report on behalf of the SEDM
team:

We observed the optical counterpart to GRB 210619B (D'Avanzo et al.,
GCN 30261) with the Spectral Energy Distribution Machine (SEDM) on
the 60 inch telescope at Palomar Observatory. The SEDM is a low
resolution (R ~ 100) integral field unit spectrometer with a multi-band
(ugri) rainbow camera imager (see Blagorodnova et al. 2018, PASP,
130, 035003, and Rigault et al. 2019, A&A, 627, A115). The SEDM
began observing the optical counterpart at 06:37:52 UTC (6.5 hours
after the burst trigger time). We performed a 2880 s exposure over the
wavelength range 3800-9200 A.

The continuum emission is well-fit by a power law spectrum with index
alpha = 2.8 (f_nu ~ nu^-alpha). The noise level of the spectrum,
especially at wavelengths bluer than 5000 A, make it difficult to confirm
the redshift reported by OSIRIS/GTC (GCN 30272).

[GCN OPS NOTE(22jun21):  Per author's request, the error in the sentence:
"The SEDM began observing the optical counterpart at 00:01:33 UTC
(1.5 hours after the burst trigger time)" and should be replaced with:
"The SEDM began observing the optical counterpart at 06:37:52 UTC
(6.5 hours after the burst trigger time)".]


GRB_name: GRB210619B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30291
SUBJECT: GRB 210619B: SAO RAS optical observations
DATE:    21/06/21 13:32:22 GMT
FROM:    Moskvitin Alexander at SAO RAS  <mosk@sao.ru>

A. S. Moskvitin and O. A. Maslennikova (SAO RAS),
report on behalf of the GRB follow-up team.

We observed the field of Swift GRB 210619B (D'Avanzo et al.,
GCNs #30261, #30288, #30289; Jelinek et al., GCNs #30263, #30281;
Lipunov et al., GCN #30259; Zhao et al., GCN #30261; Kong et al.,
GCN #30265; Axelsson et al., #GCN 30270; de Ugarte Postigo et al.,
GCN #30272; Zheng et al., GCN #30273; Blazek et al., GCN #30274;
Kann et al., GCN #30275; Svinkin et al., GCN #30276; Xin et al.,
GCN $30277; Perley et al., GCN #30271, Shrestha et al., GCN #30280,
Kumar et al. GCN #30286; Cunningham et al., GCN #30290)
with the SAO RAS 1-m telescope Zeiss-1000 + CCD-photometer.
We obtained 6 x 300 sec. frames in Rc band on June 20/21
(23:31:43--00:03:05 UT), T_mid-T0 = 0.99166d.

The OT is clearly detected in the stacked frame with the brightness
R = 19.8 +/- 0.1 (based on nearby USNO-B1 stars).


GRB_name: GRB210619B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30292
SUBJECT: GRB 210619B: iTelescope optical afterglow observation
DATE:    21/06/21 14:08:05 GMT
FROM:    Filipp Dmitrievich Romanov at Amateur astronomer  <filipp.romanov.27.04.1997@gmail.com>

I observed the field of GRB 210619B (D'Avanzo et al., GCN Circ. 30261)
using remote telescope T18 (0.32-m f/8.0 reflector + CCD) of
iTelescope.Net in observatory AstroCamp at Nerpio (Spain). Five images
(with exposures 300 seconds, BINx1) were obtained with Astrodon
luminance filter on 2021-06-20 from 23:06:46 to 23:36:44 UTC (until
the roof was closed due to poor weather).

I detected faint (SNR ~ 3) optical afterglow with UVOT position in
stacked image (mid time = 23:21:43 UTC, that is 0.974 days after the
trigger) and measured its magnitude from comparison to r' magnitudes
of nearby stars from Pan-STARRS DR1 catalogue (Chambers et al., 2016):
20.5 +/- 0.4. Magnitude was not corrected for Galactic extinction.

Stacked image available here:
https://www.flickr.com/photos/filipp-romanov/51261591951


GRB_name: GRB210619B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30293
SUBJECT: GRB 210619B: 1.5m OSN optical observation
DATE:    21/06/21 15:48:49 GMT
FROM:    Youdong HU at IAA-CSIC  <huyoudong072@hotmail.com>

Y.-D. Hu, A. Sota, T.-R. Sun, A. J. Castro-Tirado, M. D. Caballero-Garcia, M. A. Castro Tirado and E. Fernandez-Garcia (IAA-CSIC), on behalf of a larger collaboration, report:

Following the detection of GRB 210619B by Swift (D'Avanzo et al. GCN 30261), GECAM (Zhao et al. GCN 30264), CALET (Kawakubo et al. GCNC 30284), SRG/ART-XC (Levin et al. GCNC 30283), Fermi-LAT (Axelsson et al. GCNC 30270), Konus-Wind (Svinkin et al. GCN 30276) and Fermi/GBM (Poolakkil et al. GCNC 30279), images in BVRI bands were obtained at the 1.5m OSN telescope in Granada (Spain) starting on Jun 20, 22:33 UT. We detect the optical afterglow (Lipunov et al. GCNC 30259; Lipunov et al. GCNC 30262; Jelinek et al. GCNC 30263; Kong et al. GCNC 30265; Pellegrin et al. GCNC 30268; D. Perley GCNC 30271; de Ugarte Postigo et al. GCNC 30272; Zheng et al. GCNC 30273; Blazek et al. GCNC 30274; Kann et al. GCNC 30275; Xin et al. GCNC 30277; Kuin et al. GCNC 30278, Shrestha et al. GCNC 30280; Jelinek et al. GCNC 30281; Kumar et al. GCNC 30286; D'Avanzo et al. GCNC 30288; D'Avanzo et al. GCNC 30289; Cunningham et al. GCNC 30290; and Moskvitin et al. GCNC 30291) for which we measure R = 19.9 +/- 0.2 (~0.94 d after trigger). Further observations are ongoing.

We thank the staff at OSN for their excellent support.


GRB_name: GRB210619B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30294
SUBJECT: GRB 210619B: NOT optical observations
DATE:    21/06/21 16:41:37 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

Z.P. Zhu (NAOC, HUST), A. de Ugarte Postigo (HETH, IAA-CSIC), D. B. 
Malesani (DTU Space), L. Izzo (DARK/NBI), D. Alexander Kann (HETH, 
IAA-CSIC), D. Xu (NAOC), A. Amanda Djupvik (NOT) report on behalf of a 
larger collaboration:

We observed GRB 210619B detected by Swift/BAT (D'Avanzo et al., GCN 
30261) with the Nordic Optical Telescope (NOT) equipped with StanCAM. 
Observations started at 04:16:27 UT on 2021-06-21, and we obtained 3x300 
s exposures in the Bessel R filter, 5x200 s in the SDSS z-filter, and 
3x300 s in the i-filter (similar to SDSS i).

The previously reported optical afterglow (e.g., Lipunov et al. GCN 
30259; Zhao et al. GCN 30261; Jelinek et al. GCN 30263; Kong et al. GCN 
30265; Axelsson et al. GCN 30270; Perley et al. GCN 30271; de Ugarte 
Postigo et al. GCN 30272; Zheng et al. GCN 30273; Blazek et al. GCN 
30274; Kann et al. GCN 30275; Svinkin et al. GCN 30276; Xin et al. GCN 
30277; Shrestha et al. GCN 30280; Jelinek et al. GCN 30281; Kumar et 
al., GCN 30286; D'Avanzo et al., GCN 30288; D'Avanzo et al., GCN 30289; 
Moskvitin et al., GCN 30291; GCN 30292) is clearly detected in our 
images. Preliminary photometric results are as follows:

T_mid/d  Filter  Mag    MagErr MagSysten
1.18338 R 19.92      0.02     Vega
1.21390 i 19.65      0.02      AB
1.20022 z 18.88      0.11      AB

calibrated by the PS1 catalogue.


GRB_name: GRB210622A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30297
SUBJECT: GRB 210622A: Fermi GBM Final Real-time Localization
DATE:    21/06/22 01:42:57 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 01:32:35 UT on 22 Jun 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210622A (trigger 646018360.939998 / 210622064).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 242.1, Dec = -14.1 (J2000 degrees, equivalent to J2000 16h 08m, -14d 05'), with a statistical uncertainty of 6.1 degrees.

The angle from the Fermi LAT boresight is 82.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210622064/quicklook/glg_skymap_all_bn210622064.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210622064/quicklook/glg_healpix_all_bn210622064.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210622064/quicklook/glg_lc_medres34_bn210622064.gif


GRB_name: GRB210622B
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30298
SUBJECT: GRB 210622B: Fermi GBM Final Real-time Localization
DATE:    21/06/22 10:43:25 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 10:33:01 UT on 22 Jun 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210622B (trigger 646050786.759848 / 210622440).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 126.5, Dec = -13.1 (J2000 degrees, equivalent to J2000 08h 26m, -13d 05'), with a statistical uncertainty of 5.3 degrees.

The angle from the Fermi LAT boresight is 35.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210622440/quicklook/glg_skymap_all_bn210622440.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210622440/quicklook/glg_healpix_all_bn210622440.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210622440/quicklook/glg_lc_medres34_bn210622440.gif


GRB_name: GRB210619B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30299
SUBJECT: GRB 210619B: AbAO optical observations
DATE:    21/06/22 12:13:52 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

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

We observed the field of GRB 210619B (D'Avanzo et al., GCN 30261; Zhao 
et al., GCN 30264; Axelsson et al., GCN 30270; Svinkin et al., GCN 
30276; Levin et al., GCN 30283; Kawakubo et al., GCN 30284) with AS-32 
telescope of Abastumani observatory (AbAO) in R-filter on June, 21. The 
optical afterglow (Lipunov et al., GCN 30259; D'Avanzo et al., GCNs 
30261, 30288; Lipunov et al., GCN 30262; Jelinek et al., GCNs 30263, 
30281; Kong, GCN 30265; Pellegrin et al., GCN 30268, Perley et al., GCN 
30271; Zheng and Filippenko, GCN 30273; Blazek et al., GCN 30274; Kann 
et al., GCN 30275; Xin et al., GCN 30277; Shrestha et al., GCN 30280; 
Kumar et al., GCN 30286; Moskvitin et al., GCN 30291;  Romanov, GCN 
30292; Hu et al., GCN 30293; Zhu et al., GCN 30294) is detected in the 
stacked image. Preliminary photometry of the afterglow is following

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

2021-06-21 23:16:31   1.98931  R     55*60   20.6  0.3  20.6

The photometry is based on the nearby stars:
USNO-B1.0 R2
1238-0493928 15.08
1238-0494511 15.67


GRB_name: GRB210622B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30300
SUBJECT: GECAM detection of GRB 210622B
DATE:    21/06/22 12:39:19 GMT
FROM:    Chao Zheng at IHEP  <zhengchao97@ihep.ac.cn>

C. Zheng, S. L. Xiong, Y. Huang, S. L. Xie, S. Xiao, C. Cai, J. C. Liu,
C. Y. Li, Y. Q. Zhang, W. C. Xue, Y. Zhao, Z. W. Guo, X. Y. Zhao,
Z. H. An, C. Chen, G. Chen, W. Chen, M. Gao, K. Gong, D. Y. Guo, J. J. He,
B. Li, C. Li, J. H. Li, Q. X. Li, X. B. Li, X. Q. Li, Y. G. Li, X. H. Liang,
J. Y. Liao, J. C. Liu, X. J. Liu, Y. Q. Liu, F. J. Lu, Q. Luo, X. Ma,
G. Ou, W. X. Peng, R. Qiao, D. L. Shi, J. Y. Shi, L. M. Song,
X. Y. Song, G. X. Sun, X. L. Sun, Y. L. Tuo, C. W. Wang, J. Z. Wang,
P. Wang, X. Y. Wen, Y. B. Xu, Y. P. Xu, S. Yang, M. Yao, Q. B. Yi,
B. X. Zhang, C. Y. Zhang, D. L. Zhang, Fan Zhang, Fei Zhang, H. M. Zhang,
K. Zhang, P. Zhang, S. N. Zhang, Z. Zhang, S. Y. Zhao, S. J. Zheng,
X. Zhou (IHEP), report on behalf of GECAM team:

During the commissioning phase, GECAM-B was triggered in-flight by a long
burst at 2021-06-22T10:33:02.600 UTC (denoted as T0), which was also
observed by Fermi/GBM (GCN # 302298).

Its alert data was promptly downlinked to the ground through the short
message service of BeiDou Navigation Satellite System (BDS). The time
latency of the first BeiDou message relative to the trigger time is about
1 minute.

According to the BDS alert data, this burst mainly consists of multiple
pulses with duration of about 25 s. An automatic on-ground
localization was calculated using the light curves and spectrum. Although
the in-flight calibration of energy response and localization has not been
finalized yet, GECAM-B localized this burst to the following position (J2000): 
Ra: 123.9 deg
Dec: -13.8 deg
Err: 4.8 deg (1-sigma, statistical only)
The current systematic error of location is estimated to be several degrees 
which could be minimized by the ongoing calibration.

This GECAM location is consistent with that of Fermi/GBM within the error.

The GECAM light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/gecamb_lc_grd_all_combine_78057182.png

Please note that all GECAM results here are preliminary. The final analysis
will be published in journal papers or GECAM online catalog.

Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor
(GECAM) mission consists of two small satellites (GECAM-A and GECAM-B) in
Low Earth Orbit (600 km, 29 deg), launched on Dec 10, 2020 (Beijing Time),
which was funded by the Chinese Academy of Sciences (CAS).


GRB_name: GRB210619B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30301
SUBJECT: GRB 210619B: possibility of lensed visible afterglow?
DATE:    21/06/22 13:01:03 GMT
FROM:    Jean-Luc Atteia at IRAP  <jean-luc.atteia@irap.omp.eu>

Based on the fact that GRB 210619B (1) had a bright visible afterglow that remained above magnitude 20 for nearly one day (2), and considering the detection of an intervening system in its optical spectrum (3), we point out the possibility of lensed afterglow emission from this GRB, in the coming weeks or months (4), that could be detectable with moderate size telescopes.


(1) (D'Avanzo et al. GCN 30261 ; Zhao et al. GCN 30264 ; Kawakubo et al. GCNC 30284 ; Levin et al. GCNC 30283 ; Axelsson et al. GCNC 30270 ; Svinkin et al. GCN 30276 ; Poolakkil et al. GCNC 30279).

(2) (Lipunov et al. GCNC 30259; Lipunov et al. GCNC 30262; Jelinek et al. GCNC 30263; Kong et al. GCNC 30265; Pellegrin et al. GCNC 30268; D. Perley GCNC 30271; Zheng et al. GCNC 30273; Blazek et al. GCNC 30274; Kann et al. GCNC 30275; Xin et al. GCNC 30277; Kuin et al. GCNC 30278, Shrestha et al. GCNC 30280; Jelinek et al. GCNC 30281; Kumar et al. GCNC 30286; D'Avanzo et al. GCNC 30288; D'Avanzo et al. GCNC 30289; Cunningham et al. GCNC 30290; Moskvitin et al. GCNC 30291; Romanov GCNC 30292 ; 
Hu et al. GCNC 30293, Zhu et al. GCNC 30294).

(3) de Ugarte Postigo et al. GCNC 30272.

(4) Oguri, M. (2019) Reports on Progress in Physics, 82, 126901.


GRB_name: GRB210622A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30302
SUBJECT: GRB 210622A: Swift/BAT-GUANO detection and arcminute localization of a long burst
DATE:    21/06/22 13:59:39 GMT
FROM:    Aaron Tohuvavohu at U Toronto  <aaron.tohu@gmail.com>

James DeLaunay (PSU), Aaron Tohuvavohu (U Toronto), Jamie A. Kennea
(PSU), Gayathri Raman (PSU) report:

Swift/BAT did not trigger on GRB 210622A (T0: 2021-06-22 01:32:35.9
UTC, Fermi/GBM GCN 30297).

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

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

The burst is detected in BAT with a duration of at least 25 seconds.
We note this is different from the prompt GBM classification as â€˜likely shortâ€™.
The burst morphology consists of a first bright, short, hard, peak
followed by longer emission with weaker flares.

With a maximum likelihood analysis (DeLaunay et al. 2021, in prep.) on
the event-mode data we detect a location for the burst with a square
root of the test statistic, sqrt(TS), of 18.8. The sqrt(TS) behaves
similarly to SNR.
Using the normal BAT imaging technique, we find the same location for
the GRB with an SNR of 8.1.

The BAT position is
RA, Dec = 233.117, -26.213 deg which is
   RA(J2000)  = 15h 32m 28.10s
   Dec(J2000) =  -26d 12â€² 47.5â€³
with an estimated uncertainty of 2.5 arcmin.

This position is consistent with the Ferm/GBM localization (GCN 30297).

XRT and UVOT follow-up has been requested. Prompt followup by Swift is
delayed due to visibility constraints. 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: GRB210619B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30303
SUBJECT: GRB 210619B: Further SAO RAS optical observations
DATE:    21/06/22 14:07:24 GMT
FROM:    Moskvitin Alexander at SAO RAS  <mosk@sao.ru>

A. S. Moskvitin and O. A. Maslennikova (SAO RAS),
report on behalf of the GRB follow-up team.

We observed the field of Swift GRB 210619B (D'Avanzo et al.,
GCNs #30261, #30288, #30289; Jelinek et al., GCNs #30263, #30281;
Lipunov et al., GCN #30259; Zhao et al., GCN #30261; Kong et al.,
GCN #30265; Axelsson et al., #GCN 30270; de Ugarte Postigo et al.,
GCN #30272; Zheng et al., GCN #30273; Blazek et al., GCN #30274;
Kann et al., GCN #30275; Svinkin et al., GCN #30276; Xin et al.,
GCN #30277; Perley et al., GCN #30271, Shrestha et al., GCN #30280,
Kumar et al. GCN #30286; Cunningham et al., GCN #30290; Romanov,
GCN #30291; Hu et al., GCN #30293; Zhu et al., GCN #30294;
Belkin et al., GCN #30299; Atteia, GCN #30301)
with the SAO RAS 1-m telescope Zeiss-1000 + CCD-photometer.
We obtained 13 x 300 sec. frames in Rc band on June 21/22
(22:55:13--00:13:13 UT), T_mid-T0 = 1.98251d.

The OT is clearly detected in the stacked frame with the brightness
R = 20.73 +/- 0.08 (based on nearby USNO-B1 stars).


GRB_name: GRB210619B
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30304
SUBJECT: GRB 210619B: SPI-ACS/INTEGRAL observations
DATE:    21/06/22 16:17:53 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

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

We report observations of GRB 210619B with the INTEGRAL/SPI-ACS detector 
(publicly available data). The burst was previously detected in several 
X-/gamma-ray experiments (D'Avanzo et al., GCN 30261; Axelsson et al., 
GCN 30270; Poolakkil et al., GCN 30279; Levin et al., GCN 30283; 
Kawakubo et al., GCN 30284).
GRB 210619B  was detected by SPI-ACS at (UTC) 2021-06-19T23:59:25. Its 
duration in the SPI-ACS energy band (> 80 keV) is T_90 = 50.9 Â± 0.1 s. 
Comparing the fluxes measured from a number of long-duration GRBs 
simultaneously recorded by SPI-ACS and Fermi/GBM (Chelovekov et al., in 
preparation) we estimated the GRB 210619B fluence  to be 1.7e-4 erg/cm^2 
in the 10-1000 keV band (the 95% confidence region which includes 
systematics was 4.9e-5 - 5.9e-4 erg/cm^2). We did not detect any 
precursor with durations of 0.1 - 5 s during 500 s prior to the trigger 
time. Also we did not detect any signature of an extended emission up to 
1000 s after the trigger time. The SPI-ACS light curve of GRB 210619B 
can be found at
http://grb.rssi.ru/GRB210619B/GRB210619B_SPI-ACS_LC.png


GRB_name: GRB210619B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30305
SUBJECT: GRB 210619B: Abbey Ridge Observatory optical afterglow observation
DATE:    21/06/22 17:00:39 GMT
FROM:    Filipp Dmitrievich Romanov at Amateur astronomer  <filipp.romanov.27.04.1997@gmail.com>

Filipp D. Romanov (Russia) and David J. Lane (Saint Mary's University,
Canada) report:

Filipp Romanov observed optical afterglow of GRB 210619B (D'Avanzo et
al., GCN Circ. 30261) remotely using 0.355-m f/6.2 Schmidt-Cassegrain
telescope of Abbey Ridge Observatory (it is owned by Dave Lane) in
Canada, on 2021-06-21.

Eight images (with exposures: 660, 840, 720, 840, 720, 720, 780 and
720 seconds) were obtained with Cousins R filter from 02:29:26 to
04:56:00 UTC. The optical afterglow (with UVOT position) is clearly
(SNR = 11) visible in the stacked image (mid time = 03:42:42 UTC, that
is 1.155 days after the trigger). Romanov measured its magnitude
comparing to transformed (using formula Rc=râ€™-0.22 from Dymock &
Miles, 2009) r' magnitudes of nearby stars from Pan-STARRS DR1
catalogue (Chambers et al., 2016). The measured magnitude = 20.0 +/-
0.2. Magnitude was not corrected for Galactic extinction.

Stacked image available here:
http://www.abbeyridgeobservatory.ca/images/GRB210619B.jpg


GRB_name: GRB210622A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30306
SUBJECT: GRB 210622A: Fermi GBM detection
DATE:    21/06/22 22:08:07 GMT
FROM:    Stephen Lesage at Fermi-GBM Team  <sjl0014@uah.edu>

S. Lesage (UAH) and R. Hamburg (UAH)
report on behalf of the Fermi GBM Team:

"At 01:32:35.94 UT on 22 June 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210622A (trigger 646018360 / 210622064)
which was also detected by the Swift/BAT-GUANO (DeLaunay et al. 2021, GCN 30302)
The Fermi GBM Final Real-time Localization (GCN 30297) is consistent
with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 97 degrees.

The GBM light curve consists of a single peak followed by some
extended emission with a duration (T90) of about 40 s (50-300 keV).
The time-averaged spectrum from T0 s to T0+39.4 s
is best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.8 +/- 0.2 and
the cutoff energy, parameterized as Epeak, is 376 +/- 98 keV.

The event fluence (10-1000 keV) in this time interval is
(1.01 +/- 0.12)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.128 s in the 10-1000 keV band
is 3.1 +/- 0.2 ph/s/cm^2.

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

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


GRB_name: GRB210622B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30307
SUBJECT: Fermi GRB 210622B: Global MASTER-Net observations report 
DATE:    21/06/22 23:17:27 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

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

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

D. Buckley 
(South African Astronomical Observatory),

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

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

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




MASTER-OAFA robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 210622B ( Fermi GBM team, GCN 30298) errorbox  43469 sec after notice time and 43496 sec after trigger time at 2021-06-22 22:37:57 UT, with upper limit up to  17.8 mag. Observations started at twilight.  The observations began at zenith distance = 56 deg. The sun  altitude  is -12.0 deg. 

The galactic latitude b = 15 deg., longitude l = 237 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1642370

We obtain a following upper limits.  

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

   43526 | 2021-06-22 22:37:57 |         MASTER-OAFA | (08h 14m 05.24s , -14d 37m 45.1s) |   C |    60 | 17.4 |        
   43605 | 2021-06-22 22:39:17 |         MASTER-OAFA | (08h 22m 14.70s , -14d 38m 34.0s) |   C |    60 | 17.4 |        
   43685 | 2021-06-22 22:40:36 |         MASTER-OAFA | (08h 25m 46.77s , -12d 42m 57.2s) |   C |    60 | 17.6 |        
   43767 | 2021-06-22 22:41:58 |         MASTER-OAFA | (08h 33m 57.71s , -12d 44m 12.9s) |   C |    60 | 17.8 |        
   43847 | 2021-06-22 22:43:18 |         MASTER-OAFA | (08h 10m 11.95s , -12d 43m 46.8s) |   C |    60 | 17.8 |        
   43926 | 2021-06-22 22:44:37 |         MASTER-OAFA | (08h 18m 21.69s , -12d 42m 35.5s) |   C |    60 | 17.8 |        
   44006 | 2021-06-22 22:45:57 |         MASTER-OAFA | (08h 29m 39.40s , -14d 38m 20.6s) |   C |    60 | 17.6 |        
   44085 | 2021-06-22 22:47:17 |         MASTER-OAFA | (08h 38m 00.16s , -14d 38m 01.8s) |   C |    60 | 17.8 |        
   44165 | 2021-06-22 22:48:36 |         MASTER-OAFA | (08h 18m 29.20s , -16d 32m 12.2s) |   C |    60 | 17.7 |        
   44244 | 2021-06-22 22:49:56 |         MASTER-OAFA | (08h 26m 51.96s , -16d 30m 43.5s) |   C |    60 | 17.6 |        
   44783 | 2021-06-22 22:58:54 |         MASTER-OAFA | (08h 14m 00.60s , -14d 36m 33.1s) |   C |    60 | 17.8 |        
   44862 | 2021-06-22 23:00:14 |         MASTER-OAFA | (08h 22m 20.98s , -14d 37m 22.9s) |   C |    60 | 17.7 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB210619B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30308
SUBJECT: GRB 210619B: Mini-MegaTORTORA early optical observations
DATE:    21/06/23 11:18:23 GMT
FROM:    Sergey Karpov at SAO RAS  <karpov@sao.ru>

S.Karpov (FZU CAS, Czech Republic; SAO RAS and Kazan Federal University,
Russia)
G.Beskin (SAO RAS and Kazan Federal University, Russia),
N. Lyapsina (SAO RAS, Russia),
E.Ivanov, E.Katkova, A.Perkov (OJS RPC PSI, Russia),
A.Biryukov (SAI MSU and Kazan Federal University, Russia),
V.Sasyuk (Kazan Federal University, Russia)

Mini-MegaTORTORA nine-channel wide-field monitoring system  with high
temporal resolution responded to the BAT trigger and observed the position
of GRB 210619B (D'Avanzo et al., GCN 30261) since 2021-06-20 00:00:20 UT
(T+55 s, during the ongoing gamma-ray emission) and until 2021-06-20
00:10:28 UT (T + 663 s). The system simultaneously acquired series of
frames with 1 s exposures, 5 s exposures and 30 s exposures in white light,
10 s exposures in B filter, and 10 s exposures in V filter.

The transient was clearly detectable in all acquired sequences except B
filter ones. Overall behaviour of the early light curve is consistent with
the smooth decay reported by Jelinek et al. (GCN 30263), with no
large-amplitude variability apparent in high temporal resolution data.

Mini-MegaTORTORA belongs to Kazan Federal University and is located at
Special Astrophysical Observatory near Russian 6-m telescope.

The message may be cited.


GRB_name: GRB210619B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30309
SUBJECT: GRB 210619B: Even further SAO RAS optical observations
DATE:    21/06/23 13:34:33 GMT
FROM:    Moskvitin Alexander at SAO RAS  <mosk@sao.ru>

A. S. Moskvitin and O. A. Maslennikova (SAO RAS),
report on behalf of the GRB follow-up team.

We observed the field of Swift GRB 210619B (D'Avanzo et al.,
GCNs #30261, #30288, #30289; Jelinek et al., GCNs #30263, #30281;
Lipunov et al., GCN #30259; Zhao et al., GCN #30261; Kong et al.,
GCN #30265; Axelsson et al., #GCN 30270; de Ugarte Postigo et al.,
GCN #30272; Zheng et al., GCN #30273; Blazek et al., GCN #30274;
Kann et al., GCN #30275; Svinkin et al., GCN #30276; Xin et al.,
GCN #30277; Perley et al., GCN #30271, Shrestha et al., GCN #30280,
Kumar et al. GCN #30286; Cunningham et al., GCN #30290; Romanov,
GCN #30291; Hu et al., GCN #30293; Zhu et al., GCN #30294;
Belkin et al., GCN #30299; Atteia, GCN #30301, Minaev et al.,
GCN #30304; Romanov & Lane, GCN #30305; Karpov et al., GCN #30308)
with the SAO RAS 1-m telescope Zeiss-1000 + CCD-photometer.
We obtained 12 x 300 sec. frames in Rc band on June 22
(22:26:19--23:45:27 UT), T_mid-T0 = 2.96283d.

The OT is clearly detected in the stacked frame with the brightness
R = 21.4 +/- 0.1 (based on nearby USNO-B1 stars).


GRB_name: GRB210622A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30310
SUBJECT: GRB 210622A: Swift ToO observations
DATE:    21/06/24 01:06:05 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

Swift has initiated a ToO observation of the Swift/BAT-GUANO GRB 210622A. 
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021452

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 Swift/BAT-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: GRB210618A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30312
SUBJECT: GRB 210618A: Swift-XRT afterglow detection
DATE:    21/06/24 09:18:30 GMT
FROM:    Maria Grazia Bernardini at INAF/Brera  <grazia.bernardini@brera.inaf.it>

J.P. Osborne (U. Leicester), 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), A. Tohuvavohu (U.
Toronto), B. Sbarufatti (PSU) and P.A. Evans (U. Leicester) report on
behalf of the Swift-XRT team:

Swift-XRT has conducted further observations of the field of the
Swift-BAT-detected burst GRB 210618A (Bernardini et al. GCN Circ.
30250). The observations now extend from T0+3.7 ks to T0+424.9 ks. 

Of the sources reported by Osborne et al. (GCN Circ. 30252), "Source 2"
is believed to be the afterglow.  The position of this source is RA,
Dec=235.7698, +46.0691 which is equivalent to:

RA (J2000): 15:43:04.75
Dec(J2000): +46:04:08.6

with an uncertainty of 9.3 arcsec (radius, 90% confidence).  This
position is 2.6 arcmin from the Swift-BAT position.  The results of the
XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01056426.
The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/ToO_GRBs/01056426.

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


GRB_name: GRB210619B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30315
SUBJECT: GRB 210619B: ASIM observation
DATE:    21/06/25 07:18:32 GMT
FROM:    Martino Marisaldi at U of Bergen, Norway  <martino.marisaldi@uib.no>

M. Marisaldi (University of Bergen), A. Mezentsev (University of Bergen), 
N. Ã˜stgaard (University of Bergen), V. Reglero (University of Valencia) 
and T. Neubert (DTU Space) report on behalf of the ASIM Team:

At 23:59:27.928 UT on 19 June 2021, the Atmosphere-Space Interactions Monitor (ASIM)
mission triggered on the long bright GRB 210619B 
(Swift detection: Dâ€™Avanzo et al., GCN Circ. 30261; GECAM detection: Zhao et al., GCN Circ. 30264;
Fermi-LAT detection: Axelsson et al., GCN Circ. 30270; Konus-Wind detection: Svinkin et al., GCN Circ. 30276; 
Fermi GBM detection: Poolakkil et al., GCN Circ. 30279; CALET detection: Kawakubo et al., GCN Circ. 30284; 
SPI-ACS/INTEGRAL detection: Minaev et al., GCN Circ. 30304)

Photon by photon data with <1 microsecond time resolution have been
collected for a time interval of five seconds.
As seen by the Modular X- and Gamma-Ray Sensor (MXGS) onboard ASIM
the burst consists of a single emission episode. 
The emission is detected in the MXGS High Energy Detector (HED), sensitive in the range 0.3 to >30 MeV.  
The MXGS Low Energy Detector (LED), sensitive in the range 0.05 to 0.4 MeV, 
was not active at trigger time.

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 <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 <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 <https://doi.org/10.1007/s11214-019-0593-y>  ). 
The ASIM Science Data Centre (ASDC) website is https://asdc.space.dtu.dk/ <https://asdc.space.dtu.dk/>


GRB_name: GRB210610B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30316
SUBJECT: GRB 210610B: T-CAT optical observations
DATE:    21/06/25 14:40:15 GMT
FROM:    Denis Marchais at Amateur astronomer  <denis.marchais@free.fr>

I observed the field of GRB 210610B (Page et al., GCN #30170) with the
T-CAT telescope 0.4-meter f/4 Newton with a f/3 reducer, IR-cut filter
at 630nm and ZWO ASI533MC camera, located in Cintegabelle, France, on
June 11, 12 and 13.

The camera has a Sony sensor with Bayer filters R,G,B, that fairly 
match the standard Bc, Vc, and r' filters considering the additional
IR-cut filter. Each observation results from stacking 120x 32s exposures.

The GRB OT is clearly detected in the stacked frames at the following
location, matching other observations (e.g. , Fynho et al. GCN #30182,
Osborne et al. GCN #30186) though approaching the detection limit on
third observation, June 13th.
   RA(J2000)  = 16h 15m 40.39s
   Dec(J2000) = +14d 23' 56.3"

The following magnitudes were obtained thanks to PixInsight photometric 
calibration using nearby APASS DR10 stars.

Date        UT start     Filter   Exp. (s)    OT     err
2021-06-11  23:52:21     Bc       120x 32     20.53  +/- 0.05
2021-06-11  23:52:21     Vc       120x 32     20.00  +/- 0.04
2021-06-11  23:52:21     r'       120x 32     19.64  +/- 0.04
2021-06-12  22:48:22     Bc       120x 32     21.79  +/- 0.11
2021-06-12  22:48:22     Vc       120x 32     20.91  +/- 0.07
2021-06-12  22:48:22     r'       120x 32     20.90  +/- 0.10
2021-06-13  22:45:36     Bc       120x 32     21.77  +/- 0.1
2021-06-13  22:45:36     Vc       120x 32     21.42  +/- 0.09
2021-06-13  22:45:36     r'       120x 32     21.76  +/- 0.2

I thank A. Taylor, H.-B. Eggenstein and E. Broens (GCN#30205) for sharing
information through the KNCatcher citizen-science programme initiated by
S. Antier and A. Klotz as part of GRANDMA initiative (GRANDMA Observations
of Advanced LIGO's and Advanced Virgo's Third Observational Campaign,
Antier et al. https://arxiv.org/abs/2004.04277v2).


GRB_name: GRB210622A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30317
SUBJECT: GRB 210622A: Swift-XRT observations
DATE:    21/06/25 16:02:37 GMT
FROM:    Antonino D'Ai at IASF-PA  <antonino.dai@inaf.it>

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

Swift-XRT has performed follow-up observations of the
Swift/BAT-GUANO-detected burst GRB 210622A (James DeLaunay et al. GCN
Circ. 30302), collecting 4.5 ks of Photon Counting (PC) mode data
between T0+171.2 ks and T0+221.6 ks. 

No X-ray sources have been detected consistent with being within 246
arcsec of the Swift/BAT-GUANO position. The 3-sigma upper limit in the
field is 0.003 ct  s^-1, corresponding to a 0.3-10 keV observed flux of
1.0e-13 erg cm^-2 s^-1 (assuming a typical GRB spectrum).

An uncatalogued was detected, however this was too far from the GRB
position to be the afterglow.

The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
https://www.swift.ac.uk/ToO_GRBs/00021452.

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


GRB_name: GRB210624A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30318
SUBJECT: IPN triangulation of GRB 210624A (short)
DATE:    21/06/25 17:36:45 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

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

K. Hurley, on behalf of the IPN,

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

and

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,
report:

The short-duration GRB 210624A
was detected by Fermi (GBM trigger 646189108), Konus-Wind,
and INTEGRAL (SPI-ACS) at about 3503 s UT (00:58:23).

We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
    54.243 (03h 36m 58s) +80.364 (+80d 21' 49")
  Corners:
    50.629 (03h 22m 31s) +77.944 (+77d 56' 38")
    48.706 (03h 14m 49s) +77.917 (+77d 55' 01")
    60.700 (04h 02m 48s) +82.723 (+82d 43' 23")
    63.941 (04h 15m 46s) +82.672 (+82d 40' 18")
  ---------------------------------------------
The error box area is 1.96 sq. deg, and its maximum
dimension is 5.36 deg (the minimum one is 22.7 arcmin).
The Sun distance was 58 deg.

This box may be improved.

The IPN localization is consistent with, but reduces the area of,
the Fermi final position.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB210624_T03500/IPN

The time history and spectrum will be given in forthcoming GCN Circulars.


GRB_name: GRB210625A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30319
SUBJECT: GRB 210625A: Fermi GBM Final Real-time Localization
DATE:    21/06/25 21:33:39 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 21:23:21 UT on 25 Jun 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210625A (trigger 646349006.139788 / 210625891).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 247.5, Dec = -41.0 (J2000 degrees, equivalent to J2000 16h 30m, -41d 00'), with a statistical uncertainty of 7.6 degrees.

The angle from the Fermi LAT boresight is 26.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210625891/quicklook/glg_skymap_all_bn210625891.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210625891/quicklook/glg_healpix_all_bn210625891.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210625891/quicklook/glg_lc_medres34_bn210625891.gif


GRB_name: GRB210619B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30320
SUBJECT: GRB210619B: optical afterglow detection from Konkoly Observatory
DATE:    21/06/25 21:54:22 GMT
FROM:    Jozsef Vinko at Konkoly Observator  <vinko@konkoly.hu>

J. Vinko, L. Kriskovics, A. Pal, R. Szakats, K. Vida, Zs. Szabo, R. Konyves-Toth, M. Krezinger and K. Sarneczky (Konkoly Observatory, Hungary) report:

We observed the field of GRB210619B
(D'Avanzo et al.,GCN #30261, #30288, #30289; Jelinek et al., GCN #30263, #30281;
Lipunov et al., GCN #30259; Zhao et al., GCN #30261; Kong et al.,
GCN #30265; Axelsson et al., #GCN 30270; de Ugarte Postigo et al.,
GCN #30272; Zheng et al., GCN #30273; Blazek et al., GCN #30274;
Kann et al., GCN #30275; Svinkin et al., GCN #30276; Xin et al.,
GCN #30277; Perley et al., GCN #30271, Shrestha et al., GCN #30280,
Kumar et al. GCN #30286; Cunningham et al., GCN #30290; Romanov,
GCN #30291; Hu et al., GCN #30293; Zhu et al., GCN #30294;
Belkin et al., GCN #30299; Atteia, GCN #30301, Minaev et al.,
GCN #30304; Romanov & Lane, GCN #30305; Karpov et al., GCN #30308;
Moskvitin & Maslennikova, GCN #30309; Marisaldi et al., GCN #30315)
with the RC80 robotic telescope at Piszkesteto Station of Konkoly
Observatory on 2021 June 22 starting at 22:46:41.5 UT. A series of 5x300 sec
frames were collected through Sloan r'- and i' bands. The optical afterglow
was detected with the following magnitudes calibrated via nearby PS1 stars:

Date         UT-middle   t-T0(hr)  Exp(s)   r'(mag)           i'(mag)
2021-06-22   23:07:16    71.13     5x300    21.454 +/-0.333   20.089 +/-0.280

Follow-up observations on 2021-06-23 starting at 21:34:37.7 UT (3.90 days post-trigger)
resulted in no detection down to limiting magnitudes of r'=22.14 and i'=21.98 mag.


GRB_name: GRB210625A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30321
SUBJECT: Fermi GRB 210625A: Global MASTER-Net observations report 
DATE:    21/06/25 23:05:14 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

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

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

D. Buckley 
(South African Astronomical Observatory),

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

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

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




MASTER-IAC robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Spain (IAC Teide Observatory) started inspect of the Fermi GRB 210625A ( Fermi GBM team, GCN 30319) errorbox  1261 sec after notice time and 1355 sec after trigger time at 2021-06-25 21:45:56 UT, with upper limit up to  16.7 mag. The observations began at zenith distance = 71 deg. The sun  altitude  is -19.6 deg. 

MASTER-OAFA robotic telescope  located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 210625A errorbox  4020 sec after notice time and 4114 sec after trigger time at 2021-06-25 22:31:55 UT, with upper limit up to  16.3 mag. Observations started at twilight.  The observations began at zenith distance = 55 deg. The sun  altitude  is -10.7 deg. 

The galactic latitude b =  5 deg., longitude l = 341 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1644880

We obtain a following upper limits.  

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

    1386 | 2021-06-25 21:45:56 |          MASTER-IAC | (16h 24m 25.20s , -40d 31m 27.3s) |   C |    60 | 16.7 |        
    1386 | 2021-06-25 21:45:56 |          MASTER-IAC | (16h 13m 53.49s , -40d 25m 50.0s) |   C |    60 | 16.5 |        
    1467 | 2021-06-25 21:47:18 |          MASTER-IAC | (16h 33m 17.35s , -42d 26m 47.4s) |   C |    60 | 16.7 |        
    1467 | 2021-06-25 21:47:18 |          MASTER-IAC | (16h 22m 26.85s , -42d 21m 11.0s) |   C |    60 | 16.5 |        
    1547 | 2021-06-25 21:48:38 |          MASTER-IAC | (16h 44m 26.10s , -40d 34m 09.7s) |   C |    60 | 16.4 |        
    1547 | 2021-06-25 21:48:38 |          MASTER-IAC | (16h 33m 54.14s , -40d 28m 33.9s) |   C |    60 | 16.5 |        
    4144 | 2021-06-25 22:31:55 |         MASTER-OAFA | (16h 43m 49.19s , -39d 20m 37.5s) |   C |    60 | 13.6 |        
    4303 | 2021-06-25 22:34:34 |         MASTER-OAFA | (16h 20m 16.83s , -46d 55m 09.0s) |   C |    60 | 12.2 |        
    4382 | 2021-06-25 22:35:53 |         MASTER-OAFA | (16h 31m 50.58s , -46d 57m 05.9s) |   C |    60 | 13.5 |        
    4462 | 2021-06-25 22:37:12 |         MASTER-OAFA | (15h 58m 15.24s , -46d 55m 21.8s) |   C |    60 | 16.3 |        
    4541 | 2021-06-25 22:38:32 |         MASTER-OAFA | (16h 09m 49.77s , -46d 54m 40.3s) |   C |    60 | 15.6 |        
    4620 | 2021-06-25 22:39:51 |         MASTER-OAFA | (15h 47m 49.38s , -45d 02m 04.1s) |   C |    60 | 16.0 |        
    4700 | 2021-06-25 22:41:11 |         MASTER-OAFA | (15h 59m 06.20s , -45d 02m 10.7s) |   C |    60 | 16.0 |        
    4779 | 2021-06-25 22:42:30 |         MASTER-OAFA | (16h 42m 15.43s , -46d 57m 07.4s) |   C |    60 | 13.7 |        
    4860 | 2021-06-25 22:43:50 |         MASTER-OAFA | (16h 53m 52.94s , -46d 56m 21.1s) |   C |    60 | 15.4 |        
    4939 | 2021-06-25 22:45:10 |         MASTER-OAFA | (16h 51m 33.32s , -45d 01m 53.0s) |   C |    60 | 15.3 |        
    5019 | 2021-06-25 22:46:29 |         MASTER-OAFA | (17h 02m 50.38s , -45d 03m 13.9s) |   C |    60 | 14.1 |        
    5098 | 2021-06-25 22:47:49 |         MASTER-OAFA | (16h 43m 44.44s , -39d 21m 39.0s) |   C |    60 | 13.9 |        
    5179 | 2021-06-25 22:49:09 |         MASTER-OAFA | (16h 54m 03.63s , -39d 21m 28.4s) |   C |    60 | 12.2 |        
    5258 | 2021-06-25 22:50:29 |         MASTER-OAFA | (16h 20m 17.35s , -46d 55m 04.3s) |   C |    60 | 12.9 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB210618A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30322
SUBJECT: GRB 210618A: 1.5m OSN optical upper limit
DATE:    21/06/26 02:18:04 GMT
FROM:    Youdong HU at IAA-CSIC  <huyoudong072@hotmail.com>

Y.-D. Hu, F. J. Aceituno, T.-R. Sun, A. J. Castro-Tirado, M. D. Caballero-Garcia, M. A. Castro Tirado and E. Fernandez-Garcia (IAA-CSIC) on behalf of a larger collaboration, report:

Following the detection of GRB210618A by Swift (Bernardini et al. GCNC 30250) and Fermi (Fermi GBM team. GCNC 30248), we triggered the 1.5m OSN telescope in Granada (Spain) for the possible X-ray afterglow detection, "Source 2" reported in Osborne et al. GCNC 30252. Optical images in the I-band were obtained starting on Jun 24, 21:11 UT (~6.8 d after trigger). No-optical afterglow is detected in the co-added image (300s x 3) within the Swift/XRT error box (Osborne et al. GCNC 30312) which down to I=20.9.

We thank the staff at OSN for their excellent support.


GRB_name: GRB210626A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30323
SUBJECT: GRB 210626A: Fermi GBM Final Real-time Localization
DATE:    21/06/26 08:26:33 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 08:16:15 UT on 26 Jun 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210626A (trigger 646388180.992174 / 210626345).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 216.0, Dec = -4.2 (J2000 degrees, equivalent to J2000 14h 24m, -4d 12'), with a statistical uncertainty of 3.9 degrees.

The angle from the Fermi LAT boresight is 76.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210626345/quicklook/glg_skymap_all_bn210626345.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210626345/quicklook/glg_healpix_all_bn210626345.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210626345/quicklook/glg_lc_medres34_bn210626345.gif


GRB_name: GRB150428A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30324
SUBJECT: GRB 150428A: late-time radio observations
DATE:    21/06/26 13:58:18 GMT
FROM:    James Leung at U of Sydney/VAST  <jleu9465@uni.sydney.edu.au>

James Leung (University of Sydney/CSIRO), Poonam Chandra (NCRA-TIFR),
Emil Lenc (CSIRO), Tara Murphy (University of Sydney), Ziteng Wang
(University of Sydney/CSIRO)

ASKAP J123409+065712 is a radio source found in a search of
Australian Square Kilometre Array Pathfinder (ASKAP) data (SB10736).
The radio source position is consistent with the enhanced Swift-XRT
position (Osborne et al., GCN Circ. 17768) and inconsistent with the
GROND source position (Knust et al., GCN Circ. 17767).

We conducted further observations of the radio source with the
Australia Telescope Compact Array (ATCA) and the upgraded Giant
Metrewave Radio Telescope (uGMRT). We summarise these observations in
the table below.

Date (UTC) | Telescope | Freq (GHz) | Peak Flux Density (uJy/beam)
------------------------------------------------------------------
2019/12/05 | ASKAP     | 1.4        | 363 +/- 56
2021/05/21 | ATCA      | 5.5        |  94 +/- 26
2021/06/13 | uGMRT     | 1.3        | 386 +/- 17

The fitted position of the radio source from the uGMRT observation is
RA: 12:34:09.296
Dec: +06:57:13.83

Observations of the radio source do not show any evidence for fading
in epochs separated by 555 days and we therefore conclude the source
is likely the host galaxy of GRB 150428A.

We thank CSIRO and GMRT staff for supporting these observations
during these especially difficult times.


GRB_name: GRB210626A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30325
SUBJECT: GRB 210626A: Swift/BAT-GUANO detection and arcminute localization
DATE:    21/06/26 15:32:38 GMT
FROM:    Aaron Tohuvavohu at U Toronto  <aaron.tohu@gmail.com>

Aaron Tohuvavohu (U Toronto), James DeLaunay (PSU), Jamie A. Kennea
(PSU), Gayathri Raman (PSU) report:

Swift/BAT did not trigger on GRB 210626A (T0: 2021-06-26 08:16:15.9
UTC, Fermi/GBM GCN 30323).

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

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

The burst is detected in BAT with a duration greater than 20 seconds.
The burst occurred during a Swift slew.
Using the normal BAT imaging technique, we find the location for
the GRB with an SNR of 7.6.

The BAT position is
RA, Dec = 221.6199,  -1.1512 deg which is
   RA(J2000)  = 14h 46m 28.78s
   Dec(J2000) =  -1d 09â€² 4.3â€³
with an estimated uncertainty of 5 arcmin.

This position is consistent with the Ferm/GBM localization (GCN 30323).

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: GRB210626A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30326
SUBJECT: GRB 210626A: Swift ToO observations
DATE:    21/06/26 16:30:23 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

Swift has initiated a ToO observation of the Swift/BAT-GUANO GRB 210626A. 
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021453

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 Swift/BAT-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: GRB210626A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30327
SUBJECT: Fermi GRB 210626A: Global MASTER-Net observations report 
DATE:    21/06/26 21:16:42 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

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

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

D. Buckley 
(South African Astronomical Observatory),

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

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

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




MASTER-IAC robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Spain (IAC Teide Observatory) started inspect of the Fermi GRB 210626A ( Fermi GBM team, GCN 30323) errorbox  45371 sec after notice time and 45494 sec after trigger time at 2021-06-26 20:54:30 UT, with upper limit up to  18.5 mag. Observations started at twilight.  The observations began at zenith distance = 33 deg. The sun  altitude  is -10.6 deg. 

The galactic latitude b = 51 deg., longitude l = 343 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1645256

We obtain a following upper limits.  

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

   45524 | 2021-06-26 20:54:30 |          MASTER-IAC | (14h 31m 35.31s , -04d 23m 21.9s) |   C |    60 | 17.3 |        
   45524 | 2021-06-26 20:54:30 |          MASTER-IAC | (14h 23m 30.29s , -04d 17m 54.2s) |   C |    60 | 16.8 |        
   45604 | 2021-06-26 20:55:49 |          MASTER-IAC | (14h 29m 54.51s , -02d 30m 25.6s) |   C |    60 | 17.3 |        
   45604 | 2021-06-26 20:55:49 |          MASTER-IAC | (14h 21m 50.29s , -02d 24m 57.4s) |   C |    60 | 17.1 |        
   45684 | 2021-06-26 20:57:09 |          MASTER-IAC | (14h 19m 03.53s , -06d 19m 19.7s) |   C |    60 | 17.5 |        
   45684 | 2021-06-26 20:57:09 |          MASTER-IAC | (14h 10m 57.01s , -06d 13m 53.3s) |   C |    60 | 17.3 |        
   45763 | 2021-06-26 20:58:29 |          MASTER-IAC | (14h 16m 27.27s , -04d 25m 15.0s) |   C |    60 | 17.6 |        
   45763 | 2021-06-26 20:58:29 |          MASTER-IAC | (14h 08m 22.21s , -04d 19m 48.0s) |   C |    60 | 17.5 |        
   45843 | 2021-06-26 20:59:49 |          MASTER-IAC | (14h 34m 23.49s , -06d 17m 53.6s) |   C |    60 | 17.7 |        
   45843 | 2021-06-26 20:59:49 |          MASTER-IAC | (14h 26m 16.98s , -06d 12m 26.1s) |   C |    60 | 17.5 |        
   45924 | 2021-06-26 21:01:09 |          MASTER-IAC | (14h 29m 01.44s , -00d 37m 28.8s) |   C |    60 | 18.1 |        
   45924 | 2021-06-26 21:01:09 |          MASTER-IAC | (14h 20m 57.52s , -00d 32m 00.3s) |   C |    60 | 17.9 |        
   46004 | 2021-06-26 21:02:30 |          MASTER-IAC | (14h 14m 40.67s , -02d 29m 37.6s) |   C |    60 | 18.1 |        
   46004 | 2021-06-26 21:02:30 |          MASTER-IAC | (14h 06m 36.35s , -02d 24m 10.3s) |   C |    60 | 17.5 |        
   46084 | 2021-06-26 21:03:50 |          MASTER-IAC | (14h 22m 43.90s , -08d 12m 29.4s) |   C |    60 | 17.9 |        
   46084 | 2021-06-26 21:03:50 |          MASTER-IAC | (14h 14m 35.23s , -08d 07m 03.1s) |   C |    60 | 17.7 |        
   46164 | 2021-06-26 21:05:10 |          MASTER-IAC | (14h 13m 45.82s , -00d 35m 27.8s) |   C |    60 | 18.5 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB210626A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30329
SUBJECT: GRB 210626A: Swift-XRT afterglow detection
DATE:    21/06/27 00:08:12 GMT
FROM:    Aaron Tohuvavohu at U Toronto  <aaron.tohu@gmail.com>

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

Swift-XRT has performed follow-up observations of the
Swift/BAT-GUANO-detected burst GRB 210626A (Aaron Tohuvavohu et al. GCN
Circ. 30325), collecting 1.4 ks of Photon Counting (PC) mode data
between T0+29.7 ks and T0+31.1 ks. 

An uncatalogued X-ray source is detected and is above the 2SXPS 3-sigma
upper limit at this position, and is therefore likely the GRB
afterglow. Using 1180 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 = 221.52429, -1.15625
which is equivalent to:

RA (J2000): 14h 46m 05.83s
Dec(J2000): -01d 09' 22.5"

with an uncertainty of 5.7 arcsec (radius, 90% confidence). This
position is 5.7 arcmin from the Swift/BAT-GUANO position.  We cannot
determine at the present time whether the source is fading.

The results of the XRT-team automatic analysis of the likely afterglow
are at https://www.swift.ac.uk/ToO_GRBs/00021453/Source1.php.
The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/ToO_GRBs/00021453.

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


GRB_name: GRB210627A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30330
SUBJECT: GRB 210627A: Fermi GBM Final Real-time Localization
DATE:    21/06/27 07:39:37 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM  <do_not_reply@GIOC.nsstc.nasa.gov>

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

At 07:29:15 UT on 27 Jun 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210627A (trigger 646471760.677184 / 210627312).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 148.3, Dec = 44.5 (J2000 degrees, equivalent to J2000 09h 53m, 44d 30'), with a statistical uncertainty of 10.7 degrees.

The angle from the Fermi LAT boresight is 109.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210627312/quicklook/glg_skymap_all_bn210627312.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210627312/quicklook/glg_healpix_all_bn210627312.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210627312/quicklook/glg_lc_medres34_bn210627312.gif


GRB_name: GRB210627A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30331
SUBJECT: Fermi GRB 210627A: Global MASTER-Net observations report 
DATE:    21/06/27 17:31:26 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

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

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

D. Buckley 
(South African Astronomical Observatory),

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

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

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




MASTER-SAAO robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 210627A ( Fermi GBM team, GCN 30330) errorbox  34547 sec after notice time and 34584 sec after trigger time at 2021-06-27 17:05:39 UT, with upper limit up to  18.0 mag. Observations started at twilight.  The observations began at zenith distance = 79 deg. The sun  altitude  is -16.9 deg. 

The galactic latitude b = 51 deg., longitude l = 175 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1646025

We obtain a following upper limits.  

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

   28421 | 2021-06-27 15:22:27 |             MASTER- | (09h 55m 25.25s , +49d 43m 07.7s) |   C |    60 | 12.0 |        
   28501 | 2021-06-27 15:23:46 |             MASTER- | (10h 09m 19.79s , +50d 48m 46.6s) |   C |    60 | 17.2 |        
   28603 | 2021-06-27 15:25:45 |             MASTER- | (10h 06m 03.52s , +50d 14m 34.0s) |   C |    25 | 14.7 |        
   28827 | 2021-06-27 15:29:25 |             MASTER- | (09h 53m 35.33s , +48d 11m 37.7s) |   C |    35 | 12.5 |        
   28827 | 2021-06-27 15:29:25 |             MASTER- | (10h 04m 46.52s , +49d 27m 54.1s) |   C |    35 | 13.9 |        
   28875 | 2021-06-27 15:30:10 |             MASTER- | (09h 30m 40.50s , +48d 08m 49.0s) |   C |    40 | 13.4 |        
   28875 | 2021-06-27 15:30:10 |             MASTER- | (09h 41m 41.44s , +49d 25m 30.7s) |   C |    40 | 14.0 |        
   28944 | 2021-06-27 15:31:17 |             MASTER- | (10h 17m 30.32s , +44d 22m 18.9s) |   C |    45 | 14.9 |        
   29003 | 2021-06-27 15:32:15 |             MASTER- | (10h 18m 57.96s , +42d 28m 45.1s) |   C |    45 | 14.5 |        
   29262 | 2021-06-27 15:36:32 |             MASTER- | (10h 04m 50.70s , +51d 20m 03.3s) |   C |    50 | 14.5 |        
   29334 | 2021-06-27 15:37:45 |             MASTER- | (09h 56m 05.11s , +44d 21m 52.9s) |   C |    50 | 15.3 |        
   29334 | 2021-06-27 15:37:45 |             MASTER- | (10h 06m 17.17s , +45d 39m 07.3s) |   C |    50 | 15.9 |        
   29397 | 2021-06-27 15:38:47 |             MASTER- | (10h 08m 04.64s , +43d 44m 11.9s) |   C |    50 | 13.9 |        
   29468 | 2021-06-27 15:39:58 |             MASTER- | (10h 16m 39.58s , +48d 09m 00.2s) |   C |    50 | 14.8 |        
   29468 | 2021-06-27 15:39:58 |             MASTER- | (10h 27m 53.40s , +49d 26m 06.9s) |   C |    50 | 14.6 |        
   29529 | 2021-06-27 15:40:59 |             MASTER- | (09h 47m 14.85s , +43d 42m 24.6s) |   C |    50 | 13.8 |        
   29604 | 2021-06-27 15:42:14 |             MASTER- | (09h 54m 38.42s , +46d 15m 13.5s) |   C |    50 | 14.6 |        
   29604 | 2021-06-27 15:42:14 |             MASTER- | (10h 05m 11.29s , +47d 32m 26.3s) |   C |    50 | 16.6 |        
   29676 | 2021-06-27 15:43:26 |             MASTER- | (09h 34m 41.92s , +44d 18m 27.6s) |   C |    50 | 13.8 |        
   29676 | 2021-06-27 15:43:26 |             MASTER- | (09h 44m 49.37s , +45d 35m 40.9s) |   C |    50 | 16.9 |        
   29739 | 2021-06-27 15:44:29 |             MASTER- | (09h 40m 37.37s , +40d 37m 56.3s) |   C |    50 | 16.2 |        
   29739 | 2021-06-27 15:44:29 |             MASTER- | (09h 50m 07.45s , +41d 55m 21.0s) |   C |    50 | 16.4 |        
   29810 | 2021-06-27 15:45:42 |             MASTER- | (09h 32m 24.62s , +46d 13m 13.9s) |   C |    45 | 17.7 |        
   29810 | 2021-06-27 15:45:42 |             MASTER- | (09h 42m 53.79s , +47d 30m 25.5s) |   C |    45 | 17.4 |        
   29873 | 2021-06-27 15:46:45 |             MASTER- | (10h 00m 42.61s , +40d 33m 37.8s) |   C |    45 | 18.1 |        
   29873 | 2021-06-27 15:46:45 |             MASTER- | (10h 10m 13.63s , +41d 50m 51.9s) |   C |    45 | 17.7 |        
   29944 | 2021-06-27 15:47:56 |             MASTER- | (09h 53m 45.96s , +48d 08m 22.2s) |   C |    45 | 17.9 |        
   29944 | 2021-06-27 15:47:56 |             MASTER- | (10h 04m 42.88s , +49d 25m 30.2s) |   C |    45 | 18.0 |        
   30000 | 2021-06-27 15:48:52 |             MASTER- | (09h 30m 39.06s , +48d 06m 02.4s) |   C |    45 | 17.4 |        
   30000 | 2021-06-27 15:48:52 |             MASTER- | (09h 41m 32.68s , +49d 23m 12.9s) |   C |    45 | 17.0 |        
   30069 | 2021-06-27 15:50:01 |             MASTER- | (10h 17m 39.78s , +44d 20m 32.3s) |   C |    45 | 17.1 |        
   30069 | 2021-06-27 15:50:01 |             MASTER- | (10h 27m 51.52s , +45d 37m 40.6s) |   C |    45 | 17.8 |        
   30130 | 2021-06-27 15:51:00 |             MASTER- | (10h 18m 58.77s , +42d 28m 12.6s) |   C |    50 | 12.3 |        
   30130 | 2021-06-27 15:51:00 |             MASTER- | (10h 28m 50.13s , +43d 45m 24.6s) |   C |    50 | 17.3 |        
   30205 | 2021-06-27 15:52:15 |             MASTER- | (10h 16m 51.62s , +46d 14m 32.9s) |   C |    50 | 17.2 |        
   30205 | 2021-06-27 15:52:15 |             MASTER- | (10h 27m 25.78s , +47d 31m 40.4s) |   C |    50 | 16.3 |        
   30285 | 2021-06-27 15:53:32 |             MASTER- | (09h 44m 15.48s , +39d 01m 44.7s) |   C |    55 | 17.3 |        
   30285 | 2021-06-27 15:53:32 |             MASTER- | (09h 53m 29.24s , +40d 19m 40.2s) |   C |    55 | 16.5 |        
   30354 | 2021-06-27 15:54:41 |             MASTER- | (10h 03m 48.49s , +38d 37m 40.5s) |   C |    55 | 17.6 |        
   30354 | 2021-06-27 15:54:41 |             MASTER- | (10h 13m 00.33s , +39d 55m 30.8s) |   C |    55 | 16.3 |        
   30432 | 2021-06-27 15:56:00 |             MASTER- | (09h 53m 23.46s , +50d 02m 19.7s) |   C |    55 | 16.1 |        
   30432 | 2021-06-27 15:56:00 |             MASTER- | (10h 04m 45.88s , +51d 20m 04.7s) |   C |    55 | 15.7 |        
   30509 | 2021-06-27 15:57:16 |             MASTER- | (09h 56m 14.00s , +44d 19m 18.1s) |   C |    55 | 17.9 |        
   30509 | 2021-06-27 15:57:16 |             MASTER- | (10h 06m 20.82s , +45d 37m 03.8s) |   C |    55 | 16.5 |        
   30576 | 2021-06-27 15:58:21 |             MASTER- | (09h 58m 06.03s , +43d 20m 01.9s) |   C |    60 | 16.9 |        
   30576 | 2021-06-27 15:58:21 |             MASTER- | (10h 08m 02.14s , +44d 37m 53.0s) |   C |    60 | 16.9 |        
   30661 | 2021-06-27 15:59:48 |             MASTER- | (10h 16m 49.25s , +48d 07m 27.6s) |   C |    55 | 17.9 |        
   30661 | 2021-06-27 15:59:48 |             MASTER- | (10h 27m 46.28s , +49d 25m 08.8s) |   C |    55 | 17.5 |        
   30730 | 2021-06-27 16:00:57 |             MASTER- | (09h 37m 28.35s , +42d 24m 40.7s) |   C |    55 | 17.0 |        
   30730 | 2021-06-27 16:00:57 |             MASTER- | (09h 47m 11.82s , +43d 42m 26.9s) |   C |    55 | 16.8 |        
   30819 | 2021-06-27 16:02:24 |             MASTER- | (09h 54m 42.62s , +46d 12m 13.3s) |   C |    60 | 17.3 |        
   30819 | 2021-06-27 16:02:24 |             MASTER- | (10h 05m 10.12s , +47d 29m 55.0s) |   C |    60 | 15.0 |        
   30902 | 2021-06-27 16:03:47 |             MASTER- | (09h 34m 49.11s , +44d 18m 31.9s) |   C |    60 | 17.9 |        
   30902 | 2021-06-27 16:03:47 |             MASTER- | (09h 44m 52.23s , +45d 36m 14.9s) |   C |    60 | 17.3 |        
   30969 | 2021-06-27 16:04:57 |             MASTER- | (09h 40m 19.67s , +43d 54m 24.8s) |   C |    55 | 17.6 |        
   30969 | 2021-06-27 16:04:57 |             MASTER- | (09h 50m 18.84s , +45d 12m 13.4s) |   C |    55 | 17.2 |        
   31047 | 2021-06-27 16:06:14 |             MASTER- | (09h 32m 29.57s , +46d 12m 40.9s) |   C |    55 | 17.9 |        
   31047 | 2021-06-27 16:06:14 |             MASTER- | (09h 42m 54.50s , +47d 30m 22.0s) |   C |    55 | 17.4 |        
   31129 | 2021-06-27 16:07:36 |             MASTER- | (10h 00m 39.50s , +43d 03m 28.8s) |   C |    55 | 17.7 |        
   31129 | 2021-06-27 16:07:36 |             MASTER- | (10h 10m 31.21s , +44d 21m 14.7s) |   C |    55 | 18.0 |        
   31197 | 2021-06-27 16:08:45 |             MASTER- | (09h 53m 45.48s , +48d 05m 44.4s) |   C |    55 | 17.9 |        
   31197 | 2021-06-27 16:08:45 |             MASTER- | (10h 04m 36.83s , +49d 23m 22.5s) |   C |    55 | 17.5 |        
   31274 | 2021-06-27 16:10:01 |             MASTER- | (09h 30m 51.08s , +48d 04m 41.0s) |   C |    55 | 18.0 |        
   31274 | 2021-06-27 16:10:01 |             MASTER- | (09h 41m 39.87s , +49d 22m 19.9s) |   C |    55 | 17.6 |        
   31354 | 2021-06-27 16:11:21 |             MASTER- | (10h 17m 40.58s , +44d 20m 28.4s) |   C |    55 | 18.4 |        
   31354 | 2021-06-27 16:11:21 |             MASTER- | (10h 27m 47.59s , +45d 38m 07.3s) |   C |    55 | 18.0 |        
   31421 | 2021-06-27 16:12:28 |             MASTER- | (10h 18m 59.84s , +42d 58m 04.5s) |   C |    55 | 17.3 |        
   31421 | 2021-06-27 16:12:28 |             MASTER- | (10h 28m 52.14s , +44d 15m 49.9s) |   C |    55 | 17.3 |        
   31505 | 2021-06-27 16:13:50 |             MASTER- | (10h 16m 59.01s , +46d 14m 26.1s) |   C |    60 | 18.4 |        
   31505 | 2021-06-27 16:13:50 |             MASTER- | (10h 27m 28.16s , +47d 32m 04.2s) |   C |    60 | 17.5 |        
   31587 | 2021-06-27 16:15:12 |             MASTER- | (09h 43m 50.24s , +43d 50m 05.3s) |   C |    60 | 16.6 |        
   31587 | 2021-06-27 16:15:12 |             MASTER- | (09h 53m 48.25s , +45d 07m 56.9s) |   C |    60 | 16.0 |        
   33913 | 2021-06-27 16:53:59 |             MASTER- | (10h 05m 22.58s , +51d 16m 29.5s) |   C |    60 | 17.0 |        
   33913 | 2021-06-27 16:53:59 |             MASTER- | (09h 53m 39.52s , +49d 59m 36.6s) |   C |    60 | 17.0 |        
   33994 | 2021-06-27 16:55:20 |             MASTER- | (10h 16m 41.76s , +49d 46m 04.9s) |   C |    60 | 17.7 |        
   33994 | 2021-06-27 16:55:20 |             MASTER- | (10h 28m 23.88s , +51d 03m 00.3s) |   C |    60 | 18.0 |        
   34051 | 2021-06-27 16:56:36 |             MASTER- | (09h 41m 22.92s , +51d 14m 09.2s) |   C |    20 | 17.1 |        
   34051 | 2021-06-27 16:56:36 |             MASTER- | (09h 29m 46.00s , +49d 56m 18.4s) |   C |    20 | 17.4 |        
   34095 | 2021-06-27 16:57:20 |             MASTER- | (10h 17m 33.94s , +49d 59m 43.6s) |   C |    20 | 17.7 |        
   34095 | 2021-06-27 16:57:20 |             MASTER- | (10h 29m 17.47s , +51d 17m 32.9s) |   C |    20 | 17.1 |        
   34126 | 2021-06-27 16:57:51 |             MASTER- | (10h 06m 15.72s , +53d 09m 16.6s) |   C |    20 | 17.1 |        
   34126 | 2021-06-27 16:57:51 |             MASTER- | (09h 54m 03.44s , +51d 51m 31.4s) |   C |    20 | 17.5 |        
   34330 | 2021-06-27 17:01:16 |             MASTER- | (10h 49m 55.35s , +47d 41m 02.4s) |   C |    20 | 17.1 |        
   34330 | 2021-06-27 17:01:16 |             MASTER- | (10h 39m 16.57s , +46d 23m 05.8s) |   C |    20 | 17.3 |        
   34362 | 2021-06-27 17:01:47 |             MASTER- | (10h 31m 03.06s , +53d 10m 56.9s) |   C |    20 | 15.6 |        
   34362 | 2021-06-27 17:01:47 |             MASTER- | (10h 19m 04.04s , +51d 53m 07.1s) |   C |    20 | 16.6 |        
   34394 | 2021-06-27 17:02:19 |             MASTER- | (10h 49m 44.61s , +43d 40m 57.2s) |   C |    20 | 17.0 |        
   34394 | 2021-06-27 17:02:19 |             MASTER- | (10h 39m 56.90s , +42d 22m 55.7s) |   C |    20 | 17.6 |        
   34426 | 2021-06-27 17:02:51 |             MASTER- | (10h 51m 03.09s , +49d 23m 10.6s) |   C |    20 | 16.5 |        
   34426 | 2021-06-27 17:02:51 |             MASTER- | (10h 40m 07.06s , +48d 05m 16.3s) |   C |    20 | 16.7 |        
   34470 | 2021-06-27 17:03:36 |             MASTER- | (09h 55m 07.00s , +53d 46m 55.0s) |   C |    20 | 16.4 |        
   34470 | 2021-06-27 17:03:36 |             MASTER- | (10h 07m 31.69s , +55d 04m 45.3s) |   C |    20 | 16.0 |        
   34501 | 2021-06-27 17:04:06 |             MASTER- | (09h 41m 23.84s , +55d 01m 36.9s) |   C |    20 | 16.4 |        
   34501 | 2021-06-27 17:04:06 |             MASTER- | (09h 29m 03.00s , +53d 43m 48.9s) |   C |    20 | 17.1 |        
   34533 | 2021-06-27 17:04:38 |             MASTER- | (09h 15m 57.59s , +53d 07m 35.3s) |   C |    20 | 16.6 |        
   34533 | 2021-06-27 17:04:38 |             MASTER- | (09h 04m 16.17s , +51d 49m 34.3s) |   C |    20 | 16.6 |        
   34581 | 2021-06-27 17:05:27 |             MASTER- | (10h 41m 34.47s , +49d 59m 32.7s) |   C |    20 | 16.6 |        
   34581 | 2021-06-27 17:05:27 |             MASTER- | (10h 52m 56.01s , +51d 17m 35.1s) |   C |    20 | 15.0 |        
   34614 | 2021-06-27 17:05:39 |         MASTER-SAAO | (10h 06m 44.41s , +37d 24m 14.8s) |   C |    60 | 17.6 |        
   34612 | 2021-06-27 17:05:57 |             MASTER- | (10h 33m 37.20s , +55d 05m 34.0s) |   C |    20 | 13.8 |        
   34612 | 2021-06-27 17:05:57 |             MASTER- | (10h 21m 11.80s , +53d 47m 38.3s) |   C |    20 | 14.7 |        
   34643 | 2021-06-27 17:06:28 |             MASTER- | (09h 57m 02.54s , +55d 39m 28.2s) |   C |    20 | 16.5 |        
   34676 | 2021-06-27 17:07:01 |             MASTER- | (09h 15m 17.18s , +54d 59m 44.6s) |   C |    20 | 15.8 |        
   34676 | 2021-06-27 17:07:01 |             MASTER- | (09h 02m 58.08s , +53d 41m 49.2s) |   C |    20 | 16.4 |        
   34711 | 2021-06-27 17:07:16 |         MASTER-SAAO | (10h 16m 40.91s , +37d 23m 07.3s) |   C |    60 | 17.6 |        
   34710 | 2021-06-27 17:07:35 |             MASTER- | (10h 44m 03.90s , +51d 52m 39.0s) |   C |    20 | 12.9 |        
   34746 | 2021-06-27 17:08:11 |             MASTER- | (09h 29m 39.46s , +55d 38m 42.3s) |   C |    20 | 16.0 |        
   34746 | 2021-06-27 17:08:11 |             MASTER- | (09h 42m 41.91s , +56d 56m 34.6s) |   C |    20 | 14.8 |        
   34780 | 2021-06-27 17:08:45 |             MASTER- | (11h 00m 48.78s , +44d 17m 13.9s) |   C |    20 | 14.9 |        
   34832 | 2021-06-27 17:09:17 |         MASTER-SAAO | (10h 22m 45.64s , +39d 18m 54.7s) |   C |    60 | 17.6 |        
   34822 | 2021-06-27 17:09:27 |             MASTER- | (11h 01m 36.55s , +46d 13m 10.3s) |   C |    20 | 12.9 |        
   34857 | 2021-06-27 17:10:02 |             MASTER- | (11h 00m 46.67s , +42d 24m 05.4s) |   C |    20 | 16.0 |        
   34916 | 2021-06-27 17:10:41 |         MASTER-SAAO | (10h 33m 04.24s , +39d 17m 15.0s) |   C |    60 | 17.5 |        
   34971 | 2021-06-27 17:11:56 |             MASTER- | (09h 40m 59.30s , +51d 12m 54.0s) |   C |    20 | 16.4 |        
   34971 | 2021-06-27 17:11:56 |             MASTER- | (09h 29m 47.69s , +49d 54m 45.1s) |   C |    20 | 17.0 |        
   35003 | 2021-06-27 17:12:28 |             MASTER- | (10h 17m 45.16s , +49d 57m 16.8s) |   C |    20 | 13.5 |        
   35040 | 2021-06-27 17:12:45 |         MASTER-SAAO | (09h 52m 06.09s , +35d 30m 51.0s) |   C |    60 | 15.9 |        
   35034 | 2021-06-27 17:12:59 |             MASTER- | (09h 54m 07.05s , +51d 51m 43.1s) |   C |    20 | 14.6 |        
   35075 | 2021-06-27 17:13:40 |             MASTER- | (09h 29m 11.24s , +51d 48m 52.4s) |   C |    20 | 15.5 |        
   35075 | 2021-06-27 17:13:41 |             MASTER- | (09h 40m 53.08s , +53d 06m 59.4s) |   C |    20 | 12.3 |        
   35158 | 2021-06-27 17:14:43 |         MASTER-SAAO | (10h 01m 50.59s , +35d 31m 43.0s) |   C |    60 | 17.0 |        
   35143 | 2021-06-27 17:14:48 |             MASTER- | (10h 49m 24.08s , +45d 35m 03.0s) |   C |    20 | 14.7 |        
   35143 | 2021-06-27 17:14:48 |             MASTER- | (10h 39m 20.29s , +44d 16m 54.0s) |   C |    20 | 14.8 |        
   35267 | 2021-06-27 17:16:32 |         MASTER-SAAO | (10h 25m 43.54s , +37d 23m 18.7s) |   C |    60 | 17.5 |        
   35380 | 2021-06-27 17:18:25 |         MASTER-SAAO | (10h 35m 51.09s , +37d 23m 18.8s) |   C |    60 | 17.8 |        
   35475 | 2021-06-27 17:20:00 |         MASTER-SAAO | (10h 10m 43.61s , +35d 29m 47.4s) |   C |    60 | 17.4 |        
   35568 | 2021-06-27 17:21:33 |         MASTER-SAAO | (10h 20m 34.10s , +35d 31m 14.3s) |   C |    60 | 17.7 |        
   35683 | 2021-06-27 17:23:29 |         MASTER-SAAO | (10h 42m 18.60s , +39d 17m 14.6s) |   C |    60 | 17.7 |        
   35783 | 2021-06-27 17:25:08 |         MASTER-SAAO | (10h 52m 43.74s , +39d 17m 13.2s) |   C |    60 | 18.0 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB210627B
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30332
SUBJECT: GRB 210627B: Fermi GBM Final Real-time Localization
DATE:    21/06/27 18:07:45 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 17:57:20 UT on 27 Jun 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210627B (trigger 646509445.742424 / 210627748).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 234.8, Dec = -6.0 (J2000 degrees, equivalent to J2000 15h 39m, -6d 00'), with a statistical uncertainty of 2.1 degrees.

The angle from the Fermi LAT boresight is 48.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210627748/quicklook/glg_skymap_all_bn210627748.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210627748/quicklook/glg_healpix_all_bn210627748.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210627748/quicklook/glg_lc_medres34_bn210627748.gif


GRB_name: GRB210627B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30333
SUBJECT: GRB 210627B: BALROG localization (Fermi Trigger  646509445/ GRB 210627748)
DATE:    21/06/27 19:37:43 GMT
FROM:    Jochen Greiner at MPE,Garching  <jcg@mpe.mpg.de>

B. Biltzinger, F. Kunzweiler, F. Berlato, J. Burgess & J. Greiner (all MPE Garching) report:

The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger 646509445
 at 17:57:20 on 27 June 2021 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) = 230.5+/-2.5 deg
Decl.(2000.0) = -5.9+/-1.5 deg
We estimate an additional systematic error of 2 deg.

Further details are available at:
https://grb.mpe.mpg.de/grb/GRB210627748/

The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB210627748/healpix

The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB210627748/json

                        


GRB_name: GRB210627B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30334
SUBJECT: Fermi GRB 210627B: Global MASTER-Net observations report 
DATE:    21/06/27 20:45:45 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

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

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

D. Buckley 
(South African Astronomical Observatory),

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

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

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




MASTER-SAAO robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 210627B ( Fermi GBM team, GCN 30332) errorbox  126 sec after notice time and 172 sec after trigger time at 2021-06-27 18:00:12 UT, with upper limit up to  18.9 mag. The observations began at zenith distance = 39 deg. The sun  altitude  is -28.1 deg. 

The galactic latitude b = 37 deg., longitude l =  0 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1646449

We obtain a following upper limits.  

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

     187 | 2021-06-27 18:00:12 |         MASTER-SAAO | (15h 39m 24.65s , -03d 56m 42.7s) |   C |    30 | 17.7 |        
     242 | 2021-06-27 18:00:12 |         MASTER-SAAO | (15h 39m 24.64s , -03d 56m 42.7s) |   C |   140 | 18.9 |  Coadd 
     275 | 2021-06-27 18:01:31 |         MASTER-SAAO | (15h 39m 30.47s , -03d 56m 21.7s) |   C |    50 | 18.2 |        
     350 | 2021-06-27 18:02:40 |         MASTER-SAAO | (15h 39m 26.91s , -03d 54m 57.7s) |   C |    60 | 18.3 |        
     581 | 2021-06-27 18:06:31 |         MASTER-SAAO | (15h 33m 03.26s , -08d 21m 15.4s) |   C |    60 | 18.5 |        
     733 | 2021-06-27 18:08:28 |         MASTER-SAAO | (15h 39m 22.87s , -06d 00m 02.8s) |   C |   130 | 18.8 |        
     929 | 2021-06-27 18:11:25 |         MASTER-SAAO | (15h 39m 22.95s , -06d 01m 59.2s) |   C |   170 | 18.7 |        
    1160 | 2021-06-27 18:15:10 |         MASTER-SAAO | (15h 39m 26.92s , -06d 00m 21.0s) |   C |   180 | 18.8 |        
    1396 | 2021-06-27 18:19:07 |         MASTER-SAAO | (15h 39m 20.47s , -06d 00m 57.4s) |   C |   180 | 18.6 |        
    1575 | 2021-06-27 18:23:06 |         MASTER-SAAO | (15h 41m 02.44s , -08d 19m 46.4s) |   C |    60 | 18.0 |        
    2477 | 2021-06-27 18:38:07 |         MASTER-SAAO | (15h 33m 04.67s , -08d 20m 57.5s) |   C |    60 | 17.2 |        
    2596 | 2021-06-27 18:40:06 |         MASTER-SAAO | (15h 41m 04.35s , -08d 19m 36.6s) |   C |    60 | 17.3 |        
    2715 | 2021-06-27 18:42:05 |         MASTER-SAAO | (15h 29m 10.60s , -06d 25m 24.4s) |   C |    60 | 17.4 |        
    2834 | 2021-06-27 18:44:04 |         MASTER-SAAO | (15h 37m 05.80s , -06d 26m 24.8s) |   C |    60 | 17.3 |        
    3783 | 2021-06-27 18:59:54 |         MASTER-SAAO | (15h 33m 14.17s , -08d 19m 07.2s) |   C |    60 | 14.6 |        
    3908 | 2021-06-27 19:01:58 |         MASTER-SAAO | (15h 41m 15.95s , -08d 20m 58.8s) |   C |    60 | 14.3 |        
    4027 | 2021-06-27 19:03:58 |         MASTER-SAAO | (15h 29m 24.66s , -06d 25m 14.9s) |   C |    60 | 14.4 |        
    4145 | 2021-06-27 19:05:56 |         MASTER-SAAO | (15h 37m 16.64s , -06d 26m 08.9s) |   C |    60 | 14.7 |        
    4230 | 2021-06-27 19:07:20 |         MASTER-SAAO | (15h 41m 37.93s , -04d 32m 18.1s) |   C |    60 | 15.5 |        
    4348 | 2021-06-27 19:09:19 |         MASTER-SAAO | (15h 49m 29.63s , -04d 33m 34.3s) |   C |    60 | 14.5 |        
    4467 | 2021-06-27 19:11:18 |         MASTER-SAAO | (15h 44m 33.54s , -06d 25m 32.0s) |   C |    60 | 14.7 |        
    4586 | 2021-06-27 19:13:16 |         MASTER-SAAO | (15h 52m 33.05s , -06d 27m 34.6s) |   C |    60 | 14.1 |        
    4698 | 2021-06-27 19:15:09 |         MASTER-SAAO | (15h 26m 31.74s , -04d 31m 38.4s) |   C |    60 | 14.9 |        
    4812 | 2021-06-27 19:17:03 |         MASTER-SAAO | (15h 34m 28.95s , -04d 30m 54.4s) |   C |    60 | 14.8 |        
    4931 | 2021-06-27 19:19:01 |         MASTER-SAAO | (15h 29m 32.62s , -06d 25m 41.1s) |   C |    60 | 14.8 |        
    5050 | 2021-06-27 19:21:00 |         MASTER-SAAO | (15h 37m 25.99s , -06d 26m 57.7s) |   C |    60 | 14.8 |        
    5168 | 2021-06-27 19:22:59 |         MASTER-SAAO | (15h 41m 46.92s , -04d 33m 02.7s) |   C |    60 | 14.4 |        
    5287 | 2021-06-27 19:24:57 |         MASTER-SAAO | (15h 49m 42.07s , -04d 31m 27.4s) |   C |    60 | 14.6 |        
    5406 | 2021-06-27 19:26:56 |         MASTER-SAAO | (15h 44m 43.29s , -06d 26m 47.4s) |   C |    60 | 14.8 |        
    5877 | 2021-06-27 19:34:47 |         MASTER-SAAO | (15h 52m 47.68s , -06d 25m 16.9s) |   C |    60 | 12.8 |        
    6890 | 2021-06-27 19:50:40 |         MASTER-SAAO | (15h 22m 52.22s , -05d 53m 52.7s) |   C |   180 | 14.8 |        
    7262 | 2021-06-27 19:57:52 |         MASTER-SAAO | (15h 44m 57.88s , -06d 25m 27.2s) |   C |    60 | 12.7 |        
    7360 | 2021-06-27 19:59:30 |         MASTER-SAAO | (15h 52m 56.65s , -06d 24m 44.3s) |   C |    60 | 14.3 |        
    7480 | 2021-06-27 20:01:30 |         MASTER-SAAO | (15h 27m 02.62s , -04d 30m 58.8s) |   C |    60 | 15.2 |        
    7572 | 2021-06-27 20:03:02 |         MASTER-SAAO | (15h 34m 54.37s , -04d 32m 06.9s) |   C |    60 | 14.4 |        
    8194 | 2021-06-27 20:13:24 |         MASTER-SAAO | (15h 26m 42.01s , -08d 19m 28.4s) |   C |    60 | 14.1 |        
    8716 | 2021-06-27 20:22:07 |         MASTER-SAAO | (15h 32m 18.44s , -02d 35m 57.6s) |   C |    60 | 12.8 |        
    9374 | 2021-06-27 20:33:05 |         MASTER-SAAO | (15h 25m 50.78s , -08d 17m 14.7s) |   C |    60 | 14.4 |        
    9756 | 2021-06-27 20:39:26 |         MASTER-SAAO | (15h 32m 23.04s , -02d 36m 06.7s) |   C |    60 | 13.5 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB210626A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30336
SUBJECT: GRB 210626A: GIT optical upper limit
DATE:    21/06/28 08:53:15 GMT
FROM:    Harsh Kumar at Indian Inst of Tech,Bombay  <harshkosli13@gmail.com>

H. Kumar(IITB), J. Stanzin (IAO), V. Bhalerao(IITB), G. C. Anupama(IIA), S.
Barway(IIA) report on behalf of the GIT team:

We observed GRB 210626A detected by Fermi GBM (GCN #30323) with 0.7 m
GROWTH-India Telescope (GIT). The GRB was also detected by Swift/BAT-GUANO (GCN
#30325) and later on, Swift-XRT detected X-ray afterglow candidate (GCN
#30329). We obtained exposures in the r' filter. We did not detect any new
source in our stacked image within the 5.7 arcsec circle, around RA:
14:46:05.83, Dec: -01:09:22.5 (GCN #30329). Further, we did not find any
new source within the 5 arcmin region identified by BAT localisation
(GCN #30325).
The obtained upper limit follow as:

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

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

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

 2459392.2353 | 9.37 | 2 x 300 (stacked) | r' | > 20.5 |

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

The magnitudes are calibrated against PanSTARRS (Flewelling et al., 2018)
and not corrected for Galactic extinction.

The GROWTH India Telescope (GIT) is a 70-cm telescope with a 0.7-degree
field of view, set up by the Indian Institute of Astrophysics and the
Indian Institute of Technology Bombay with support from the Indo-US Science
and Technology Forum (IUSSTF) and the Science and Engineering Research
Board (SERB) of the Department of Science and Technology (DST), Government
of India (https://sites.google.com/view/growthindia/). It is located at the
Indian Astronomical Observatory (Hanle), operated by the Indian Institute
of Astrophysics (IIA).


GRB_name: GRB210626A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30337
SUBJECT: GRB 210626A: Ondrejov D50 optical limit
DATE:    21/06/28 09:59:16 GMT
FROM:    Martin Jelinek at Astro.Inst-AVCR,Ondrejov  <martin.jelinek@asu.cas.cz>

Martin Jelinek, Jan Strobl, Rene Hudec and Cyril Polasek (ASU CAS Ondrejov,
CZ), report:

We observed the Swift-improved localization (Tohuvavohu et al. GCN 30325,
Perri et al. GCN 30329) of the GBM-detected GRB 210626A (Fermi GBM Team,
GCN 30323) with the 50 cm robotic telescope (D50) of Ondrejov observatory
in Czech Republic. We obtained a set of 120 s Sloan-i' exposures starting
at 21:10 UT, i.e.  0.5386 d after the initial trigger.

The magnitude limit of our 34 x 120 s image with a mean time T-T0 0.5626 d
post burst is i' > 21.2 (AB). The XRT (Perri et al. GCN 30329) error box
does not appear completely clean in the image, there is a noise fluctuation
or possibly a candidate at the level of i' = 21.3 +/- 0.4. While we mention
this, we also note that this is in a light halo of a nearby bright star, so
artefacts of this kind may not be excluded.


GRB_name: GRB210619B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30338
SUBJECT: GRB 210619B: Deep CAHA 2.2m detection and late-time light curve behavior
DATE:    21/06/28 10:29:27 GMT
FROM:    Alexander Kann at IAA-CSIC  <kann@iaa.es>

D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC, 
DARK/NBI), M. Jelinek (ASU CAS Ondrejov), M. Blazek, C. Thoene, J. F. 
Agui Fernandez (all HETH/IAA-CSIC), and P. Minguez (CAHA) report:

We re-observed the afterglow of GRB 210619B (D'Avanzo et al., GCN 
#30261) with CAFOS mounted at the 2.2m Calar Alto telescope (Almeria, 
Spain). Image depth was influenced by moonlight but conditions were 
good. We obtained 20 x 180 s images in r'.

The afterglow is faintly detected in the stacked image. Against 
Pan-STARRS comparison stars, we derive r' = 22.56 +/- 0.16 mag at 
6.12346 d after the trigger.

Using selected data from GCN Circulars (Jelinek et al., GCN #30263, 
#30281; Pellegrin et al., GCN #30268; Perley, GCN #30271; Zheng & 
Filippenko, GCN #30273; Blazek et al., GCN #30274; Kann et al., GCN 
#30275; Xin et al., GCN #30277; D'Avanzo et al., GCN #30288; Moskvitin & 
Maslennikova, GCNs #303291, #30303, #30309; Romanov, GCN #30292; Hu et 
al., GCN #30293; Zhu et al., GCN #30294; Belkin et al., GCN #30299; 
Romanov & Lane, GCN #30305; Vinko et al., GCN #30320), we find the 
afterglow after 0.057 d can be fit by a smoothly broken power-law with a 
sharp break and parameters alpha_1 = 0.742 +/- 0.013, alpha_2 = 1.221 
+/- 0.045, and break time t_b = 0.465 +/- 0.048 d (40136 +/- 4108 s).

This fully confirms the steepening decay reported by Jelinek et al., GCN 
#30281; Kumar et al., GCN #30286.

Note that the best fit of the X-ray light curve at the time finds 
alpha_1 = 0.978 +0.012 -0.019, alpha_2 = 1.50 +/- 0.035, t_b = 0.152 
+0.015 -0.024 d (13100 +1300 -2100 s). However, the early decay (alpha_0 
= 0.773 +0.087 -0.141, up to 500 s) is very similar to the optical decay 
we find from ~5000 s onward to the (optical) break. We note that the 
post-break decay slope would be extremely shallow if this were actually 
a jet break, but no deviation from this decay is seen until ~6 d.


GRB_name: GRB210626A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30339
SUBJECT: GRB 210626A: CAHA 2.2m telescope optical limit
DATE:    21/06/28 10:43:38 GMT
FROM:    Youdong HU at IAA-CSIC  <huyoudong072@hotmail.com>

Y.-D. Hu, T.-R. Sun, E. Fernandez-Garcia, A. J. Castro-Tirado, M. D. Caballero-Garcia, M. A. Castro Tirado (IAA-CSIC), A. Fernandez and I. Hermelo (CAHA) on behalf of a larger collaboration, report:

Following the detection of GRB 210626A by both Swift (Tohuvavohu et al. GCNC 30325) and Fermi (Fermi/GBM team GCNC 30323), we triggered the 2.2m CAHA telescope (+ CAFOS) at the Calar Alto Observatory (Almeria, Spain), gathering images starting on June 27, 20:37 UT (i.e. 1.5 day post trigger). On the co-added image (i-band, 3x180s), no optical transient down to 22.4 mag is detected at the X-ray afterglow candidate position reported by Swift/XRT (Evans et al. GCNC 30326, Perri et al. GCNC 30329).

We thank the staff at Calar Alto observatory for their excellent support.


GRB_name: GRB210626A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30340
SUBJECT: GRB 210626A: Fermi GBM observation
DATE:    21/06/28 15:25:08 GMT
FROM:    Andreas von Kienlin at MPE  <azk@mpe.mpg.de>

A. von Kienlin (MPE) and C. Meegan (UAH) 
report on behalf of the Fermi GBM Team:

"At 08:16:15.99 UT on 26 June 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210626A (trigger 646388180 / 210626345), which was
also 
detected by the Swift/BAT-GUANO (Tohuvavohu et al. 2021, GCN 30325).
The Fermi GBM Final Real-time Localization is consistent with the Swift
position.

The angle from the Fermi LAT boresight at the GBM trigger time is 73
degrees.

The GBM light curve shows a singel pulse with a duration (T90) of 
about 34 s (50-300 keV). The time-averaged spectrum from T0-5.632 s 
to T0+29.184 s is best fit by a Band function with Epeak= 86 +/- 18 keV, 
alpha = -1.21 +/- 0.16 and beta = -2.25 +/- 0.24

The event fluence (10-1000 keV) in this time interval is
(5.1 +/- 0.4)E-06 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0+5.696 s in the 10-1000 keV band
is 3.40 +/- 0.24 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: GRB210626A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30341
SUBJECT: GRB 210626A: Swift/XRT afterglow confirmation
DATE:    21/06/28 19:07:34 GMT
FROM:    Antonino D'Ai at IASF-PA  <antonino.dai@inaf.it>

Antonino D'AÃ¬ (INAF-IASFPA) & Aaron Tohuvavohu (Uni. Toronto) 
report on behalf of the Swift-XRT team:

Swift-XRT has performed further follow-up observations of the
Fermi/GBM (von Kienlin GCN 30340) and Swift/BAT-GUANO detected burst 
GRB 210626A (Tohuvavohu et al., GCN Circ. 30325), collecting 7.9 ks 
of Photon Counting (PC) mode data between T0+29.7 ks and T0+143 ks.

The X-ray source detected in the first 1.4 ks of data as possible 
GRB afterglow candidate  (Perri et al. GCN 30329)  has faded more 
than 3 sigma in the  latest observation, and it is thus confirmed as the 
X-ray afterglow of the burst.

The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/xrt_curves/00021453/.

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


GRB_name: GRB210619B
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30343
SUBJECT: GRB 210619B: Sayan observatory 1.6-m telescope observations
DATE:    21/06/29 20:14:37 GMT
FROM:    Rodion Burenin at IKI, Moscow  <rodion@hea.iki.rssi.ru>

I. Zaznobin, R. Burenin, A. Lutovinov (IKI),
E. Klunko, M. Eselevich (ISTP SB RAS)

report:

The field of GRB 210619B detected by Swift (D'Avanzo et al. GCN
30261), GECAM (Zhao et al. GCN 30264), CALET (Kawakubo et al. GCNC
30284), SRG/ART-XC (Levin et al. GCNC 30283), Fermi-LAT (Axelsson et
al. GCNC 30270), Konus-Wind (Svinkin et al. GCN 30276) and Fermi/GBM
(Poolakkil et al. GCNC 30279) was observed with the Sayan observatory
1.6-m telescope AZT-33IK, using a CCD photometer, starting at
2021/06/20 17:58 UT, i.e. approximately 18 hours after the burst.

We obtained 12x60 s images in each g,r,i,z SDSS filter. The OT is
clearly detected in every frame, with the following magnitudes:

g = 20.26 +- 0.06
r = 19.51 +- 0.08
i = 19.08 +- 0.06
z = 18.69 +- 0.07


GRB_name: GRB210627B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30345
SUBJECT: GRB 210627B: GECAM detection
DATE:    21/06/30 04:07:22 GMT
FROM:    Wangchen Xue at IHEP  <xuewc@ihep.ac.cn>

W. C. Xue, S. L. Xiong, X. Y. Song, Y. Huang, S. L. Xie, S. Xiao, C. Cai,
J. C. Liu, C. Y. Li, Y. Q. Zhang,  Y. Zhao, Z. W. Guo, X. Y. Zhao, C. Zheng,
Z. H. An, C. Chen, G. Chen, W. Chen, M. Gao, K. Gong, D. Y. Guo, J. J. He,
B. Li, C. Li, J. H. Li, Q. X. Li, X. B. Li, X. Q. Li, Y. G. Li, X. H. Liang,
J. Y. Liao, J. C. Liu, X. J. Liu, Y. Q. Liu, F. J. Lu, Q. Luo, X. Ma,
G. Ou, W. X. Peng, R. Qiao, D. L. Shi, J. Y. Shi, L. M. Song,
G. X. Sun, X. L. Sun, Y. L. Tuo, C. W. Wang, J. Z. Wang,
P. Wang, X. Y. Wen, Y. B. Xu, Y. P. Xu, S. Yang, M. Yao, Q. B. Yi,
B. X. Zhang, C. Y. Zhang, D. L. Zhang, Fan Zhang, Fei Zhang, H. M. Zhang,
K. Zhang, P. Zhang, S. N. Zhang, Z. Zhang, S. Y. Zhao, S. J. Zheng,
X. Zhou (IHEP), report on behalf of GECAM team:

During the commissioning phase, GECAM-B was triggered in-flight by a long
burst, GRB 210627B, at 2021-06-27T17:57:21.550 UTC (denoted as T0), which was
also observed by Fermi/GBM (GCN #30332).

According to the GECAM-B light curves in about 20-500 keV, 
this burst mainly consists of multiple pulses with a duration of 14.33 s.

The GECAM light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/multiLCvsE_tn210627_175830.png

GECAM-B localized this burst to the following position (J2000):
Ra: 240.1 deg
Dec: 2.0 deg
Err: 5.3 deg (1-sigma, statistical only)
The current systematic error of location is estimated to be several degrees
which could be minimized by the ongoing calibration. This position is 
consistent with the Fermi GBM localization (GCN #30332 and #30333) within
the error.

The location map could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/tn210627_175830_locationSatB_map.png

Please note that all GECAM results here are preliminary. The final analysis
will be published in journal papers or GECAM online catalog.

Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor
(GECAM) mission consists of two small satellites (GECAM-A and GECAM-B) in
Low Earth Orbit (600 km, 29 deg), launched on Dec 10, 2020 (Beijing Time),
which was funded by the Chinese Academy of Sciences (CAS).


GRB_name: GRB210702A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30351
SUBJECT: GRB 210702A: Swift detection of a burst with a bright optical counterpart
DATE:    21/07/02 19:31:14 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), J. A. Kennea (PSU),
N. J. Klingler (GSFC/UMBC/CRESSTII), S. Laha (GSFC/UMBC/CRESST),
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester) and
D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 19:07:13 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 210702A (trigger=1058804).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 168.570, -36.741 which is 
   RA(J2000) = 11h 14m 17s
   Dec(J2000) = -36d 44' 28"
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 100 sec.  The peak count rate
was ~10,000 counts/sec (15-350 keV), at ~2 sec after the trigger. 

The XRT began observing the field at 19:08:49.2 UT, 95.5 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 168.5813, -36.7474 which is equivalent to:
   RA(J2000)  = 11h 14m 19.51s
   Dec(J2000) = -36d 44' 50.6"
with an uncertainty of 11.0 arcseconds (radius, 90% containment). No
event data are yet available to determine the column density using
X-ray spectroscopy. 

The initial flux in the 2.5 s image was 1.00e-08 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of  45 seconds with the U filter starting
315 seconds after the BAT trigger. There is a candidate afterglow in the
rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  = 11:14:18.83 = 168.57846
  DEC(J2000) = -36:44:48.8  = -36.74690
with a 90%-confidence error radius of about 0.61 arc sec. This position is 8.4
arc sec. from the center of the XRT error circle. The estimated magnitude is
11.72 with a 1-sigma error of about  0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.121. 

Burst Advocate for this burst is A. Y. Lien (amy.y.lien 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: GRB210702A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30353
SUBJECT: Swift GRB 210702A: Global MASTER-Net observations report 
DATE:    21/07/02 19:43:25 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

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

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

D. Buckley 
(South African Astronomical Observatory),

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

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

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




MASTER-SAAO robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB 210702A ( A. Y. Lien et al., GCN 30351) errorbox 822 sec after trigger time at 2021-07-02 19:20:56 UT, with upper limit up to  18.6 mag. The observations began at zenith distance = 51 deg. The sun  altitude  is -44.7 deg. 

The galactic latitude b = 22 deg., longitude l = 283 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1650622

We obtain a following upper limits.  

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

     903 |         MASTER-SAAO | P\  |   160 | 18.6 |        
    1084 |         MASTER-SAAO | P\  |   180 | 17.9 |        
    1284 |         MASTER-SAAO | P\  |   180 | 17.6 |        


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


GRB_name: GRB210702A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30354
SUBJECT: GRB210702A: MeerLICHT multi-colour photometry
DATE:    21/07/02 21:33:49 GMT
FROM:    Andrew Levan at U.of Leicester  <a.levan@astro.ru.nl>

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

Following the detection of GRB210702A by Swift and its optical
counterpart (Lien et al., GCN30351), the 0.6m MeerLICHT telescope,
located at Sutherland, South Africa obtained a series of 60s images in
the q,u,q,g,q,r,q,i,q,z,q,u,q,g,q bands, starting at 2021-07-02,
19:23:26.586 UT, 16 minutes after the Swift detection, and 3 minutes 
after the distribution of the BAT alert. 

The source identified by Swift UVOT is clearly detected as a new
transient at coordinates 

RA(ICRS) = 168.57839 =  11:14:18.81 (+/-0.06â€)
DEC(ICRS)= -36.74702 = -36:44:49.27 (+/- 0.04â€)

MeerLICHT astrometry is calibrated against Gaia DR2.

The first source detections are, at:
q = 12.815 +/- 0.001 +/- 0.018   (19:23:26 UT)
u = 13.585 +/- 0.004 +/- 0.041   (19:25:10 UT)
g = 13.394 +/- 0.002 +/- 0.021   (19:28:46 UT)
r = 13.193 +/- 0.002 +/- 0.015 (19:32:18 UT)
i = 13.096 +/- 0.003 +/- 0.034   (19:35:42 UT)   
z = 13.100 +/- 0.004 +/- 0.025   (19:39:25 UT)
where the first uncertainty on the magnitude is the statistical
uncertainty and the second is the uncertainty on the photometric
calibration.

Our repeated q-band observations show decay consistent with a power law
with exponent of approximately -1.2. 

Further data taking was suspended due to high winds. 

Reference images of the field show no underlying host galaxy down to
the 5-sigma limiting magnitude, at the position of the afterglow, at:
u > 19.54
g > 20.44
q > 21.23
r > 20.20
i > 19.72
z > 18.90

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: GRB210702A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30355
SUBJECT: GRB 210702A: Swift/UVOT redshift
DATE:    21/07/02 23:27:24 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N. P. M. Kuin (UCL-MSSL) reports on behalf of the Swift/UVOT team:

The Swift/UVOT obtained a 49s grism spectrum of GRB 210702A
starting 282 s after the BAT trigger (Lien et al., GCN Circ. 30351).
The spectrum shows a clear break at 2011 Angstrom, and absorption features
attributable to Ly-alpha and Ly-beta suggesting
a redshift of z=1.1757+/-0.0093. An possible intervening system is present
at
z=1.050 based on a weaker line seen at 2492A.

The wavelength anchor/zeropoint in the uv grism is uncertain by typically
15A, which translates to an uncertainty as quoted in the redshift above.


GRB_name: GRB210702A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30356
SUBJECT: GRB 210702A: preliminary Swift/UVOT photometry
DATE:    21/07/02 23:31:49 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N. P. M. Kuin (UCL-MSSL) and A. Y. Lien (GSFC/UMBC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210702A
104 s after the BAT trigger (Lien et al., GCN Circ. 30351).
A source consistent with the XRT position
(Lien et al. GCN Circ. 30351)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  11:14:18.70 = 168.57793 (deg.)
    Dec (J2000) = -36:44:50.0  = -36.74723 (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              104          254          147         15.70 +/- 0.02
b                 3516         3716          197         15.46 +/- 0.03
u                  316          361           44         11.37 +/- 0.05

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.121 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB210702A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30357
SUBJECT: GRB 210702A: VLT/X-shooter redshift
DATE:    21/07/03 03:58:49 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

D. Xu (NAOC), L. Izzo (DARK/NBI), A. de Ugarte Postigo (HETH/IAA-CSIC, 
DARK/NBI), D. A. Kann (HETH/IAA-CSIC), S. Y. Fu (NAOC), S. Campana 
(INAF-OAB), V. D'Elia (ASI/SSDC, INAF/OAR), A. J. Levan (Radboud U. 
Nijmegen), B. Milvang-Jensen (DAWN/NBI), D. A. Perley (LJMU), G. 
Pugliese (API, Univ. Amsterdam), R. L. C. Starling (Univ. Leicester), N. 
R. Tanvir (Univ. Leicester), S. Vergani (CNRS - Observatoire de 
Paris/GEPI), and K. Wiersema (Univ. Warwick) report on behalf of the 
Stargate Consortium:

We observed the bright afterglow (Lien et al., GCN #30351; Lipunov et 
al., GCN #30352; Groot et al., GCN #30354; Kuin et al., GCN #30356) of 
GRB 210702A (Lien et al., GCN #30351) using the ESO VLT UT3 (Melipal) 
equipped with the X-shooter spectrograph. Our spectra cover the 
wavelength range 3000-25000 AA, and consist of 4 exposures of 600 s 
each. The observation mid-time was 2021 July 2.997 UT (i.e., 4.80 hr 
after the GRB).

In a 20 s image taken with the acquisition camera on July 02.975 UT, we 
detect the optical afterglow at r' = 16.91 +/- 0.01 mag (AB system), 
measured against three SkyMapper field stars.

In our spectrum, strong continuum is detected over the whole observed 
range. We detect a plethora of metallic absorption features, among them 
Si II, Si II*, C IV, Fe II, Fe II*, Al II, Ni II, Ni II*, Al III, Zn II, 
Mg I, Cr II, Mn II, Mg II, Mg I, and Ca II, all at a common redshift of 
z = 1.160. This is about 1.5 sigma lower than, but is broadly consistent 
with the value reported by Swift/UVOT (Kuin et al., GCN #30355). No 
emission feature is present in the spectrum. The detection of excited 
transitions establishes this as the redshift of the GRB.

There is also an intervening system detected at z = 0.538 showing Mg II 
and Mg I absorption features.

We acknowledge excellent support from the observing staff at Paranal, in 
particular Alain Smette and Bin Yang.


GRB_name: GRB210702A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30358
SUBJECT: GRB 210702A: Swift-XRT refined Analysis
DATE:    21/07/03 08:49:45 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

V. D'Elia (SSDC & INAF-OAR), A. D'Ai (INAF-IASFPA), J. D. Gropp (PSU),
J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), J.P. Osborne (U.
Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A.
Melandri (INAF-OAB) and A.Y. Lien report on behalf of the Swift-XRT
team:

We have analysed 6.3 ks of XRT data for GRB 210702A (Lien et al. GCN
Circ. 30351), from 84 s to 38.4 ks after the  BAT trigger. The data
comprise 310 s in Windowed Timing (WT) mode (the first 9 s were taken
while Swift was slewing) with the remainder in Photon Counting (PC)
mode. Using 4559 s of PC mode data and 10 UVOT images, we find an
enhanced XRT position (using the XRT-UVOT alignment and matching UVOT
field sources to the USNO-B1 catalogue): RA, Dec = 168.57877, -36.74715
which is equivalent to:

RA (J2000): 11h 14m 18.91s
Dec(J2000): -36d 44' 49.7"

with an uncertainty of 1.9 arcsec (radius, 90% confidence).

The light curve can be modelled with an initial power-law decay with an
index of alpha=1.005 (+0.014, -0.013), followed by a break at T+7161 s
to an alpha of 1.68 (+0.11, -0.10).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.570 (+0.018, -0.015). The
best-fitting absorption column is  consistent with the Galactic value
of 1.2 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has
a photon index of 1.95 (+/-0.07) and a best-fitting absorption column
of 1.8 (+/-1.0) x 10^21 cm^-2. The counts to observed (unabsorbed)
0.3-10 keV flux conversion factor deduced from this spectrum  is 3.5 x
10^-11 (4.5 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Galactic foreground: 1.2 x 10^21 cm^-2
Intrinsic column:    1.8 (+/-1.0) x 10^21 cm^-2 at z=1.16
Photon index:      1.95 (+/-0.07)

If the light curve continues to decay with a power-law decay index of
1.68, the count rate at T+24 hours will be 0.044 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.6 x
10^-12 (2.0 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/01058804.

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


GRB_name: GRB210610A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30359
SUBJECT: GRB 210610A: JCMT SCUBA-2 sub-mm observations
DATE:    21/07/03 08:53:23 GMT
FROM:    Ian Smith at Rice U  <ian.smith.astronomy@gmail.com>

I.A. Smith (Rice U.), D.A. Perley (LJMU), and N.R. Tanvir 
(U. of Leicester) report:

We observed the Swift UVOT location of GRB 210610A (Page 
et al., GCN Circ. 30160) using the SCUBA-2 sub-millimeter 
continuum camera on the James Clerk Maxwell Telescope.  
Observations totaling 3.1 hours were obtained on UT 2021-06-11, 
2021-06-12, and 2021-06-13 in good weather conditions each day.
No counterpart was detected in the individual or combined maps.
Combining all the data, the RMS background noise was 0.91 mJy/beam 
at 850 microns and 6.2 mJy/beam at 450 microns; the mid-point of 
the run was 1.73 days after the burst trigger.  

We thank Patrice Smith, Alexis-Ann Acohido, Harriet Parsons, 
Mark Rawlings, and the JCMT staff for the prompt support of these 
observations that were taken under project M21AP020.


GRB_name: GRB210610B
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30360
SUBJECT: GRB 210610B: JCMT SCUBA-2 sub-mm observations
DATE:    21/07/03 08:56:12 GMT
FROM:    Ian Smith at Rice U  <ian.smith.astronomy@gmail.com>

I.A. Smith (Rice U.), D.A. Perley (LJMU), and N.R. Tanvir 
(U. of Leicester) report:

We observed the Swift UVOT location of GRB 210610B (Page 
et al., GCN Circ. 30170) using the SCUBA-2 sub-millimeter 
continuum camera on the James Clerk Maxwell Telescope.  
Observations totaling 3.1 hours were obtained on UT 2021-06-11, 
2021-06-12, and 2021-06-13 in good weather conditions each day.
No counterpart was detected in the individual or combined maps.
Combining all the data, the RMS background noise was 0.94 mJy/beam 
at 850 microns and 5.7 mJy/beam at 450 microns; the mid-point of 
the run was 1.61 days after the burst trigger.  

We thank Patrice Smith, Alexis-Ann Acohido, Harriet Parsons,
Mark Rawlings, and the JCMT staff for the prompt support of these 
observations that were taken under project M21AP020.


GRB_name: GRB210619B
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30361
SUBJECT: GRB 210619B: JCMT SCUBA-2 sub-mm observations
DATE:    21/07/03 08:59:09 GMT
FROM:    Ian Smith at Rice U  <ian.smith.astronomy@gmail.com>

I.A. Smith (Rice U.), D.A. Perley (LJMU), and N.R. Tanvir 
(U. of Leicester) report:

We observed the Swift UVOT location of GRB 210619B (D'Avanzo 
et al., GCN Circ. 30261) using the SCUBA-2 sub-millimeter 
continuum camera on the James Clerk Maxwell Telescope.  
Observations totaling 2.1 hours were obtained on UT 2021-06-20 and
2021-06-21 in average and poor weather conditions respectively.
No counterpart was detected in the individual or combined maps.
Combining all the data, the RMS background noise was 1.61 mJy/beam 
at 850 microns and 27.9 mJy/beam at 450 microns; the mid-point of 
the run was 1.07 days after the burst trigger.  

We thank Patrice Smith, Mark Rawlings, Harriet Parsons, and the 
JCMT staff for the prompt support of these observations that were 
taken under project M21AP020.


GRB_name: GRB210702A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30362
SUBJECT: GRB 210702A: CALET Gamma-Ray Burst Monitor detection
DATE:    21/07/03 09:28:11 GMT
FROM:    Valentin Pal'shin at AGU  <val@phys.aoyama.ac.jp>

K. Yamaoka (Nagoya U),
A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU),
Y. Kawakubo (LSU), S. Nakahira (RIKEN), Y. Asaoka (ICRR),
S. Torii, Y. Akaike, K. Kobayashi (Waseda U),
Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC),
M. L. Cherry (LSU), S. Ricciarini (U of Florence),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

The long bright GRB 210702A (Swift detection: Lien et al., GCN Circ. 30351;
https://gcn.gsfc.nasa.gov/other/210702A.gcn3) triggered the CALET
Gamma-ray Burst Monitor (CGBM) at 19:07:06.474 UTC on 2 July 2021
(http://cgbm.calet.jp/cgbm_trigger/flight/1309287819/index.html).
The burst signal was seen by all CGBM detectors.

The burst light curve shows a FRED-like pulse which starts at T+2.1 sec,
peaks at T+6.3 sec,and ends at T+51.3 sec. The T90 and T50 durations
measured by the SGM data are 32.1 +- 4.6 sec and 9.2 +- 0.9 sec
(40-1000 keV), respectively.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1309287819/

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


GRB_name: GRB210702A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30363
SUBJECT: GRB 210702A: AGILE detection
DATE:    21/07/03 10:43:45 GMT
FROM:    Alessandro Ursi at INAF/IAPS  <alessandro.ursi@gmail.com>

A. Ursi (INAF/IAPS), 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, G. Piano (INAF/IAPS), F. Lucarelli (SSDC, and
INAF/OAR), A. Bulgarelli, V. Fioretti, F. Fuschino, N. Parmiggiani
(INAF/OAS-Bologna), M. Marisaldi (INAF/OAS-Bologna, and Bergen University),
M. Pilia, A. Trois (INAF/OA-Cagliari), F. Longo (Univ. Trieste and INFN
Trieste), I. Donnarumma (ASI), A. Giuliani (INAF/IASF-Mi), report on behalf
of the AGILE Team:

The AGILE satellite detected the long GRB 210702A at T0 = 2021-07-02
19:07:13 s (UTC), reported by Swift (GCNs #30351, #30352, #30356, #30358)
and CALET (#30362).

The burst is clearly visible in the AGILE scientific ratemeters of the
SuperAGILE (SA; 20-60 keV), MiniCALorimeter (MCAL; 0.4-100 MeV), and
AntiCoincidence (AC; 50-200 keV) detectors. The event lasted about ~32 s
and it released a total number of 1630 counts in the SA detector (above a
background rate of 50 Hz), 40500 counts in the MCAL detector (above a
background rate of 1440 Hz), and 74310 counts in the AC detector (above a
background rate of 3610 Hz). The AGILE ratemeter light curves can be found
at http://www.agilescienceapp.it/notices/GRB210702A_AGILE_RM.png . The
event also triggered a partial high time resolution MCAL data acquisition.

Additional analysis of AGILE data is in progress.


GRB_name: GRB210702A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30364
SUBJECT: GRB 210702A: iTelescope optical afterglow observations
DATE:    21/07/03 11:42:59 GMT
FROM:    Filipp Dmitrievich Romanov at Amateur astronomer  <filipp.romanov.27.04.1997@gmail.com>

I observed the field of GRB 210702A (Lien et al., GCN Circ. 30351)
using remote telescope T17 (0.43-m f/6.8 reflector + CCD) of
iTelescope.Net in Siding Spring Observatory (Australia) on 2021-07-03.
Two images were obtained from 09:00:31 UTC and from 09:01:57 UTC with
Sloan I filter (60 seconds exposures, BINx1) and one image was
obtained from 09:04:38 UTC with Sloan R filter (300 seconds exposure,
BINx1).

I detected optical afterglow with UVOT position in stacked image with
SI filter (mid time = 09:01:44 UTC, that is 13h 54m 31s after the
trigger) and in the image with SR filter (mid time = 09:07:08 UTC,
that is 13h 59m 55s after the trigger) and measured the following
magnitudes from comparison to magnitudes of nearby stars from APASS
DR9 catalogue (Henden et al., 2016): 18.6 i' +/- 0.4 and 19.0 r' +/-
0.5.

Magnitudes were not corrected for Galactic extinction.

Images available here: https://www.flickr.com/photos/filipp-romanov/51286698321


GRB_name: GRB210702A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30365
SUBJECT: GRB 210702A: Chilescope optical observations
DATE:    21/07/03 12:48:04 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI), A. Pozanenko (IKI), N. Pankov (HSE, IKI), M. Krugov 
(FAI)  report on behalf of GRB IKI FuN collaboration:

We observed the field of Swift GRB 210702A (Lien  et al., GCN 30351) 
with Chilescope RC-1000 starting on 2021-07-02 (UT)  23:40:26 in 
r'-filter. Within enhanced XRT position (D'Elia et al., GCN 30358) we 
clearly detect the afterglow (Lien  et al., GCN 30351; Lipunov et al., 
GCN 30352; Groot et al., GCN 30354; Kuin et al., GCN 30355; Kuin et al., 
GCN 30356; Xu et al., GCN 30357; Romanov  et al., GCN 30364).

Preliminary photometry of the afterglow is following

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

2021-07-02 23:40:26 0.193202 r' 1*600 17.01  0.05  19.7


The photometry is based on nearby stars from the APASS_DR8

RA DEC r
11:14:16.46880 -36:49:58.2132 15.187
11:14:36.96576 -36:48:30.0132 15.320


GRB_name: GRB210702A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30366
SUBJECT: Konus-Wind detection of GRB 210702A
DATE:    21/07/03 12:51:56 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

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

The long GRB 210702A (Swift detection: Lien et al., GCN 30351;
CALET GRBM detection: Yamaoka et al., GCN 30362;
AGILE detection: Ursi et al., GCN 30363)
triggered Konus-Wind (KW) at T0=68826.870 s UT (19:07:06.870).

The burst light curve shows a bright, FRED-like pulse
which starts at ~T0-4 s, and has a total duration of ~90 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/GRB210702_T68826/

As observed by Konus-Wind, the burst had
a fluence of (2.5 Â± 0.2)x10^-4 erg/cm^2 and
a 64-ms peak energy flux, measured from T0 + 7.808 s,
of (3.0 Â± 0.2)x10^-5 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+86.784 s)
is best fit in the 20 keV - 20 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.91 (-0.09,+0.10),
the high energy photon index beta = -1.91 (-0.10,+0.08),
the peak energy Ep = 376 (-61,+63) keV,
chi2 = 107/97 dof.

The spectrum near the peak count rate (measured from T0+4.096
to T0+7.936 s) is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.78 (-0.09,+0.11),
the high energy photon index beta = -2.00 (-0.09,+0.08),
the peak energy Ep = 402 (-64,+66) keV,
chi2 = 111/92 dof.

Assuming the redshift z=1.160 (Xu et al., GCN 30357)
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 isotropic energy release E_iso to ~9.3x10^53 erg,
the isotropic luminosity L_iso to ~2.4x10^53 erg/s,
the rest-frame peak energy of the time-integrated spectrum Epi,z to ~812 keV,
and the rest-frame peak energy of the 'peak' spectrum Epp,z to ~870 keV.
With these values, GRB 210702A is within 68% prediction bands
for both 'Amati' and 'Yonetoku' relations for the sample of >300 long KW GRBs
with known redshifts (Tsvetkova et al., 2021, ApJ, 908, 83),
see http://www.ioffe.ru/LEA/GRBs/GRB210702_T68826/GRB210702A_rest_frame.pdf

All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.


GRB_name: GRB210702A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30367
SUBJECT: GRB 210702A: BOOTES-3/YA optical counterpart observations
DATE:    21/07/04 11:59:24 GMT
FROM:    Youdong HU at IAA-CSIC  <huyoudong072@hotmail.com>

Y.-D. Hu, E. Fernandez-Garcia, T.-R. Sun, A. J. Castro-Tirado, M. D. Caballero-Garcia, M. A. Castro Tirado (IAA-CSIC), I. Carrasco and C. Perez del Pulgar (Univ. de Malaga), and R. Querel (NIWA), on behalf of a larger collaboration,
report:

The 60cm BOOTES-3/YA robotic telescope at NIWA Lauder in Otago (New Zealand) automatically responded to the Swift trigger of GRB 210702A (Lien et al. GCNC 30351), which also detected by CALET (Yamaoka et al. GCNC 30362) and AGILE (Ursi et al. GCNC 30363), after the twilight as soon as possible. The first image (clear filter) were obtained starting at 07:00:58 UT (~11.9 hrs after trigger). At the enhanced Swift/XRT position(D'Elia et al. GCNC 30358), we found the optical counterpart reported by MASTER (Lipunov et al. GCNC 30352), MeerLICHT (Groot et al. GCNC 30354), Swift/UVOT (Lien et al. GCNC 30351, Kuin et al. GCNC 30355), VLT (Xu et al. GCNC 30357), iTelescope (Romanov GCNC 30364) and Chilescope (Belkin et al. GCNC 30365) with a magnitude of R = 18.0+-0.1 in the co-added image (10 x 60 s), which calibrated with nearby stars in USNO-B 1.0 catalog. Further analysis is ongoing.

We thank the staff at NIWA for its excellent support.


GRB_name: GRB210702A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30368
SUBJECT: GRB 210702A, Swift-BAT refined analysis
DATE:    21/07/04 20:12:21 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

D. M. Palmer (LANL), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF),
S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), T. Sakamoto (AGU),
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(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 210702A (trigger #1058804)
(Lien et al., GCN Circ. 30351).  The BAT ground-calculated position is
RA, Dec = 168.570, -36.741 deg which is
   RA(J2000)  =  11h 14m 16.8s
   Dec(J2000) = -36d -44' -29.2"
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 4%.

The mask-weighted light curve shows a single-peaked FRED-like structure
that starts at ~T-4 s, peaks at ~T+1 s, and ends at ~T+370 s. The burst
went out of the BAT field of view at T+452 s. There might be addition
burst emission afterwards. T90 (15-350 keV) is 138.2 +- 47.6 sec
(estimated error including systematics).

The burst occurred at a location with a very low partial coding fraction,
and thus was out of the BAT calibrated field of view until ~T+18 s.
Therefore, the spectral analysis is only available for the burst duration
afterwards. The time-averaged spectrum from T+18.0 to T+369.2 sec is
best fit by a simple power-law model.  The power law index of the
time-averaged spectrum is 1.54 +- 0.09.  The fluence in the 15-150 keV
band is 9.8 +- 0.5 x 10^-6 erg/cm2. 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/1058804/BA/


GRB_name: GRB210704A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30369
SUBJECT: GRB 210704A: BALROG localization (Fermi Trigger 647120009 / GRB 210704815)
DATE:    21/07/04 20:33:32 GMT
FROM:    Jochen Greiner at MPE,Garching  <jcg@mpe.mpg.de>

F. Kunzweiler, B. Biltzinger, F. Berlato, J. Burgess & J. Greiner (all MPE Garching) report:

The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
647120009 at 19:33:24 on 04 July 2021 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) = 158.1+/-1.2 deg
Decl.(2000.0) = 58.3+/-0.5 deg
We estimate an additional systematic error of 1 deg.

Further details are available at:
https://grb.mpe.mpg.de/grb/GRB210704815/

The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB210704815/healpix

The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB210704815/json

                        


GRB_name: GRB210704A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30372
SUBJECT: GRB 210704A: AGILE/MCAL detection
DATE:    21/07/05 09:00:27 GMT
FROM:    Alessandro Ursi at INAF/IAPS  <alessandro.ursi@gmail.com>

A. Ursi (INAF/IAPS), 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, G. Piano (INAF/IAPS), F. Lucarelli (SSDC, and
INAF/OAR), A. Bulgarelli, V. Fioretti, F. Fuschino, N. Parmiggiani
(INAF/OAS-Bologna), M. Marisaldi (INAF/OAS-Bologna, and Bergen University),
M. Pilia, A. Trois (INAF/OA-Cagliari), I. Donnarumma (ASI), F. Longo (Univ.
Trieste and INFN Trieste), A. Giuliani (INAF/IASF-Mi), report on behalf of
the AGILE Team:

The AGILE Mini-CALorimeter (MCAL) detected the short GRB 210704A at T0 =
2021-07-04 19:33:25.27 +/- 0.01 s (UTC) (Fermi trigger no.647120009).

The event lasted about 1.06 s and released a total number of ~1333 counts
in the detector (in the 0.4-100 MeV energy range), above an average
background rate of 574 Hz. The MCAL light curve can be found at
http://www.agilescienceapp.it/notices/073773_GRB_552512005.278593.png . The
time-integrated spectrum of the burst can be fitted in the energy range
0.4-10 MeV with a single power-law with ph.ind. = -2.54 -0.28/+0.34,
resulting in a reduced chi-squared of 0.77 (48 d.o.f.) and a fluence of
2.9e-06 ergs/cm^2 (90% confidence level), in the same energy range.

The event is also clearly visible in the scientific ratemeters of the
SuperAGILE (SA; 18-60 keV), MiniCALorimeter (MCAL; 0.4-100 MeV), and
AntiCoincidence (AC; 50-200 keV) detectors. The burst released 450 counts
in the SA detector (above a background rate of 60 Hz), 5040 counts in the
MCAL detector (above a background rate of 1100 Hz), and 15540 counts in the
AC detector (above a background rate of 3570 Hz). The AGILE ratemeters
light curves can be found at:
http://www.agilescienceapp.it/notices/GRB210704A_AGILE_RM.png .

The AGILE-MCAL detector is a CsI detector with a 4 pi FoV, sensitive in the
energy range 0.4-100 MeV. 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: GRB210705A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30373
SUBJECT: GRB 210705A: AGILE/MCAL detection of a burst
DATE:    21/07/05 09:07:42 GMT
FROM:    Alessandro Ursi at INAF/IAPS  <alessandro.ursi@gmail.com>

A. Ursi (INAF/IAPS), 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, G. Piano (INAF/IAPS), F. Lucarelli (SSDC, and
INAF/OAR), A. Bulgarelli, V. Fioretti, F. Fuschino, N. Parmiggiani
(INAF/OAS-Bologna), M. Marisaldi (INAF/OAS-Bologna, and Bergen University),
M. Pilia, A. Trois (INAF/OA-Cagliari), I. Donnarumma (ASI), F. Longo (Univ.
Trieste and INFN Trieste), A. Giuliani (INAF/IASF-Mi), report on behalf of
the AGILE Team:

The AGILE Mini-CALorimeter (MCAL) detected a burst at T0 = 2021-07-05
05:26:25.67 +/- 0.01 s (UTC).

The event lasted about 0.32 s and released a total number of ~300 counts in
the detector (in the 0.4-100 MeV energy range), above an average background
rate of 586 Hz. The MCAL light curve can be found at
http://www.agilescienceapp.it/notices/073779_GRB_MCAL_552547585.675289.png .

The AGILE-MCAL detector is a CsI detector with a 4 pi FoV, sensitive in the
energy range 0.4-100 MeV. 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: GRB210704A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30374
SUBJECT: GRB 210704A: Swift ToO observations
DATE:    21/07/05 10:22:14 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

Swift has initiated a ToO observation of the Fermi/LAT GRB 210704A. 
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021454

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 Fermi/LAT 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: GRB210704A
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30375
SUBJECT: GRB 210704A: Fermi-LAT detection
DATE:    21/07/05 11:19:51 GMT
FROM:    Francesco Longo at U of Trieste,INFN Trieste  <franzlongo1969@gmail.com>

A. Berretta (University & INFN Perugia), F. Longo (University and
INFN, Trieste),
M. Axelsson (KTH & Stockholm Univ.), E. Bissaldi (Politecnico and INFN, Bari),
F. Piron (CNRS/IN2P3/LUPM) and M. Arimoto (Kanazawa Univ.)
report on behalf of the Fermi-LAT Collaboration:

On July 4th, 2021, Fermi-LAT detected high-energy emission from GRB 210704A
which was also detected by Fermi-GBM (trigger 647120009/210704815) and
by AGILE/MCAL (GCN 30372).

The best LAT on-ground location is found to be
RA, Dec = 159.08, 57.31 (degrees, J2000)
with an error radius of 0.11 deg (90% containment, statistical error only).
This was 63 deg from the LAT boresight at the time of the GBM trigger:
T0 = 19:33:24.59 UT.

The data from the Fermi-LAT show a very significant increase
in the event rate after the GBM trigger that is temporally and spatially
correlated with the GBM emission with high significance.

The photon flux above 100 MeV in the time interval 0-10s after the GBM trigger
is (1.60 +/- 0.31) E-03 ph/cm2/s.
The estimated photon index above 100 MeV is -1.74 +/- 0.13.
The highest-energy photon is a 16 GeV event which is observed 1.5 seconds
after the GBM trigger.

The Fermi-LAT point of contact for this burst is Alessandra Berretta
(alessandra.berretta@pg.infn.it).

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


GRB_name: GRB210704A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30378
SUBJECT: GRB 210704A: AstroSat CZTI detection
DATE:    21/07/05 15:15:59 GMT
FROM:    Gaurav Waratkar at IIT,Bombay  <gauravwaratkar@iitb.ac.in>

 V. Prasad (IUCAA), P. Sawant (IUCAA), G. Waratkar (IITB), A. Vibhute
(IUCAA), V. Bhalerao (IITB), D. Bhattacharya (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,
2020, arxiv:2011.07067) showed detection of a short GRB 210704A, which
was also detected by Fermi - GBM (Trigger 647120009 / GRB210704815),
Fermi-LAT (GCN 30375), and AGILE/MCAL (GCN 30372). 

The source was clearly detected in the 20-200 keV energy range. The
light curve showed multiple peaks of emission with the strongest peak at
2021-07-04 19:33:24.4 UT. The measured peak count rate associated with
the burst is 706 (+179, -132) cts/s above the background in the combined
data of four quadrants, with a total of 359 (+106, -109) cts. The local
mean background count rate was 489 (+6, -8) cts/s. Using cumulative
rates, we measure a T90 of 1.0 (+0.4, -0.4) s.  

It was also clearly detected in the CsI anticoincidence (Veto) detector
in the 100-500 keV energy range. In one-second bins, the measured peak
count rate associated with the burst is 1417.7 (+89.9 -97.4) cts/s above
the background in the combined data of four quadrants, with a total of
2430 (+327 -361) cts. The local mean background count rate was 1743.4
(+4.2 -4.2) cts/s. 

CZTI GRB detections are reported regularly on the payload site at
http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led
consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC
and PRL. The Indian Space Research Organisation funded, managed and
facilitated the project.


GRB_name: GRB210704A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30379
SUBJECT: GRB 210704A: Swift-XRT afterglow detection
DATE:    21/07/05 15:34:15 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A. D'Ai (INAF-IASFPA), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto),
B. Sbarufatti (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U.
Leicester), A. Melandri (INAF-OAB), T. Sbarrato (INAF-OAB) and P.A.
Evans (U. Leicester) report on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Fermi/LAT-detected burst GRB 210704A (Berretta et al. GCN Circ. 30375),
collecting 2.6 ks of Photon Counting (PC) mode data between T0+53.5 ks
and T0+61.1 ks. 

An uncatalogued X-ray source is detected and is above the 2SXPS 3-sigma
upper limit at this position, and is therefore likely the GRB
afterglow. Using 2378 s of PC mode data and 2 UVOT images, we find an
enhanced XRT position (using the XRT-UVOT alignment and matching UVOT
field sources to the USNO-B1 catalogue): RA, Dec = 159.02219, +57.21636
which is equivalent to:

RA (J2000): 10h 36m 05.33s
Dec(J2000): +57d 12' 58.9"

with an uncertainty of 3.2 arcsec (radius, 90% confidence). This
position is 5.9 arcmin from the Fermi/LAT 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/00021454.
The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/ToO_GRBs/00021454.

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


GRB_name: GRB210704A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30380
SUBJECT: GRB 210704A: Fermi GBM detection
DATE:    21/07/05 17:43:24 GMT
FROM:    Christian Malacaria at NASA-MSFC/USRA  <cmalacaria@usra.edu>

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

"At 19:33:24.59 UT on 04 July 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210704A (trigger 647120009 / 210704815),
which was also detected by Fermi-LAT (Berretta et al. 2021, GCN 30375), 
AGILE/MCAL (Ursi et al. 2021, GCN 30372), AstroSat/CZTI (Prasad et al. 2021, GCN 30378)
and Swift/XRT (D'Ai et al. 2021, GCN 30379).

The Fermi-GBM on-ground calculated location is consistent with the Swift/XRT position.
The angle from the Fermi LAT boresight at the GBM trigger time is 63 degrees.

The GBM light curve consists of a main bright peak
with a duration (T90) of about 4.7 s (50-300 keV).
The time-averaged spectrum from T0+0.2 s to T0+1.8 s is
best fit by a Band function with Epeak = 286.1 +/- 6.4 keV,
alpha = -0.35 +/- 0.02, and beta = -2.91 +/- 0.12 .

The event fluence (10-1000 keV) in this time interval is
(1.95 +/- 0.02)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.5 s in the 10-1000 keV band
is 75.9 +/- 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: GRB200704A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30381
SUBJECT: GRB 200704A: possible local hosts
DATE:    21/07/05 18:32:51 GMT
FROM:    Andrew Levan at U.of Leicester  <a.levan@astro.ru.nl>

A.J. Levan (Radboud), S. Campana (INAF-OAB), D.A. Kann (HETH/IAA-CSIC), P D'Avanzo (INAF-OAB) report:

â€œWe note that the Swift XRT localisation (Dâ€™Ai et al. GCN 30379) of GRB 210704A detected by Fermi-LAT, Fermi-GBM (Kunzweiler et al. GCN 30369, Malacaria et al. GCN 30380), AGILE (Ursi et al. GCN 30722) and AstroSat (Prasad et al. GCN 30378) lies in a significant galaxy overdensity. Of particular note, the source localisation overlaps the galaxy cluster 400d J1036+5713 at z=0.203. Although there are no apparent galaxies within the XRT localisation visible in the PanSTARRS 3pi imaging of the field, there are numerous likely members of this cluster within a few arcseconds. 

Furthermore, an even brighter foreground galaxy WISEA J103604.24+571327.7 lies offset approximately 30â€ from the XRT position and has a reported redshift of z=0.0817. This galaxy has I=15.962 +/- 0.007 (and absolute magnitude around -22). Its projected physical offset from the burst position is approximately 45 kpc. Although this offset is significant, the probability of chance alignment remains small.

The burst itself appears dominated by a short-spike, with a fainter tail of emission, and these possible host galaxies are consistent with the hosts and locations of short GRBs (and not of long GRBs). At z=0.203 (or z=0.0891) the isotropic equivalent energy would be E_iso ~ 2e51 erg (or E_iso ~ 3e50 erg at z=0.0891), consistent with SGRBs.

Observations to search for the optical afterglow or possibly rising kilonova emission are strongly encouraged. â€œ


GRB_name: GRB210704B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30382
SUBJECT: GRB 210704B: Fermi GBM detection
DATE:    21/07/05 18:33:57 GMT
FROM:    Christian Malacaria at NASA-MSFC/USRA  <cmalacaria@usra.edu>

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

At 16:25:18.89  UT on 04 July 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210704B (trigger 647108723 / 210704684).

The on-ground calculated location, using the GBM trigger
data, is RA = 203.44, DEC = -41.87 (J2000 degrees,
equivalent to 13 h 33 m, -41 d 52 '), with a statistical uncertainty
of 1.00 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a 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 87 degrees.

The GBM light curve shows multiple peaks
with a duration (T90) of about 43.5 s (50-300 keV).
The time-averaged spectrum from T0-0.5 s to T0+8.7 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.64 +/- 0.06 and
the cutoff energy, parameterized as Epeak, is 350.8 +/- 26.3 keV.

The event fluence (10-1000 keV) in this time interval is
(8.1 +/- 0.4)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+28.6 s in the 10-1000 keV band
is 16.1 +/- 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: GRB210704A
Detection_method: Fermi LAT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30383
SUBJECT: GRB 210704A: DDOTI upper limit
DATE:    21/07/05 18:47:55 GMT
FROM:    Simone Dichiara at UMCP/NASA/GSFC  <dichiara@umd.edu>

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

We observed the field of the Fermi/LAT GRB 210704A (Berretta et al. GCN
Circ. 30375, Ursi et al. GCN Circ. 30372, Malacaria et al. GCN Circ. 30380)
with the DDOTI wide-field imager at the Observatorio AstronÃ³mico Nacional
on Sierra San Pedro Martir (http://ddoti.astroscu.unam.mx) starting from
2021-07-05 04:51 to 05:01 UTC (from 9 hours after the trigger). We obtained
a 360 seconds of total exposure in the w filter.

We find no new sources within the XRT error region reported by D'Ai et al.
(GCN Circ. 30379) . Calibrating our images against the APASS catalog we
obtained a 5-sigma limiting magnitude of w = 19.7.
Compared to the USNO-B1, Pan-STARRS DR1, and APASS DR10 catalogs, we detect
no uncataloged sources to our limit.

We also noticed the presence of a galaxy cluster at z~0.2 coincident with
the afterglow localization region and the presence of a bright galaxy about
30" north from the X-ray transient.

We thank the staff of the Observatorio Astronomico Nacional in San Pedro
Martir.


GRB_name: GRB210704A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30384
SUBJECT: GRB 210704A: Assy optical afterglow candidate
DATE:    21/07/05 20:32:34 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

V. Kim (FAI, Pulkovo Observatory), A. Pozanenko (IKI), M. Krugov (FAI), 
   S. Belkin (IKI), N. Pankov (HSE, IKI) report on behalf of GRB IKI FuN:

We observed the field of  GRB 210704A Fermi-LAT (Berretta et al. 2021, 
GCN 30375), AGILE/MCAL (Ursi et al. 2021, GCN 30372), AstroSat/CZTI 
(Prasad et al. 2021, GCN 30378), Swift/XRT (D'Ai et al. GCN 30379), and 
Fermi-GBM (Malacaria et al. GCN 30380) with AZT-20 telescope of 
Assy-Turgen observatory starting on 2021-07-05 (UT) 17:42:41.27.

In a stacked image we detect only one object  near enhanced XRT position 
(D'Ai et al. GCN 30379). Coordinates of the object are (J2000) 
10:36:04.88 +57:12:58.5 with uncertainty of 0.5 arcsec in both coordinates.

Preliminary photometry of the object is following

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

2021-07-05 17:42:41.27  0.94407  66*60  r'      22.25  0.13  23.0

The photometry is based on the nearby SDSS-DR12 stars.
The object is not presented in the SDSS DR12, nor in PS1 catalogue. We 
suggest the object is the afterglow of GRB 210704A.


GRB_name: GRB210704A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30385
SUBJECT: GRB 210704A: TNG detection of the optical afterglow candidate
DATE:    21/07/05 23:15:32 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <pda.davanzo@gmail.com>

P. D'Avanzo (INAF-OAB), V. D'Elia (ASI-SSDC), A. Fiorenzano, C. Padilla (INAF-TNG) on behalf of the CIBO collaboration report:

We observed the field of GRB 210704A (Kunzweiler et al., GCN Circ. 30369; Ursi et al., GCN Circ. 30372; Berretta et al., GCN Circ. 30375; 
Prasad et al., GCN 30378; Malacaria et al. GCN 30380), covering the position of the X-ray afterglow reported by D'Ai et al. (GCN Circ. 30379) 
with the Italian 3.6m TNG telescope equipped with the optical camera DOLORES. A series of images were obtained with the r-sdss filter on 
2021-07-05 from 21:13:11 UT to 21:39:50 UT (i.e. about 1.08 days after the burst).  

The optical afterglow candidate reported by Kim et al. (GCN Circ. 30384) is clearly detected at the following position (J2000): 
RA: 10:36:04.92
Dec: +57:12:59.3
(+/- 0.5"). 


With preliminary photometry we derive the following magnitude:
r = 22.13  +/- 0.13 

(AB; calibrated against the SDSS catalogue). 

As noted by  Kim et al. (GCN Circ. 30384), this source is not visible in archival SDSS and Pan-STARRS images. 


GRB_name: GRB210619B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30386
SUBJECT: GRB 210619B: ALMA detection
DATE:    21/07/06 02:19:43 GMT
FROM:    Tanmoy Laskar at U of Bath  <tanmoylaskar@gmail.com>

T. Laskar (University of Bath), K. D. Alexander (Northwestern), E. Berger
(Harvard), W. Fong (Northwestern), R. Margutti (Northwestern), C. G.
Mundell (University of Bath), and P. Schady (University of Bath) report on
behalf of a larger collaboration:

"We observed GRB 210619B (D'Avanzo et al. GCN 30261) with the Atacama Large
Millimeter/Submillimeter Array (ALMA) at 97.5 GHz beginning on 2021 June 25
06:53:48 UT (5.29 days after the burst). ALMA observations of this burst
were delayed due to a major snowstorm at the array.

Preliminary analysis reveals a mm source with flux density of ~ 0.1 mJy at
position:

RA (J2000) = 21:18:52.349 (+/- 0.002)
Dec (J2000) = +33:51:01.40 (+/- 0.04)

consistent with the X-ray position (Beardmore et al. GCN 30267) and optical
position (D'Avanzo et al., GCN 30261; Kuin et al. GCN 30278).

We thank the JAO staff, AoD, P2G, and the entire ALMA team for their help
with these observations."


GRB_name: GRB210704B
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30387
SUBJECT: GRB 210704B: AstroSat CZTI detection
DATE:    21/07/06 04:14:59 GMT
FROM:    Gaurav Waratkar at IIT,Bombay  <gauravwaratkar@iitb.ac.in>

V. Prasad (IUCAA), P. Sawant (IUCAA), G. Waratkar (IITB), A. Vibhute
(IUCAA), V. Bhalerao (IITB), D. Bhattacharya (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,
2020, arxiv:2011.07067) showed detection of a long GRB 210704B, which
was also detected by Fermi - GBM (Malacaria et al. 2021, GCN 30382). 

The source was clearly detected in the 20-200 keV energy range. The
light curve showed multiple peaks of emission with the strongest peak at
2021-07-04 16:25:47.5 UT. The measured peak count rate associated with
the burst is 296 (+47, -39) cts/s above the background in the combined
data of four quadrants, with a total of 3398 (+476, -466) cts. The local
mean background count rate was 552 (+2, -3) cts/s. Using cumulative
rates, we measure a T90 of 37 (+8, -7) s. 

It was also clearly detected in the CsI anticoincidence (Veto) detector
in the 100-500 keV energy range. The Veto light curve showed multiple
peaks of emission with the strongest peak at 2021-07-04 16:25:46.7 UT.
The measured peak count rate is 1642 (+95, -104) cts/s above the
background in the combined Veto data of four quadrants, with a total of
18239 (+789, -1081) cts. The local mean background count rate was 1864
(+5, -5) cts/s. We measure a T90 of 34 (+9, -3) s from the cumulative
Veto light curve. 

CZTI GRB detections are reported regularly on the payload site at
http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led
consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC,
and PRL. The Indian Space Research Organisation funded, managed, and
facilitated the project.


GRB_name: GRB210704A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30388
SUBJECT: Konus-Wind detection of GRB 210704A
DATE:    21/07/06 09:51:51 GMT
FROM:    Anna Ridnaia at Ioffe Institute  <ridnaia@mail.ioffe.ru>

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

The long-duration GRB 210704A
(BALROG localization: Kunzweiler et al., GCN 30369;
AGILE/MCAL detection: Ursi et al., GCN 30372;
Fermi-LAT detection: Berretta et al., GCN 30375;
AstroSat CZTI detection: Prasad et al., GCN 30378;
Fermi GBM detection: Malacaria & Meegan, GCN 30380)
triggered Konus-Wind at T0=70400.814 s UT (19:33:20.814).

The burst light curve shows a bright peak
in the interval from ~T0 to ~T0+2 s followed by
a weaker pulse peaked at ~T0+4.5 s.
The emission is seen up to ~4 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB210704_T70400/

As observed by Konus-Wind, the burst
had a fluence of 2.25(-0.12,+0.14)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+0.528 s,
of 3.31(-0.37,+0.39)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+1.536 s)
is best fit in the 20 keV - 4 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.21(-0.09,+0.10),
the high energy photon index beta = -2.97(-0.31,+0.22),
the peak energy Ep = 271(-14,+14) keV
(chi2 = 56/57 dof).

The spectrum near the maximum count rate
(measured from T0+0.256 to T0+0.768 s)
is best fit in the 20 keV - 4 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.20(-0.12,+0.13),
the high energy photon index beta = -2.84(-0.40,+0.25),
the peak energy Ep = 320(-24,+27) keV
(chi2 = 44/53 dof).

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


GRB_name: GRB210704A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30389
SUBJECT: GRB 210704A: Swift/UVOT Upper Limits
DATE:    21/07/06 10:16:25 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL) and A. Y. Lien (GSFC/UMBC) report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210704A 53458 s after the LAT trigger 
(Kunzweiler et al., GCN Circ. 30369).
No optical afterglow consistent with the XRT position (D'Ai et al. GCN Circ. 30379) nor the optical 
positions given by Kim et al., (GCN Circ. 30384) and D'Avanzo et al., (GCN Circ. 30385) 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

v                53458        72068         3038         >21.1

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


GRB_name: GRB210704A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30390
SUBJECT: GRB 210704A: RATIR optical upper limits
DATE:    21/07/06 11:51:23 GMT
FROM:    Eleonora Troja at NASA/GSFC/UMD  <eleonora@umd.edu>

Eleonora Troja (GSFC), Nat Butler (ASU), Alan M. Watson (UNAM),
Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G.
Richer (UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC),
Josh Bloom (UCB), Antonino Cucchiara (UVI), Owen Littlejohns (ASU),
Enrico Ramirez-Ruiz (UCSC), Jesus GonzÃ¡lez (UNAM), Carlos
Roman-Zuniga (UNAM), Harvey Moseley (GSFC), John Capone (UMD),
V. Zach Golkhou (U. Wash.), and Vicki Toy (UMD) report:

We observed the field of GRB 210704A (Berretta et al. GCN 30375,
Ursi et al. GCN 30372, Malacaria et al. GCN 30380) with the
Reionization and Transients Infrared Camera (RATIR) on the 1.5m
Harold Johnson Telescope at the Observatorio Astronomico Nacional on
Sierra San Pedro Martir. The target was visible from 2021/07 6.17 to
2021/07 6.18 UTC (30.72 to 31.18 hours after the BAT trigger), and we
obtained a total of 0.37 hours exposure in the r and i bands.

No source is detected at the position of the candidate optical counterpart
(Kim et al. GCN 30384, D'Avanzo et al. GCN 30385). In comparison with the
SDSS DR9 catalog, we obtain the following upper limits (3-sigma):

  r > 22.4
  i > 22.1

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.

We thank the staff of the Observatorio Astronomico Nacional in San Pedro
Martir.

Further observations are planned.


GRB_name: GRB210704A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30391
SUBJECT: GRB 210704A: CAHA 2.2m Afterglow Detection
DATE:    21/07/06 12:12:22 GMT
FROM:    Alexander Kann at IAA-CSIC  <kann@iaa.es>

D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC, 
DARK/NBI), C. Thoene, M. Blazek, J. F. Agui Fernandez (all 
HETH/IAA-CSIC), and P. Martin-Fernandez (CAHA) report:

We observed the afterglow of GRB 210704A (BALROG localization: 
Kunzweiler et al., GCN #30369; Fermi/LAT detection: Berretta et al., GCN 
#30375; Fermi/GBM detection: Malacaria & Meegan, GCN #30382; AGILE/MCAL 
detection: Ursi et al., GCN #30372; AstroSat/CZTI detection: Prasad et 
al., GCN #30378; Konus-Wind detection: Ridnaia et al., GCN #30388; 
Swift/XRT afterglow detection: D'Ai et al., GCN #30379) with CAFOS 
mounted at the 2.2m Calar Alto telescope (Almeria, Spain), under good 
conditions but at high airmass. We obtained 5 x 300 s images in i'.

The optical afterglow (Kim et al., GCN #30384, D'Avanzo et al., GCN 
#30385) is faintly detected in the stacked image. Against four 
Pan-STARRS comparison stars, we derive a preliminary measurement of i' = 
21.84 +/- 0.13 mag at 1.09286 â€‹d after the trigger.

Compared to contemporary observations (D'Avanzo et al., GCN #30385), the 
r' - i' color is unremarkable, indicating the afterglow likely does not 
suffer from high extinction, and is therefore intrinsically faint. If it 
is associated with the surrounding galaxy cluster (Levan et al., GCN 
#30381), this would add evidence to the merger-induced ("short") nature 
of the event.


GRB_name: GRB210704A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30392
SUBJECT: GRB 210704A: OSIRIS/GTC spectroscopy
DATE:    21/07/06 14:24:06 GMT
FROM:    Antonio de Ugarte Postigo at IAA-CSIC  <deugarte@iaa.es>

A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), D. A. Kann, 
C. Thoene, M. Blazek, J. F. Agui Fernandez (all HETH/IAA-CSIC),
J. P. U Fynbo (DAWN/NBI), L. Izzo (DARK/NBI), N. R. Tanvir (U. Leicester), 
G. Lombardi, A. Marante (both GTC) report:

We observed the afterglow of GRB 210704A (BALROG localization: 
Kunzweiler et al., GCN #30369; Fermi/LAT detection: Berretta et al., 
GCN #30375; Fermi/GBM detection: Malacaria & Meegan, GCN #30382; 
AGILE/MCAL detection: Ursi et al., GCN #30372; AstroSat/CZTI detection: 
Prasad et al., GCN #30378; Konus-Wind detection: Ridnaia et al., GCN 
#30388; Swift/XRT afterglow detection: D'Ai et al., GCN #30379; optical 
afterglow: Kim et al., GCN #30384, D'Avanzo et al., GCN #30385, Kann et 
al. GCN #30391) with OSIRIS, mounted on the 10.4 m GTC telescope, at 
the Roque de los Muchachos observatory (La Palma, Spain). The 
observation consisted of 2x60s acquisition images in r-band followed by 
4x600s spectra with grism R1000B, covering the spectral range between 
3700 and 7800 AA. The observation started at 21:48:57 UT (26.26 hr after 
the burst) and the combined spectrum has an average epoch of 22:18:25 
UT (26.75 hr after the burst).

The afterglow is well detected in the acquisition image at an r-band 
magnitude of 22.40 +/- 0.07 as compared to several SDSS field stars. The 
spectrum shows continuum above 3800 AA with a typical SNR of 5 above 
5000 AA. 

The detection of continuum down to 3800 AA implies an upper limit on the 
redshift of z < 3.15.

We do not detect any absorption or emission features at the redshift of the 
field galaxy (z = 0.0817) or field cluster (z = 0.203) reported in by Levan et 
al. in GCN #30381. However, a featureless spectrum would be expected 
if this event were a short GRB in an intracluster environment.

We note that there is a tentative detection of a broad dip in the continuum at 
~ 4050 AA, that could be identified as due to Ly-alpha. However, we caution 
that the SNR in this part of the spectrum is very low. This would imply a 
redshift of z = 2.34, and could be sustained by further low-significance 
detections of OI, SiII and CII. However, we also note that at this redshift 
there is no detection of CIV, nor SiIV, which is uncommon but not 
unprecedented. 

The spectrum is publicly available for inspection at GRBSpec.eu.


GRB_name: GRB210706A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30393
SUBJECT: GRB 210706A: Swift/BAT-GUANO detection and arcminute localization
DATE:    21/07/06 18:22:57 GMT
FROM:    Aaron Tohuvavohu at U Toronto  <aaron.tohu@gmail.com>

Aaron Tohuvavohu (U Toronto), James DeLaunay (PSU), Jamie A. Kennea
(PSU), Gayathri Raman (PSU) report:

Swift/BAT did not trigger on GRB 210706A (T0: 2021-07-06 08:17:49.9
UTC, Fermi/GBM trigger #  647252274).

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

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

The burst is detected in BAT with a duration of approximately 10 seconds.
The burst occurred during a Swift slew.
Using the normal BAT imaging technique, we find the location for
the GRB with an SNR of 19.

The BAT position is
RA, Dec = 312.0124 +13.3079 deg which is
   RA(J2000)  = 20h 48m 02.98s
   Dec(J2000) =  +13d 18â€² 28.4â€³
with an estimated uncertainty of 5 arcmin.

This position is consistent with the Ferm/GBM localization.

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: GRB210706A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30397
SUBJECT: GRB 210706A: Swift ToO observations
DATE:    21/07/06 20:19:06 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

Swift has initiated a ToO observation of the Swift/BAT-GUANO GRB 210706A. 
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021455

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 Swift/BAT-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: GRB210706A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30399
SUBJECT: GRB 210706A: Swift-XRT afterglow detection
DATE:    21/07/07 01:18:21 GMT
FROM:    Aaron Tohuvavohu at U Toronto  <aaron.tohu@gmail.com>

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

Swift-XRT has performed follow-up observations of the
Swift/BAT-GUANO-detected burst GRB 210706A (Tohuvavohu et al. GCN Circ.
30393), collecting 2.8 ks of Photon Counting (PC) mode data between
T0+43.3 ks and T0+50.7 ks. 

Two uncatalogued X-ray sources are detected, of which one ("Source 2")
is believed to be the afterglow. Using 2536 s of PC mode data and 2
UVOT images, we find an enhanced XRT position (using the XRT-UVOT
alignment and matching UVOT field sources to the USNO-B1 catalogue):
RA, Dec = 311.99471, +13.31694 which is equivalent to:

RA (J2000): 20h 47m 58.73s
Dec(J2000): +13d 19' 01.0"

with an uncertainty of 3.2 arcsec (radius, 90% confidence). This
position is 69 arcsec from the Swift/BAT-GUANO position.  The source
has a mean count rate of 1.4e-02 ct/sec; we cannot determine at the
present time whether it is fading.

The field has been previously observed by XRT for the Swift
Gravitational Wave Galaxy Survey (https://www.swift.ac.uk/SGWGS/, GCN
24305). No source was detected at this position on a 2.8 ks integrated
exposure, down to a 3-Ïƒ upper limit of 7 e-3 ct s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00021455.
The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/ToO_GRBs/00021455.

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


GRB_name: GRB210704A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30401
SUBJECT: GRB 210704A: OAJ T80 multi-color detections
DATE:    21/07/07 10:40:21 GMT
FROM:    Alexander Kann at IAA-CSIC  <kann@iaa.es>

D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC, 
DARK/NBI), C. Thoene, M. Blazek, J. F. Agui Fernandez (all 
HETH/IAA-CSIC), N. Maicas, and J. L. Lamadrid (COAJ report:

We observed the afterglow of GRB 210704A (BALROG localization: 
Kunzweiler et al., GCN #30369; Fermi/LAT detection: Berretta et al., GCN 
#30375; Fermi/GBM detection: Malacaria & Meegan, GCN #30382; AGILE/MCAL 
detection: Ursi et al., GCN #30372; AstroSat/CZTI detection: Prasad et 
al., GCN #30378; Konus-Wind detection: Ridnaia et al., GCN #30388; 
Swift/XRT afterglow detection: D'Ai et al., GCN #30379) with the T80 
0.8m telescope at the Observatorio de Javalambre (Teruel, Spain). 
Observations consisted of 3 x 300 s in z', i', g' r' each, at midtimes 
1.081, 1.093, 1.104, and 1.116 days after the GRB, respectively.

The afterglow (Kim et al., GCN #30384, D'Avanzo et al., GCN #30385, Kann 
et al., GCN #30391, de Ugarte Postigo et al., GCN #30392) is 
well-detected in g'r', faintly in i' and not in z'. Against four 
Pan-STARRS field stars, we measure (AB magnitudes):

g' = 22.42 +/- 0.11 mag;
r' = 22.17 +/- 0.10 mag;
i' = 22.08 +/- 0.23 mag;
z' > 21.5 mag

at the above-mentioned mid-times.


GRB_name: GRB210706A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30402
SUBJECT: GRB 210706A: GIT optical upper limits
DATE:    21/07/07 12:39:54 GMT
FROM:    Harsh Kumar at Indian Inst of Tech,Bombay  <harshkosli13@gmail.com>

H. Kumar (IITB), R. Norbu (IAO), V. Bhalerao (IITB), G. C. Anupama (IIA),
S. Barway (IIA) report on behalf of the GIT team:

We observed GRB 210706A detected by Swift/BAT-GUANO (see A. Tohuvavohu et
al. GCN #30393) with 0.7m GROWTH-India Telescope (GIT). We obtained
multiple 100-second images in g', r' and i' bands, interspersed with each
other. The total exposure in each band was 1000 seconds. We did not detect
any new source in our stacked images within the 3.2 arcsec circle, around
the swift XRT position centered at RA: 20h 47m 58.73s Dec: +13d 19' 01.0"
(GCN #30399). Also, we did not detect any new transient within the full 5
arcmin circle around the Swift/BAT-GUANO position (GCN #30393). The
obtained upper limit follow as:

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

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

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

  2459402.343657 | 11.95 |  g' | > 20.86 |

  2459402.346588 | 12.02 |  r' | > 21.00 |

  2459402.349518 | 12.09 |  i' | > 20.32 |

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

The magnitudes are calibrated against PanSTARRS (Flewelling et al., 2018)
and not corrected for Galactic extinction.

The GROWTH India Telescope (GIT) is a 70-cm telescope with a 0.7-degree
field of view, set up by the Indian Institute of Astrophysics and the
Indian Institute of Technology Bombay with support from the Indo-US Science
and Technology Forum (IUSSTF) and the Science and Engineering Research
Board (SERB) of the Department of Science and Technology (DST), Government
of India (https://sites.google.com/view/growthindia/). It is located at the
Indian Astronomical Observatory (Hanle), operated by the Indian Institute
of Astrophysics (IIA).


GRB_name: GRB210706A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30403
SUBJECT: Konus-Wind detection of GRB 210706A
DATE:    21/07/07 13:05:45 GMT
FROM:    Anna Ridnaia at Ioffe Institute  <ridnaia@mail.ioffe.ru>

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

The long-duration GRB 210706A
(Fermi GBM trigger 647252274;
Swift/BAT-GUANO detection: Tohuvavohu et al., GCN 30393)
triggered Konus-Wind at T0=29875.487 s UT (08:17:55.487).

The burst light curve shows a multipeaked structure
started at ~T0-2.7 s with a total duration of ~8.9 s.
The emission is seen up to ~4 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB210706_T29875/

As observed by Konus-Wind, the burst
had a fluence of 5.39(-0.66,+0.90)x10^-6 erg/cm2,
and a 64-ms peak flux, measured from T0+1.040 s,
of 2.73(-0.92,+0.99)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 4 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -1.11(-0.26,+0.30)
and Ep = 263(-59,+112) keV (chi2 = 65/71 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.3
(chi2 = 65/70 dof).

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


GRB_name: GRB210706A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30404
SUBJECT: GRB 210706A: optical upper limit of Sintesz-Newton/CrAO and AS-32/AbAO
DATE:    21/07/07 13:44:19 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

N. Pankov (IKI, HSE), S. Nazarov (CrAO), R. Ya. Inasaridze (AbAO), A. 
Pozanenko (IKI), S. Belkin (IKI, HSE)  report on behalf of IKI GRB FuN:

We observed the filed of Swift/BAT-GUANO detection GRB 210706A 
(Tohuvavohu   et al., GCN 30393),  GRB 210706A also triggered Konus-Wind 
(Ridnaia et al., GCN 30403) with Sintesz-Newton 350mm f/5 telescope of 
CrAO observatory and AS-32 telescope of Abastumani observatory (AbAO). 
Observation started on 2021-07-06 (UT) 22:52:40 and consist of 6 images 
of 300 s exposure in Clear filter (Sintesz-Newton) and in R-filter (UT) 
2021-07-06 (UT) 20:23:40 (AS-32). In bothe telescopes we cover the whole 
localization region of Swift/BAT-GUANO (Tohuvavohu   et al., GCN 30393). 
We find no new optical sources in either of the two XRT candidates 
(https://www.swift.ac.uk/ToO_GRBs/00021455/). In particular no source 
was detected in XRT afterglow candidate #2 (Tohuvavohu   et al., GCN 30399).

Upper limit for of the stacked image is following

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

2021-07-06 20:23:40   0.50719 R      9*60    n/d  n/d    20.5  AS-32
2021-07-06 22:52:40   0.60755 Clear  6*300   n/d  n/d    21.5  Newton


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

Our non-detections is consistent with results of GROWTH-India Telescope 
(Kumar  et al., GCN 30402).


GRB_name: GRB210706A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30405
SUBJECT: GRB 210706A: Fermi GBM observation
DATE:    21/07/07 14:13:18 GMT
FROM:    Elisabetta Bissaldi at 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 08:17:49.86 UT on 6 July 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210706A (trigger 647252274 / 210706346),
which was also detected by the Swift/BAT-GUANO pipeline
(Tohuvavohu et al. 2021, GCN 30393).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight
at the GBM trigger time is 86 degrees.

The GBM light curve consists of a single emission episode
with a duration (T90) of about 7 s (50-300 keV).
The time-averaged spectrum from T0-0.1 s to T0+5.1 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -1.35 +/- 0.04 and
the cutoff energy, parameterized as Epeak, is 590 +/- 130 keV.

The event fluence (10-1000 keV) in this time interval is
(6.0 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+1.5 s in the 10-1000 keV band
is 12.1 +/- 0.3 ph/s/cm^2.


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

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


GRB_name: GRB210704A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30411
SUBJECT: GRB 210704A: CAHA 2.2m telescope optical limit
DATE:    21/07/07 22:53:14 GMT
FROM:    Youdong HU at IAA-CSIC  <huyoudong072@hotmail.com>

T.-R. Sun, Y.-D. Hu, E. Fernandez-Garcia, A. J. Castro-Tirado  M. D. Caballero-Garcia, M. A. Castro Tirado (IAA-CSIC), P. Martin-Fernandez (CAHA) on behalf of a larger collaboration, report:

Following the detection of GRB210704A by Fermi (Kunzweiler et al. GCNC 30369), AGILE (Ursi et al. GCNC 30372), AstroSat (Prasad et al. GCNC 30378) and Konus-Wind (Ridnaia et al. GCNC 30388), we triggered the 2.2m CAHA telescope (+ CAFOS) at the Calar Alto Observatory (Almeria, Spain). A series of r-band images were gathered starting on July 6, 20:40 UT (i.e. 2.05 day post trigger). On the co-added image (9 x 300s), no optical object is detected down to 22.7 mag at the afterglow position reported by Swift/XRT (Evans et al. GCNC 30374), Assy (Kim et al. GCNC 30384) and TNG (D'Avanzo et al. GCNC 30385). Combined with the additional detections (de Ugarte Postigo et al. GCNC 30392, Kann et al. GCNC 30391, Kann et al. GCNC 30401), the optical afterglow decaying lightcurve is confirmed.

We thank the staff at Calar Alto observatory for their excellent support.


GRB_name: GRB210708A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30413
SUBJECT: GRB 210708A: Swift detection of a burst
DATE:    21/07/08 02:40:32 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

B. Sbarufatti (PSU), H. A. Krimm (NSF), S. Laha (GSFC/UMBC/CRESST),
A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC),
D. M. Palmer (LANL), M. H. Siegel (PSU) and A. Tohuvavohu (U Toronto)
report on behalf of the Neil Gehrels Swift Observatory Team:

At 02:25:37 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 210708A (trigger=1059460).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 173.699, -49.187 which is 
   RA(J2000) = 11h 34m 48s
   Dec(J2000) = -49d 11' 11"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of about 10 sec.  The peak count rate
was ~1300 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 02:26:37.5 UT, 60.5 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 173.73706, -49.15179 which is
equivalent to:
   RA(J2000)  = 11h 34m 56.89s
   Dec(J2000) = -49d 09' 06.4"
with an uncertainty of 12.2 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.  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 (1.58 x
10^21 cm^-2, Willingale et al. 2013), with an excess column of 3.5
(+3.01/-2.55) x 10^21 cm^-2 (90% confidence). 

UVOT data is not immediately available, possibly due to a bright
star (mag=5.5) within 1 arcminute of the XRT location. 

Burst Advocate for this burst is B. Sbarufatti (bxs60 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: GRB210707A
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30414
SUBJECT: GRB 210707A: A long GRB detected by INTEGRAL
DATE:    21/07/08 06:19:43 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 50 s has been detected by IBAS in the
 IBIS/ISGRI data at 22:25:05 UT of 2021 July 7.   The corresponding WEAK
type Alert Packet with the burst position was distributed in real time
 (Alert n. 9296).

The refined coordinates (J2000) are:
R.A.= 192.5460 deg
DEC.=  -63.2763 deg
with an uncertainty of  3   arcmin (90% c.l.).

The burst had a peak flux of  0.2  ph/cm2/s (20-200 keV, 1-s integration
time) and a fluence in the same energy range of about 5e-7 erg/cmq.

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


GRB_name: GRB210708A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30416
SUBJECT: GRB 210708A: Swift-XRT refined Analysis
DATE:    21/07/08 10:42:33 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

We have analysed 6.8 ks of XRT data for GRB 210708A (Sbarufatti et al.
GCN Circ. 30413), from 85 s to 22.8 ks after the  BAT trigger. The data
are entirely in Photon Counting (PC) mode. The refined XRT position is
RA, Dec = 173.7372, -49.1515 which is equivalent to:

RA (J2000): 11 34 56.92
Dec(J2000): -49 09 05.4

with an uncertainty of 7.0 arcsec (radius, 90% confidence).

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.76 (+0.30, -0.65).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.5 (+0.4, -0.3). The
best-fitting absorption column is  3.0 (+1.2, -1.0) x 10^21 cm^-2, in
excess of the Galactic value of 1.6 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 3.0 x 10^-11 (5.8 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      3.0 (+1.2, -1.0) x 10^21 cm^-2
Galactic foreground: 1.6 x 10^21 cm^-2
Excess significance: 2.2 sigma
Photon index:      2.5 (+0.4, -0.3)

If the light curve continues to decay with a power-law decay index of
1.76, the count rate at T+24 hours will be 8.8 x 10^-6 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.6 x
10^-16 (5.1 x 10^-16) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01059460.

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


GRB_name: GRB210708B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30417
SUBJECT: GRB 210708B: Swift detection of a possible burst
DATE:    21/07/08 13:51:47 GMT
FROM:    Hans Krimm at NSF/NASA-GSFC  <hkrimm@nsf.gov>

B. Sbarufatti (PSU), P. A. Evans (U Leicester), H. A. Krimm (NSF),
K. L. Page (U Leicester), D. M. Palmer (LANL) and
A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 13:23:24 UT, the Swift Burst Alert Telescope (BAT) triggered and
located possible GRB 210708B (trigger=1059494).  
The BAT on-board calculated location is 
RA, Dec 142.579, +14.471 which is 
   RA(J2000) = 09h 30m 19s
   Dec(J2000) = +14d 28' 16"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single-peaked
structure with a duration of about 100 sec.  The peak count rate
was ~1400 counts/sec (15-350 keV), at ~6 sec after the trigger. 

Due to a Sun observing constraint, Swift cannot slew to the BAT
position until 05:03 UT on 2021 September 30. There will thus be no XRT
or UVOT data for this trigger before this time. 

Due to a discrepancy between the on-board and ground analysis with
the limited data available, we cannot definitively determine
whether this is an astrophysical event.  Further analysis will
be done after the ground telemetry pass. 

Burst Advocate for this burst is B. Sbarufatti (bxs60 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: GRB210707A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30420
SUBJECT: Fermi GBM Sub-Threshold Detection of GRB 210707A
DATE:    21/07/08 16:49:47 GMT
FROM:    Cori Fletcher at USRA  <cfletcher@usra.edu>

C. Fletcher (USRA) reports on behalf of the Fermi-GBM Team:

INTEGRAL/IBAS detected GRB 210707A at 22:25:05 UT (GCN 30414). There was no
Fermi-GBM onboard trigger around the event.

An automated, blind search for short gamma-ray bursts below the onboard
triggering threshold in Fermi-GBM identified no counterparts.

The GBM targeted search [1], the most sensitive, coherent search for
GRB-like signals identified a transient most significantly on the 8.192 s
timescale, with a false alarm rate of 6.4e-06 Hz and a location consistent with
the INTEGRAL/IBAS event, using the standard search protocol with a S/N of 15.
The GBM targeted search event was found with the highest
significance with a "norm" spectrum (Band function with
Epeak = 230 keV, alpha = -1.0, beta = -2.3) for a GRB.

[1] Goldstein et al. 2019 arXiv:1903.12597


GRB_name: GRB210708A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30421
SUBJECT: Fermi GBM Sub-Threshold Detection of GRB 210708A
DATE:    21/07/08 16:52:18 GMT
FROM:    Cori Fletcher at USRA  <cfletcher@usra.edu>

C. Fletcher (USRA) reports on behalf of the Fermi-GBM Team:

Swift-BAT detected GRB 210708A at 02:25:37 UT (GCN 30413). There was no
Fermi-GBM onboard trigger around the event.

An automated, blind search for short gamma-ray bursts below the onboard
triggering threshold in Fermi-GBM identified no counterparts.

The GBM targeted search [1], the most sensitive, coherent search for
GRB-like signals identified a transient most significantly on the 4.096 s
timescale, with a false alarm rate of 1.7e-04 Hz and a location consistent with
the Swift-BAT event, using the standard search protocol with a S/N of 6.
The GBM targeted search event was found with the highest
significance with a "soft" spectrum (Band function with
Epeak = 70 keV, alpha = -1.9, beta = -3.7) for a GRB.

[1] Goldstein et al. 2019 arXiv:1903.12597


GRB_name: GRB210708A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30422
SUBJECT: GRB 210708A: Swift-BAT refined analysis
DATE:    21/07/08 18:08:58 GMT
FROM:    Hans Krimm at NSF/NASA-GSFC  <hkrimm@nsf.gov>

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

Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 210708A (trigger #1059460)
(Sbarufatti, et al., GCN Circ. 30413).  The BAT ground-calculated position is
RA, Dec = 173.759, -49.164 deg which is 
  RA(J2000)  =  11h 35m 02.3s 
  Dec(J2000) = -49d 09' 50.2" 
with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 94%.

The mask-weighted light curve shows a single peak of duration about 3 seconds,
starting just before T0.   T90 (15-350 keV) is 2.77 +- 0.70 sec (estimated error 
including systematics).

The time-averaged spectrum from T-0.69 to T+2.44 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.05 +- 0.29.  The fluence in the 15-150 keV band is 1.1 +- 0.2 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.14 sec in the 15-150 keV band
is 0.8 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1059460/BA/


GRB_name: GRB210702A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30423
SUBJECT: GRB 210702A: ALMA detection
DATE:    21/07/08 18:26:27 GMT
FROM:    Tanmoy Laskar at U of Bath  <tanmoylaskar@gmail.com>

T. Laskar (University of Bath) and D. Perley (LJMU) report on behalf of a
larger collaboration:

"We observed GRB 210702A (Lien et al. GCN 30351) with the Atacama Large
Millimeter/Submillimeter Array (ALMA) at 97.5 GHz and 343.5 GHz beginning
on 2021 July 03 21:05:52 UT (26.0 h after the burst). ALMA observations of
this burst were delayed due to uninterruptible scheduled Cycle 8 software
validation at the Observatory.

Preliminary analysis reveals a mm source with flux density of ~ 0.1 mJy at
97.5 GHz and position:

RA (J2000) = 11:14:18.807
Dec (J2000) = -36:44:49.25

with uncertainty ~ 0.03" in each coordinate, consistent with the X-ray
position (D'Elia et al., GCN 30358) and optical position (Lien et al., GCN
30351; Kuin et al., GCN 30356). The spectrum appears strongly self-absorbed
in the mm-band. Further observations are planned.

We thank the JAO staff, AoD, P2G, and the entire ALMA team for their help
with these observations."


GRB_name: GRB210702A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30424
SUBJECT: GRB 210702A: ATCA detection
DATE:    21/07/08 18:32:53 GMT
FROM:    Tanmoy Laskar at U of Bath  <tanmoylaskar@gmail.com>

T. Laskar (University of Bath), S. Bhandari (CSIRO), K. D. Alexander
(Northwestern), E. Berger (Harvard), R. Chornock (UC Berkeley), D.
Coppejans (Northwestern), M. Drout (U. Toronto), H. van Eerten (University
of Bath), Wen-fai Fong (Northwestern), C. Guidorzi (U. Ferrara), R.
Margutti (UC Berkeley), C. G. Mundell (University of Bath), P. Schady
(University of Bath), and G. Schroeder (Northwestern) report:

"We observed GRB 210702A (Lien et al., GCN 30351) with the Australia
Telescope Compact Array (ATCA) at multiple frequencies beginning on 2021
July 06 05:00 UT. We detect a radio counterpart at 16.7, 21.2, and 34 GHz
at a position consistent with the X-ray position (D'Elia et al., GCN
30358), optical position (Lien et al., GCN 30351; Kuin et al., GCN 30356),
and mm-band position (Laskar et al., GCN 30423) with a flux density of ~
0.8 mJy at 34 GHz at a mid-time of 3.50 days after the burst.

Further observations are planned.

We thank the CSIRO staff for approving and scheduling these observations."


GRB_name: GRB210708A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30425
SUBJECT: GRB 210708A: Swift/UVOT Upper Limits
DATE:    21/07/08 20:24:24 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <mhs18@psu.edu>

M. H. Siegel (PSU) and B. Sbarufatti (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210708A
121 s after the BAT trigger (Sbarufatti et al., GCN Circ. 30413).
No optical afterglow consistent with the XRT position
(Sbarufatti et al. GCN Circ. 30413) is detected in the initial UVOT exposures.
We note that the XRT position is close to the bright star HD 100708,
the brightness of which may obscure a faint afterglow.
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               121          370          246         >19.4
v                  427         4406          236         >19.6
b                  377         5077          108         >19.3
u                  121         5021          481         >19.4
w1                 476         4816          236         >18.9
m2                 452         4611          236         >19.4
w2                 403         4201          236         >19.5

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.160 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB210708B
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30426
SUBJECT: Swift GRB 210708B: Global MASTER-Net observations report 
DATE:    21/07/08 23:21:27 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

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

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

D. Buckley 
(South African Astronomical Observatory),

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

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

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




MASTER-IAC robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Spain (IAC Teide Observatory) was pointed to the Swift GRB 210708B ( B. Sbarufatti et al., GCN 30417) errorbox  27094 sec after notice time and 27800 sec after trigger time at 2021-07-08 21:06:45 UT, with upper limit up to  16.5 mag. Observations started at twilight.  The observations began at zenith distance = 79 deg. The sun  altitude  is -13.0 deg. 

MASTER-OAFA robotic telescope  located in Argentina (OAFA observatory of San Juan National University) was pointed to the Swift GRB 210708B errorbox  34540 sec after notice time and 35247 sec after trigger time at 2021-07-08 23:10:51 UT, with upper limit up to  17.2 mag. The observations began at zenith distance = 77 deg. The sun  altitude  is -17.6 deg. 

The galactic latitude b = 42 deg., longitude l = 218 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1655856

We obtain a following upper limits.  

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

   27891 |          MASTER-IAC |   C |   180 | 16.5 |        
   35337 |         MASTER-OAFA |   C |   180 | 17.2 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB210709A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30427
SUBJECT: GRB 210709A: Fermi GBM Final Real-time Localization
DATE:    21/07/09 04:59:22 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 04:49:04 UT on 9 Jul 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210709A (trigger 647498949.307986 / 210709201).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 295.3, Dec = -44.2 (J2000 degrees, equivalent to J2000 19h 41m, -44d 12'), with a statistical uncertainty of 3.9 degrees.

The angle from the Fermi LAT boresight is 75.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210709201/quicklook/glg_skymap_all_bn210709201.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210709201/quicklook/glg_healpix_all_bn210709201.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210709201/quicklook/glg_lc_medres34_bn210709201.gif


GRB_name: GRB210709A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30428
SUBJECT: Fermi GRB 210709A: Global MASTER-Net observations report 
DATE:    21/07/09 06:00:08 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

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

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

D. Buckley 
(South African Astronomical Observatory),

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

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

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




MASTER-IAC robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Spain (IAC Teide Observatory) started inspect of the Fermi GRB 210709A ( Fermi GBM team, GCN 30427) errorbox  121 sec after notice time and 150 sec after trigger time at 2021-07-09 04:51:34 UT, with upper limit up to  16.2 mag. Observations started at twilight.  The observations began at zenith distance = 85 deg. The sun  altitude  is -16.2 deg. 

MASTER-OAFA robotic telescope  located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 210709A errorbox  162 sec after notice time and 191 sec after trigger time at 2021-07-09 04:52:15 UT, with upper limit up to  18.9 mag. The observations began at zenith distance = 15 deg. The sun  altitude  is -80.9 deg. 

The galactic latitude b = -28 deg., longitude l = 355 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1656291

We obtain a following upper limits.  

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

     165 | 2021-07-09 04:51:34 |          MASTER-IAC | (19h 53m 28.95s , -45d 39m 58.5s) |  P| |    30 | 16.0 |        
     165 | 2021-07-09 04:51:34 |          MASTER-IAC | (19h 52m 20.20s , -45d 33m 36.3s) |  P- |    30 | 15.0 |        
     206 | 2021-07-09 04:52:15 |         MASTER-OAFA | (19h 50m 50.37s , -44d 56m 51.2s) |   C |    30 | 17.8 |        
     220 | 2021-07-09 04:52:24 |          MASTER-IAC | (19h 53m 28.65s , -45d 38m 59.8s) |  P| |    40 | 16.0 |        
     220 | 2021-07-09 04:52:24 |          MASTER-IAC | (19h 52m 19.93s , -45d 32m 38.3s) |  P- |    40 | 15.2 |        
     261 | 2021-07-09 04:53:04 |         MASTER-OAFA | (19h 50m 47.04s , -44d 55m 48.4s) |   C |    40 | 18.1 |        
     285 | 2021-07-09 04:53:24 |          MASTER-IAC | (19h 53m 35.38s , -45d 40m 01.8s) |  P| |    50 | 16.2 |        
     285 | 2021-07-09 04:53:24 |          MASTER-IAC | (19h 52m 26.65s , -45d 33m 40.9s) |  P- |    50 | 15.1 |        
     325 | 2021-07-09 04:54:04 |         MASTER-OAFA | (19h 50m 46.92s , -44d 57m 13.3s) |   C |    50 | 18.2 |        
     360 | 2021-07-09 04:54:34 |          MASTER-IAC | (19h 53m 29.54s , -45d 41m 03.4s) |  P| |    60 | 16.2 |        
     360 | 2021-07-09 04:54:34 |          MASTER-IAC | (19h 52m 20.76s , -45d 34m 42.9s) |  P- |    60 | 15.2 |        
     400 | 2021-07-09 04:55:14 |         MASTER-OAFA | (19h 50m 50.12s , -44d 55m 29.0s) |   C |    60 | 18.4 |        
     637 | 2021-07-09 04:58:40 |          MASTER-IAC | (19h 39m 58.96s , -44d 16m 07.4s) |  P| |   120 | 15.8 |        
     637 | 2021-07-09 04:58:40 |          MASTER-IAC | (19h 38m 52.40s , -44d 09m 49.2s) |  P- |   120 | 13.6 |        
     684 | 2021-07-09 04:59:28 |         MASTER-OAFA | (19h 37m 03.50s , -43d 35m 29.7s) |   C |   120 | 18.6 |        
     834 | 2021-07-09 05:01:48 |         MASTER-OAFA | (19h 37m 10.23s , -43d 35m 29.7s) |   C |   140 | 18.8 |        
     962 | 2021-07-09 05:03:40 |          MASTER-IAC | (19h 39m 48.98s , -44d 16m 42.0s) |  P| |   170 | 14.9 |        
    1009 | 2021-07-09 05:04:28 |         MASTER-OAFA | (19h 37m 06.16s , -43d 34m 06.7s) |   C |   170 | 18.9 |        
    1204 | 2021-07-09 05:07:37 |         MASTER-OAFA | (19h 37m 06.08s , -43d 35m 44.2s) |   C |   180 | 18.9 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB210708B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30429
SUBJECT: GRB 210708B: Swift-BAT refined analysis
DATE:    21/07/09 10:39:56 GMT
FROM:    Hans Krimm at NSF/NASA-GSFC  <hkrimm@nsf.gov>

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

Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 210708B (trigger #1059494)
(Sbarufatti, et al., GCN Circ. 30417).  The BAT ground-calculated position is
RA, Dec = 142.594, 14.523 deg which is 
   RA(J2000)  =  09h 30m 22.5s 
   Dec(J2000) = +14d 31' 22.6" 
with an uncertainty of 2.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 74%.

The mask-weighted light curve shows a broad peak with some sub-structure.
Emission begins around T-100 sec, peaks near the trigger time and decays
to background by T+200 sec.  The burst position was not in the field of view of
the BAT until about T-150 sec.  T90 (15-350 keV) is 298.43 +- 47.32 sec 
(estimated error including systematics).

The time-averaged spectrum from -99.8 to 263.7 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.62 +- 0.26.  The fluence in the 15-150 keV band is 2.2 +- 0.4 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+2.84 sec in the 15-150 keV band
is 0.0 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 

We note that in the original GCN circular, the event was described as a possible
burst.  Analysis of the full data set shows that the event is indeed a GRB.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1059494/BA/


GRB_name: GRB210706A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30431
SUBJECT: GRB 210706A: Swift/XRT afterglow confirmation
DATE:    21/07/09 13:23:26 GMT
FROM:    Aaron Tohuvavohu at U Toronto  <aaron.tohu@gmail.com>

A. Tohuvavohu (U. Toronto) and K.L. Page (U. Leicester) report on
behalf of the Swift-XRT team:

Swift-XRT has performed further follow-up observations of the
Fermi/GBM (E. Bissaldi et al. GCN 30405) and Swift/BAT-GUANO detected
burst GRB 210706A (Tohuvavohu et al., GCN Circ. 30393), collecting 9.5
ks
of Photon Counting (PC) mode data between T0+43 ks and T0+180 ks.

The uncatalogued X-ray source (src #2) detected in the first 2.8 ks of
data as the GRB afterglow candidate  (Tohuvavohu et al. GCN 30399),
which was above existing upper limits at this location from previous
XRT observations, has faded significantly in the latest observation,
and is thus confirmed as the X-ray afterglow of the burst.

The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/xrt_curves/00021455/.

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


GRB_name: GRB210704A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30432
SUBJECT: GRB 210704A: further TNG optical observations
DATE:    21/07/09 20:36:50 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <pda.davanzo@gmail.com>

P. D'Avanzo (INAF-OAB), V. D'Elia (ASI-SSDC), S. Campana (INAF-OAB), M. De Pasquale (Istanbul Univ.), A. Melandri (INAF-OAB), 
A. Rossi (INAF-OAS), R. Salvaterra (INAF-IASF Mi), G. Tagliaferri (INAF-OAB), M. Cecconi, A. Garcia de Gurtubai Escudero (INAF-TNG) 
on behalf of the CIBO collaboration report:

We carried out further observations of the optical afterglow of GRB 210704A (Kim et al. GCN Circ. 30384; D'Avanzo et al. GCN Circ. 30385) 
with the Italian 3.6m TNG telescope equipped with the optical camera DOLORES. A series of images were obtained with the i-sdss and r-sdss 
filters on 2021-07-08 from 21:22:44 UT to 22:36:58 UT (i.e. about 4.1 days after the burst) under non optimal seeing conditions (2").  

A faint source, possibly extended, is detected at the optical afterglow position. With preliminary photometry we derive the following magnitudes: 
r = 23.35 +/- 0.16 
i = 23.39 +/- 0.14

(AB; calibrated against the SDSS catalogue). 
Because of the seeing conditions and the source faintness we cannot definitely confirm if the source is extended or point-like. 


Further deep optical observations are encouraged to monitor the light curve evolution and to check if there is any contribution 
from an underlying host galaxy. 


GRB_name: GRB210704A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30433
SUBJECT: GRB 210704A: Gemini-North Infrared Source Detection
DATE:    21/07/09 21:48:13 GMT
FROM:    Jillian Rastinejad at Northwestern Univ.  <jillianrastinejad2024@u.northwestern.edu>

J. Rastinejad (Northwestern), A. Levan (Radboud U.), W. Fong (Northwestern), N. R. Tanvir (U. Leicester) and A. Rouco Escorial (Northwestern) report on behalf of a larger collaboration:

We observed the location of GRB 210704A (Kunzweiler et al., GCN 30369; Ursi et al., GCN 30372; Berretta et al., GCN 30375; Prasad et al., GCN 30378; D'Ai et al., GCN 30379) with the Near-Infrared Imager (NIRI) mounted on Gemini-North under Program GN-2021A-Q-109. We obtained 14x60-sec imaging in K-band at a mid-time of 2021 July 9.265 UT (4.45 days post-burst) at an average airmass of 2.1. We detect a faint source consistent with the location of the optical afterglow (Kim et al., GCN 30384; D'Avanzo et al., GCN 30385; Troja et al., GCN 30390; Kann et al., GCN 30391, 30401; Sun et al., GCN 30411). Calibrated to 2MASS and applying the standard AB conversion, we measure a brightness of K_AB = 22.9 +/- 0.3 mag. At present, it is not possible to discern whether the source is point-like or extended, and the degree to which any underlying host galaxy may be contributing (c.f., D'Avanzo et al., GCN 30432). 

For comparison, we note that the expected approximate brightness for a kilonova of the same luminosity as GW170817/AT2017gfo at z~0.08 (Levan et al., GCN 30381) is K_AB ~ 22.5 mag at this epoch. Scaled to the nearby galaxy cluster redshift of z~0.2 (Levan et al., GCN 30381; Dichiara et al. GCN 30383), the expected magnitude for such a kilonova becomes K_AB ~ 24.6 mag, considerably fainter than the source detected here. On the other hand, it is plausible that the detected NIR source is a background galaxy at higher redshift (de Ugarte Postigo et al., GCN 30392; D'Avanzo et al., GCN 30432). Concurrent and continued multi-band follow-up is encouraged to discern the nature of this source.

Further NIR observations are planned to assess any variability of the source. We thank the Gemini staff for the rapid scheduling and execution of these observations.


GRB_name: GRB210704A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30436
SUBJECT: GRB 210704A: OSIRIS/GTC Observations and Archival Detection of the Possible Host Galaxy 
DATE:    21/07/10 07:23:45 GMT
FROM:    Alan M Watson at UNAM  <alan@astro.unam.mx>

Alan M. Watson (UNAM), Eleonora Troja (GSFC/UMD), Rosa L. Becerra (UNAM), RubÃ©n
SÃ¡nchez (INAF),  Aishwarya Thakur (INAF), Simone Dichiara (GSFC/UMD), Nat Butler
(ASU), William H. Lee (UNAM), OcÃ©lotl Lopez (UNAM), Margarita Pereyra (UNAM),
and Srihari Ravi (ASU) report:

We observed the field of GRB 210704A (Berretta et al., GCN Circ. 30375; D'Ai et
al., GCN Circ. 30379; Malacaria & Meegan, GCN Circ. 30380; Kim et al., GCN Circ.
30384) with the OSIRIS instrument on the 10.4 meter GTC telescope.

We observed at two epochs. The first epoch was at 2.10 days after burst and the
second at 5.10 days after burst.  At both epochs, we detect a source at the
position of the candidate optical afterglow (Kim et al., GCN Circ. 30384) at a
magnitude consistent with the TNG observations of r~23.3 at 4.1 days (D'Avanzo
et al., GCN Circ. 30432). We also resolve a second fainter (r~24.5 AB mag)
source (S2) located 0.7 arcsec E and 2.4 arcsec S of the OT position.

Our observations indicate only a marginal fading of about 0.2 magnitudes in the
r-band between our two epochs, which is unusually shallow for a GRB afterglow or
for a kilonova.

Archival pre-explosion images of the field reveal the presence of an underlying
faint source (S1), which might be the host galaxy. Based on a deep exposure
obtained in 2012 with the MegaPrime/MegaCam, we estimate a magnitude of r~25.3
+/- 0.2 AB mag for S1. The source S2 is also detected in archival images at a
magnitude consistent with our GTC observations.

Assuming no intrinsic variability, S1 would only partially contribute to the
observed optical light (~25%) and this by itself is not sufficient to explain
the slow fading of the optical emission. Given the ambiguous classification of
the gamma-ray emission, whose duration lies at the intersection between short
and long GRBs, we cannot exclude that the observed flattening marks the onset of
an associated supernova.

Further observations to monitor the evolution of this source are encouraged.

We thank David Garcia and Antonio Cabrera for assistance with these
observations.


GRB_name: GRB210704A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30440
SUBJECT: GRB 210704A: Assy optical afterglow upper limit
DATE:    21/07/10 23:24:16 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

N. Pankov (HSE, IKI), S. Belkin (IKI), V. Kim (FAI, Pulkovo 
Observatory), A. Pozanenko (IKI), M. Krugov (FAI)  report on behalf of 
GRB IKI FuN:

We observed GRB 210704A  (Ursi et al., GCN 30372; Berretta et al., GCN 
30375; Prasad et al., GCN 30378; D'Ai et al., GCN 30379; Malacaria et 
al., GCN 30380; Ridnaia et al., GCN 30388)  with AZT-20 telescope of 
Assy-Turgen observatory starting on 2021-07-08 (UT) 16:59:54. We do not 
detect the optical afterglow (Kim et al., GCN 30384; D'Avanzo et al., 
GCN 30385; Troja et al., GCN 30390; Kann et al., GCN 30391, 30401; Sun 
et al., GCN 30411; D'Avanzo et al., GCN 30432; Rastinejad  et al., GCN 
30433;  Watson et al., GCN 30436).

Preliminary photometry of the filed is following

Date       UT start  t-T0       Exp.   Filter  OT    Err.  UL(3sigma)
                     (mid, days)  (s)
2021-07-08 16:59:54  3.92014    77*60    r'    n/d   n/d   23.1

The photometry is based on the nearby PS1 stars.

Our photometry is consistent with observations of (D'Avanzo et al., GCN 
30432; Watson et al., GCN 30436).


GRB_name: GRB210704A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30442
SUBJECT: GRB210704A: Gemini near-infrared upper limits
DATE:    21/07/11 17:24:24 GMT
FROM:    Eleonora Troja at NASA/GSFC/UMD  <eleonora@umd.edu>

E. Troja (UMD/GSFC), A. Watson (UNAM), B. O'Connor (UMD/GSFC/GWU) report on
behalf of a larger collaboration:

We observed the field of GRB 210704A (Ursi et al., GCN 30372; Berretta et
al., GCN 30375; Malacaria et al. GCN 30380) with the Near-Infrared Imager
(NIRI) mounted on the 8.1m Gemini North telescope. We obtained 24x60 s
imaging in J-band starting on 2021 July 10 at 06:00 UT (~5.5 days after the
GRB) at an average airmass of 2.0.

At the location of the optical afterglow (Kim et al., GCN 30384) we detect
no source. Preliminary calibration against nearby 2MASS objects yields a
3-sigma upper limit of J>23.5 AB mag.  With respect to the earlier
observations reported by Rastinejad et al. (GCN 30433), our data show a
marginal evidence of fading.

We note that nearly simultaneous Swift/XRT observations still detect the
X-ray afterglow at a flux level of  ~4.4E-14 erg/cm2/s at 4.5 d after the
burst. By using a spectral index of about 0.85, consistent with the
Swift/XRT spectrum (https://www.swift.ac.uk/xrt_spectra/00021454/) and the
observed temporal decay with slope ~1.3, we estimate an
afterglow contribution of ~23.1 AB mag to the nIR emission.  This suggests
that the non-thermal afterglow component could have significantly
contributed to the nIR detection reported in Rastinejad et al. (GCN 30433).

We thank the Gemini staff for scheduling and executing these observations.


GRB_name: GRB210704A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30443
SUBJECT: GRB 210704A: NOT optical observations and color change
DATE:    21/07/11 20:07:25 GMT
FROM:    Luca Izzo at DARK/NBI  <luca.izzo@gmail.com>

D. A. Kann (HETH/IAA-CSIC), L. Izzo (DARK/NBI), F. J. Galindo Guil, and A. Kasikov (NOT) report:

We observed the optical afterglow (Kim et al., GCN #30384; D'Avanzo et al., GCN #30385; Kann et al., GCN #30391; de Ugarte Postigo et al., GCN #30392; Kann et al., GCN #30401; Sun et al., GCN #30411; D'Avanzo et al., GCN #30432; Rastinejad et al., GCN #30433; Watson et al., GCN #30436; Pankov et al., GCN #30440; Troja et al., GCN #30442) of GRB 210704A (Kunzweiler et al., GCN #30369; Ursi et al., GCN #30372; Berretta et al., GCN #30375; Prasad et  al., GCN #30378; D'Ai et al., GCN #30379; Malacaria et al. GCN #30380; Ridnaia et al., GCN #30388) with the AlFOSC imager mounted on the Nordic Optical Telescope (NOT) located in La Palma, Spain.

We have obtained 3x300s images in the g' and r' filters, at a mean epoch of 6.085 days and 6.096 days after the GRB, respectively. The optical afterglow is still detected in each stacked image, and we measure g' = 23.78 +/- 0.11 mag, r' = 23.27 +/- 0.09 mag against Pan-STARRS comparison stars (AB system).

This suggests that the optical transient has hardly changed in brightness for several days compared to earlier measurements (D'Avanzo et al., GCN #30432; Watson et al., GCN #30346), while remaining two magnitudes brighter than the potential host galaxy (Watson et al., GCN #30436).

On the other hand, the g' - r' color has increased compared to the measurement of Kann et al., GCN #30401, a behavior expected both for a SN component and a KN component, but not an afterglow. As the temporal evolution is also peculiar for a fast-evolving KN, the interpretation as a rising SN gains credence (Watson et al., GCN #30436). The magnitude, however, may be indicative of a redshift exceeding those indicated by a nearby galaxy and somewhat more distant galaxy cluster (Levan et al., GCN #30381).


GRB_name: GRB210704A
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30444
SUBJECT: GRB 210704A: INTEGRAL observations
DATE:    21/07/11 22:27:18 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

Minaev, P., Pozanenko, A.,  Chelovekov, I., Grebenev, S. report on 
behalf of GRB IKI FuN:

We report results of analysis  of INTEGRAL observations of GRB 210704A. 
We used  publicly available data. GRB 210704A was initially reported by 
X-/gamma-ray experiments (Ursi et al., GCN 30372; Berretta et al., GCN 
30375; Prasad et al., GCN 30378; D'Ai et al., GCN 30379; Malacaria et 
al., GCN 30380; Ridnaia et al., GCN 30388). The burst was detected by 
SPI-ACS at (UTC) 2021-07-04T19:33:24.5. Its duration in the SPI-ACS 
energy band (> 80 keV) is T_90 = 3.5 +/- 0.7 s. Comparing fluences of 
long-duration GRBs simultaneously recorded by SPI-ACS and Fermi/GBM 
(Chelovekov et al., in preparation) we estimated the GRB 210704A fluence 
to be 1.8e-5 erg/cm^2 in the 10-1000 keV band (the 95% confidence region 
which includes systematics was 5.2e-6 â€“ 6.3e-5 erg/cm^2).  We did not 
detect any signature of an extended emission in the SPI-ACS energy band 
(> 80 keV). GRB 210704A was also detected by ISGRI detector as 106 
degrees off-axis event.  The light curve of both SPI-ACS and ISGRI can 
be found at

http://grb.rssi.ru/GRB210704A/GRB20210704A_ISGRI_ACS.png


GRB_name: GRB210704A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30445
SUBJECT: GRB 210704A: Continued Gemini-North NIR K-band Detections
DATE:    21/07/12 02:16:53 GMT
FROM:    Wen-fai Fong at Northwestern U  <wfong@northwestern.edu>

W. Fong and J. Rastinejad (Northwestern) report on behalf of a larger collaboration:

We continue to observe GRB 210704A (Kunzweiler et al., GCN 30369; Ursi et al., GCN 30372; Berretta et al., GCN 30375; Prasad et al., GCN 30378; D'Ai et al., GCN 30379) with the Near-Infrared Imager (NIRI) mounted on Gemini-North under Program GN-2021A-Q-109. We obtained two additional epochs of K-band imaging on 2021-07-10 and 2021-07-11 UT at mid-times of 5.47 days and 6.45 days for 34x60-sec and 43x60-sec, respectively. The infrared source (Rastinejad et al., GCN 30433) is still detected in both epochs, with a brightness of K_AB = 23.2 +/- 0.2 mag at 6.45 days. Performing digital image subtraction between these epochs and our initial imaging at 4.5 days, we find no clear evidence for any significant changes in brightness.

In addition, the source is clearly point-like in our most recent imaging, indicating that there is not a significant contribution from a host galaxy to the NIR flux at this time (consistent with the same conclusion reached in the optical bands, Watson et al., GCN 30436; Kann et al., GCN 30443). The fairly flat temporal evolution of the NIR source over ~4.5-6.5 days is consistent with the contemporaneous optical behavior (D'Avanzo et al., GCN 30432; Kann et al., GCN 30443), and is also at odds with a pure, fading afterglow origin, as previously noted (Watson et al., GCN 30436; Kann et al., GCN 30443).

We thank the Gemini staff for the rapid scheduling and execution of these observations.


GRB_name: GRB210709A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30446
SUBJECT: GRB 210709A: AstroSat CZTI detection
DATE:    21/07/12 04:44:57 GMT
FROM:    Gaurav Waratkar at IIT,Bombay  <gauravwaratkar@iitb.ac.in>

V. Prasad (IUCAA), P. Sawant (IUCAA), G. Waratkar (IITB), A. Vibhute
(IUCAA), V. Bhalerao (IITB), D. Bhattacharya (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,
2020, arxiv:2011.07067) showed detection of a long GRB 210709A, which
was also detected by Fermi-GBM (GCN 30427).

The source was clearly detected in the 20-200 keV energy range. The
light curve showed multiple peaks of emission with the strongest peak at
2021-07-09 04:49:04.5 UT. The measured peak count rate associated with
the burst is 201 (+40, -42) cts/s above the background in the combined
data of four quadrants, with a total of 909 (+221, -239) cts. The local
mean background count rate was 386 (+4, -4) cts/s. Using cumulative
rates, we measure a T90 of 14 (+4, -4) s. 

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

CZTI GRB detections are reported regularly on the payload site at
http://astrosat.iucaa.in/czti/?q=grb [1]. CZTI is built by a TIFR-led
consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC,
and PRL. The Indian Space Research Organisation funded, managed, and
facilitated the project. 

Links:
------
[1] http://astrosat.iucaa.in/czti/?q=grb


GRB_name: GRB210712A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30447
SUBJECT: GRB 210712A: Swift detection of a burst
DATE:    21/07/12 09:58:21 GMT
FROM:    Hans Krimm at NSF/NASA-GSFC  <hkrimm@nsf.gov>

B. Sbarufatti (PSU), H. A. Krimm (NSF) and K. L. Page (U Leicester)
report on behalf of the Neil Gehrels Swift Observatory Team:

At 09:43:11 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 210712A (trigger=1059881).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 97.337, -35.393 which is 
   RA(J2000) = 06h 29m 21s
   Dec(J2000) = -35d 23' 33"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single-peaked
structure with a duration of about 20 sec, followed by lower-level 
extended emission.  The peak count rate was ~2600 counts/sec (15-350 keV), 
at ~0 sec after the trigger. 

The XRT began observing the field at 09:44:32.5 UT, 80.6 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source with an enhanced position: RA, Dec 97.3319,
-35.3717 which is equivalent to:
   RA(J2000)  = 06h 29m 19.66s
   Dec(J2000) = -35d 22' 18.0"
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.  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 (8.88 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 6.5
(+5.28/-4.30) x 10^21 cm^-2 (90% confidence). 

The initial flux in the 2.5 s image was 3.52e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 90 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers none of
the XRT error circle. The 8'x8' region for the list of sources generated
on-board covers 100% of the XRT error circle. The list of sources is typically
complete to about 18 mag. No correction has been made for the expected
extinction corresponding to E(B-V) of 0.076. 

Burst Advocate for this burst is B. Sbarufatti (bxs60 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: GRB210704A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30451
SUBJECT: GRB 210704A: Lowell Discovery Telescope Optical Observations
DATE:    21/07/12 13:02:36 GMT
FROM:    Brendan O'Connor at UMD  <oconnorb@umd.edu>

B. O'Connor (GWU, UMD), E. Troja (UMD, NASA-GSFC), E. Zack (UMD),
S.Dichiara (UMD, NASA-GSFC), P. Gatkine (Caltech), J.M. Durbak (UMD),
S.B. Cenko (NASA-GSFC), A. Kutyrev (UMD, NASA-GSFC), S. Veilleux (UMD)
report:

We observed the field of GRB 210704A (Ursi et al., GCN 30372;
Berretta et al., GCN 30375; Prasad et al., GCN 30378; D'Ai et al.,
GCN 30379; Malacaria et al., GCN 30380; Ridnaia et al., GCN 30388)
with the Large Monolithic Imager (LMI) on the 4.3m Lowell Discovery
Telescope (LDT) at Happy Jack, AZ. Observations started on July 11, 2021
at 3:57:51 UT (about 6.4 days after the GRB trigger) in the SDSS r filter.
The observations were taken at airmass 1.8 and seeing 2.0" for 1500 s.

We detect the optical afterglow (Kim et al., GCN 30384)
with magnitude r ~ 23.4 +/- 0.2 AB mag. This indicates a
negligible decay of the transient between 4.1 and 6.4 days
(Watson et al., GCN 30436).

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

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


GRB_name: GRB210704A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30452
SUBJECT: GRB 210704A: classification as long GRB and redshift estimating
DATE:    21/07/12 13:07:08 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

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

We analyzed GRB 210704A (Ursi et al., GCN 30372; Berretta et al., GCN 
30375; Prasad et al., GCN 30378; D'Ai et al., GCN 30379; Malacaria 
etal., GCN 30380; Ridnaia et al., GCN 30388) using publicly available 
data of GBM/Fermi. The burst consists of several episodes of emission 
with duration of T_90 = 4.6 s, but the emission is visible up to 20 s 
after the trigger. Energy spectrum constructed in the time interval of 
(-0.2, 6.5) seconds relative to the GBM trigger time is best described 
by Bandmodel with relatively low E_peak = 294 keV corroborating with 
E_peak reported by GBM team (Malacaria et al., GCN 30380) and Konus-Wind 
(Ridnaia et al., GCN 30388).

Based on E_peak, Fluence in 1 keV â€” 10 MeV range (2.77e-5 erg cm^-2) and 
T_90 we draw a trajectory of the burst in EH - T_90 diagram varying the 
unknown source redshift 
(http://grb.rssi.ru/GRB210704A/GRB210704A_EH-T90_GBM.png , see [1-2] for 
details). The lower 2 sigma redshift limit of the source is z=0.11, 
which excludes the association of the GRB with the field galaxy at z = 
0.0817, but leaves a possibility of association with the field cluster 
at z = 0.203 (de Ugarte Postigo et al., GCN 30392). We also estimate 
E_iso = 8.2e50 erg at z = 0.11 and E_iso = 3.7e53 erg at z = 2.34 
(marginally suggested after GTC spectroscopy, de Ugarte Postigo et al., 
GCN 30392).
Based only on the trajectory at the EH - T_90 diagram we could suggest 
the collapsar origin (Type II) of GRB 210704A.

[1] - Minaev et al., MNRAS, 492, 1919, 2020
[2] - Minaev et al., Astronomy Letters, 46, 9, 573, 2020


GRB_name: GRB210712A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30453
SUBJECT: GRB 210712A: Enhanced Swift-XRT position
DATE:    21/07/12 18:32:40 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.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 1702 s of XRT Photon Counting mode data and 4 UVOT
images for GRB 210712A, 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 = 97.33177, -35.37165 which is equivalent
to:

RA (J2000): 06h 29m 19.63s
Dec (J2000): -35d 22' 18.0"

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: GRB210712A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30455
SUBJECT: GRB 210712A: BOOTES-3/YA optical upper limit
DATE:    21/07/12 21:08:42 GMT
FROM:    Youdong HU at IAA-CSIC  <huyoudong072@hotmail.com>

Y.-D. Hu, E. Fernandez-Garcia, T.-R. Sun, A. J. Castro-Tirado, M. D. Caballero-Garcia, M. A. Castro Tirado (IAA-CSIC), I. Carrasco and C. Perez del Pulgar (Univ. de Malaga), and R. Querel (NIWA), on behalf of a larger collaboration, report:

The 60cm BOOTES-3/YA robotic telescope at NIWA Lauder in Otago (New Zealand) automatically responded to the Swift trigger of GRB 210712A (Sbarufatti et al. GCNC 30447). Images were taken starting at 15:01 UT, but due to poor weather conditions, only images taken after 17:32 UT (~7.8 hrs after trigger) could be used. In the co-added image (30 exposures 60s each), no source is found at the position reported by Swift/XRT (Evans et al. GCNC 30453) down to 19.6 mag which is consistent with the non-detection by Swift/UVOT (Sbarufatti et al. GCNC 30447). Further observations are ongoing.

We thank the staff at NIWA for its excellent support.


GRB_name: GRB210712A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30456
SUBJECT: GRB 210712A: Swift/UVOT Upper Limits
DATE:    21/07/12 23:12:07 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <mhs18@psu.edu>

M. H. Siegel (PSU) and B. Sbarufatti (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210712A
91 s after the BAT trigger (Sbarufatti et al., GCN Circ. 30447).
No optical afterglow consistent with the enhanced XRT position
(Evans et al. GCN Circ. 30453) 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            91          241          147         >19.5
u_FC               304          554          246         >19.6
white               91          604          167         >19.5
b                  560          579           19         >18.0
u                  304          554          246         >19.6
w2                 609          614            4         >17.5

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.076 in the direction of the burst
(Schlegel et al. 1998).


