GRB 251103A
GCN Circular 42579
Subject
GRB 251103A: Optical afterglow detection by ZTF’s public survey
Date
2025-11-04T15:14:43Z (7 hours ago)
From
Amaliya Atamalibekova <aa2569@cornell.edu>
Via
Web form
A. Atamalibekova and A. Y. Q. Ho (Cornell)
We report a serendipitous detection of the optical afterglow to GRB 251103A (Hu et al., GCN 42534, Schneider et al., GCN Circ. 42535; Turpin et al., GCN Circ. 42538; Gritsevich et al., GCN Circ. 42539; Izzo et al., GCN Circ. 42540, O'Neill et al., GCN Circ. 42543, Ghosh et al., GCN Circ. 42545, A. A. Breeveld et al., GCN Circ. 42554, R. Hellot et al., GCN Circ. 42559) by the Zwicky Transient Facility Public Survey. The transient ZTF25accpzjo was detected on 2025-11-03 22:39 UTC at g=19.76 +/- 0.21 mag, and two hours later at r = 19.24 +/- 0.11 mag. The last upper limit was two days prior, at 2025-11-01 23:56 UTC (g > 21.10 mag from forced photometry). The combination of fast rise (0.67 mag/day) and red colors g-r = 0.47 +/- 0.23 (corrected for Milky Way extinction) was flagged by a pipeline for discovering afterglows in the ZTF data (e.g. Ho et al. 2020, ApJ, 905, 98). Upon a retrospective search, we identified ZTF25accpzjo as the afterglow to GRB 251103A.
GCN Circular 42577
Subject
GRB 251103A: WFST optical observations
Date
2025-11-04T13:13:47Z (9 hours ago)
From
ylhua@pmo.ac.cn
Via
Web form
Yan-Long Hua, Chao Wu (NAOC), Jin-Jun Geng, Xue-Feng Wu, Jun-Jie Wei, Tian-Rui Sun, Yi-Fang Liang, Ding-Fang Hu, Guan-Xiao Li, Yuan-Tai Yang, Jia-Zheng Zhu, Ze-Lin Xu, Ning Jiang, Ji-An Jiang report on behalf of the WFST team:
Following the detection of GRB 251103A by SVOM(Hu et al., GCN 42534，Benjamin Schneider et al., GCN 42549,Chen-Wei Wang et al., GCN 42552), Fermi/GBM (Fermi GBM Team, GCN 42536, GCN 42553), Swift (J.P. Osborne et al., GCN 42551,A. A. Breeveld et al., GCN 42554).
We performed follow-up observations using the Wide Field Survey Telescope (WFST Collaboration; arXiv:2306.07590) at the Lenghu Astronomical Observation Base in Qinghai Province, China. Observations in the r/g band began at 2025-11-03T20:57:29 UTC, approximately 16 hours after the trigger.
The afterglow is detected in r/g band we measured the following preliminary magnitude:
r = 20.82 +/- 0.16,2025-11-03T20:59:45 UTC
g = 21.10 +/- 0.12,2025-11-03T22:30:38 UTC
The photometric calibration was performed using nearby stars from the PanSTARRS catalog is in the AB system, and is not corrected for Galactic extinction.
We thank the WFST staff for supporting these observations.
GCN Circular 42574
Subject
GRB 251103A: OHP/T193 optical observations
Date
2025-11-04T11:29:23Z (11 hours ago)
From
Christophe Adami at LAM <christophe.adami@lam.fr>
Via
Web form
C. Adami (LAM/Pytheas/AMU), N.A. Rakotondrainibe (LAM), B. Schneider (LAM), S. Basa (UAR Pytheas), E. Le Floc'h (CEA/Irfu) report on behalf of the MISTRAL GRB collaboration:
We carried out observations of the GRB 251103A (Hu et al., GCN 42534, Schneider et al., GCN 42535; Fermi GBM Team, GCN 42536; Turpin et al., GCN 42538; Gritsevich et al., GCN 42539, Izzo et al., GCN 42540; Osborne et al., GCN 42551; O'Neill et al., GCN 42543; Ghosh et al., GCN 42545; Schneider et al., GCN 42549; Osborne et al., GCN 42551; Wang et al., GCN 42552; Sonawane et al., GCN 42553; Breeveld et al., GCN 42554; Hellot et al., GCN 42559; Mo et al., GCN 42562; Lipunov et al., GCN 42565; Delaunay et al., GCN 42568; Zheng et al., GCN 42571, Ren et al., GCN 42572) using the T193cm telescope at Observatoire de Haute-Provence (France) equipped with the MISTRAL spectro-imager. We obtained 94 min (1 exposure of 4 min and 18 exposures of 5 min) in the r-band at a midtime of 2025-11-04 05:24:03 UT corresponding to T-T0 = 24.63 hours.
The afterglow is detected in r’ and we measured the following preliminary magnitude:
r’ = 22.33 +/- 0.16
The photometric calibration was performed using nearby stars from the PanSTARRS catalog and the STDWeb/STDPipe tools (Karpov 2025), is in the AB system, and is not corrected for Galactic extinction.
We acknowledge the excellent support from the Observatoire de Haute-Provence and in particular Yoann Degot-Longhi.
GCN Circular 42573
Subject
GRB 251103A: Xinglong 2.16m optical detection
Date
2025-11-04T11:27:31Z (11 hours ago)
From
Youdong HU at GXU <huyoudong072@hotmail.com>
Via
Web form
L. P. Xin (NAOC), Y.-D. Hu, X. Tian (GXU), Y. Zhang, J. Wang, J.-Y. Wei (NAOC) report on behalf of SVOM follow-up team:
We observed the field of GRB 251103A (Hu et al., GCN 42534; Fermi GBM Team, GCN 42536; Wang et al., GCN 42552; Sonawane et al., GCN 42553; DeLaunay et al., GCN 42568; Ren et al., GCN 42572). using the 2.16-m telescope located at Xinglong observatory, China, equipped with the BFOSC camera. We obtained 9*200s frames in R-band, starting at 21:11:22 UT on 2025-11-03, about 16.7 hrs after the trigger.
The optical afterglow (Schneider et al., GCN 42535; Turpin et al., GCN 42538; Gritsevich et al., GCN 42539; Izzo et al., GCN 42540; O'Neill et al., GCN 42543; Ghosh et al., GCN 42545; Schneider et al., GCN 42549; Breeveld et al., GCN 42554; Hellot et al., GCN 42559; Mo et al., GCN 42562; Zheng et al., GCN 42571) was clearly detected in the stacked image with a magnitude of R=20.78+-0.08 mag at the mid time, which calibrate with nearby SDSS stars.
We thank the staff at Xinglong observatory for their excellent support.
GCN Circular 42572
Subject
GRB 251103A: Insight-HXMT detection
Date
2025-11-04T10:49:35Z (11 hours ago)
From
renyz16607@163.com
Via
Web form
GRB 251103A: Insight-HXMT detection
Yang-Zhao Ren, Chen-Wei Wang, Cheng-Kui Li, Shao-Lin Xiong, and Chao Zheng report on behalf of the Insight-HXMT team:
At 2025-11-03T04:46:28.000 (T0), Insight-HXMT/HE detected the burst GRB 251103A, which is also detected by SVOM/ECLAIRs (Hu et al., GCN#42534), Fermi/GBM (Fermi GBM team, GCN #42536), SVOM/GRM (Wang et al., GCN#42552).
The Insight-HXMT/HE light curve mainly consists of a single pulse with a T90 of 5.5 +2.5/-2.0 s. The 1s peak rate, measured from T0+0.25 s, is 2447 cnts/sec. The total counts from this burst is 5414 counts.
The HXMT/HE light curve can be found here:
https://www.bursthub.cn//admin/static/hxmtgrb251103A.png
All measurements above are made with the CsI detectors operating in the regular mode with the energy range of about 60-900 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
GCN Circular 42571
Subject
GRB 251103A: KAIT optical observations
Date
2025-11-04T08:07:10Z (14 hours ago)
From
Weikang Zheng at UC Berkeley <weikang@berkeley.edu>
Via
email
WeiKang Zheng (UCB), Xuhui Han (NAOC), Pinpin Zhang (NAOC) and
Alexei V. Filippenko (UCB) report on behalf of the KAIT GRB team:
The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, observed the field of GRB 251103A (Hu et al.,
GCN 42534; Fermi GBM Team, GCN 42536; Wang et al., GCN 42552;
Sonawane et al., GCN 42553; DeLaunay et al., GCN 42568) starting
at 11:54 UT, 7.13 hours after the burst. A set of clear (roughly R)
filter images were obtained. We clearly detected the afterglow
(Schneider et al., GCN 42535; Turpin et al., GCN 42538; Gritsevich
et al., GCN 42539; Izzo et al., GCN 42540; O'Neill et al., GCN 42543;
Ghosh et al., GCN 42545; Schneider et al., GCN 42549; Breeveld et al.,
GCN 42554; Hellot et al., GCN 42559; Mo et al., GCN 42562) in our
coadd image. We measure its brightness to be 19.4 +/- 0.2 mag (Vega)
at mid time of 7.72 hours after the burst.
GCN Circular 42568
Subject
GRB 251103A: Swift/BAT-GUANO arcminute localization of a burst
Date
2025-11-04T03:36:10Z (19 hours ago)
From
Jimmy DeLaunay at Penn State <delauj2@gmail.com>
Via
Web form
James DeLaunay (PSU), Aaron Tohuvavohu (Cosmic Frontier), Samuele Ronchini (GSSI), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC), Maia Williams (Northwestern) report:
Swift/BAT did not localize GRB 251103A onboard (T0: 2025-11-03T04:46:28.11 UTC, Fermi Trig 783837993, SVOM Trig sb25110301).
The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1).
Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground.
The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), detects the burst in a 2.048 s analysis time bin starting at T0 - 0.0 s with a sqrt(TS) of 61.6.
An arcminute localization is found with DeltaLLHOut of 24 and a DeltaLLHPeak of 10.2.
See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descriptions and interpretations of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut.
The BAT position is
RA, Dec = 146.821, 16.104 deg which is
RA(J2000) = 09h 47m 17.04s
Dec(J2000) = 16d 06’ 14.4″
with an estimated uncertainty of 5 arcmin radius.
More details about this burst can be found on the trigger report page here:
https://guano.swift.psu.edu/trigger_report?id=783838024
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/
GCN Circular 42565
Subject
Fermi GRB 251103A: Global MASTER-Net observations report
Date
2025-11-03T23:31:13Z (a day ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
email
V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko,
G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU),
O.Gress, N.Budnev (ISU),
C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A.Sosnovskij (CrAO),
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity),
D.Buckley (SAAO),
R.Rebolo (The Instituto de Astrofisica de Canarias),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory)
MASTER-Tavrida robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, SAI Crimea astronomical station) started inspect of the Fermi GRB 251103A ( Fermi GBM team, GCN 42536) errorbox 63596 sec after notice time and 63634 sec after trigger time at 2025-11-03 22:27:02 UT, with upper limit up to 17.2 mag. The observations began at zenith distance = 77 deg. The sun altitude is -58.5 deg.
MASTER-Kislovodsk robotic telescope located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 251103A errorbox 65141 sec after notice time and 65180 sec after trigger time at 2025-11-03 22:52:48 UT, with upper limit up to 16.8 mag. The observations began at zenith distance = 70 deg. The sun altitude is -52.4 deg.
The galactic latitude b = 48 deg., longitude l = 216 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=3030951
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
63665 | 2025-11-03 22:27:02 | MASTER-Tavrida | (09h 39m 04.69s , +19d 28m 36.2s) | C | 60 | 15.8 |
63743 | 2025-11-03 22:28:21 | MASTER-Tavrida | (09h 45m 39.49s , +18d 09m 40.8s) | C | 60 | 15.6 |
63812 | 2025-11-03 22:29:30 | MASTER-Tavrida | (09h 50m 09.05s , +19d 26m 40.9s) | C | 60 | 15.9 |
63890 | 2025-11-03 22:30:48 | MASTER-Tavrida | (09h 43m 57.72s , +20d 45m 36.4s) | C | 60 | 15.8 |
63957 | 2025-11-03 22:31:54 | MASTER-Tavrida | (09h 34m 46.40s , +18d 09m 53.8s) | C | 60 | 14.9 |
64037 | 2025-11-03 22:33:15 | MASTER-Tavrida | (09h 47m 09.24s , +16d 23m 55.5s) | C | 60 | 15.6 |
64112 | 2025-11-03 22:34:29 | MASTER-Tavrida | (09h 41m 40.15s , +16d 50m 37.4s) | C | 60 | 15.8 |
64187 | 2025-11-03 22:35:45 | MASTER-Tavrida | (09h 54m 59.68s , +20d 46m 42.7s) | C | 60 | 15.6 |
64264 | 2025-11-03 22:37:02 | MASTER-Tavrida | (09h 49m 01.38s , +22d 03m 37.6s) | C | 60 | 16.1 |
64429 | 2025-11-03 22:39:47 | MASTER-Tavrida | (09h 37m 53.16s , +15d 32m 17.9s) | C | 60 | 16.0 |
64597 | 2025-11-03 22:42:34 | MASTER-Tavrida | (09h 52m 28.41s , +16d 52m 15.0s) | C | 60 | 16.0 |
64665 | 2025-11-03 22:43:42 | MASTER-Tavrida | (09h 56m 36.54s , +18d 09m 42.0s) | C | 60 | 15.9 |
64740 | 2025-11-03 22:44:58 | MASTER-Tavrida | (09h 48m 39.02s , +15d 32m 54.2s) | C | 60 | 15.9 |
64817 | 2025-11-03 22:46:15 | MASTER-Tavrida | (10h 01m 15.68s , +19d 27m 16.3s) | C | 60 | 15.9 |
64896 | 2025-11-03 22:47:34 | MASTER-Tavrida | (09h 32m 51.01s , +20d 44m 10.5s) | C | 60 | 15.9 |
65080 | 2025-11-03 22:50:38 | MASTER-Tavrida | (09h 30m 39.62s , +16d 50m 15.8s) | C | 60 | 16.2 |
65210 | 2025-11-03 22:52:48 | MASTER-Kislovodsk | (09h 45m 41.10s , +15d 52m 44.3s) | C | 60 | 15.3 |
65210 | 2025-11-03 22:52:48 | MASTER-Kislovodsk | (09h 45m 37.84s , +16d 14m 48.4s) | C | 60 | 15.3 |
65252 | 2025-11-03 22:53:30 | MASTER-Tavrida | (09h 28m 08.59s , +19d 27m 24.4s) | C | 60 | 16.0 |
65290 | 2025-11-03 22:54:08 | MASTER-Kislovodsk | (09h 45m 42.17s , +15d 53m 49.3s) | C | 60 | 15.3 |
65290 | 2025-11-03 22:54:08 | MASTER-Kislovodsk | (09h 45m 38.78s , +16d 15m 52.2s) | C | 60 | 15.2 |
65329 | 2025-11-03 22:54:47 | MASTER-Tavrida | (10h 03m 23.21s , +16d 50m 53.3s) | C | 60 | 16.0 |
65370 | 2025-11-03 22:55:27 | MASTER-Kislovodsk | (09h 45m 44.69s , +16d 14m 55.7s) | C | 60 | 14.4 |
65407 | 2025-11-03 22:56:04 | MASTER-Tavrida | (09h 59m 28.09s , +15d 33m 03.1s) | C | 60 | 16.1 |
65450 | 2025-11-03 22:56:47 | MASTER-Kislovodsk | (09h 45m 37.64s , +16d 14m 01.1s) | C | 60 | 13.0 |
65492 | 2025-11-03 22:57:30 | MASTER-Tavrida | (09h 45m 09.73s , +14d 16m 08.9s) | C | 60 | 16.0 |
65572 | 2025-11-03 22:58:49 | MASTER-Tavrida | (09h 43m 15.43s , +23d 20m 25.8s) | C | 60 | 15.9 |
65652 | 2025-11-03 23:00:09 | MASTER-Tavrida | (09h 23m 45.21s , +18d 09m 40.8s) | C | 60 | 16.3 |
65719 | 2025-11-03 23:00:47 | MASTER-Kislovodsk | (09h 45m 40.53s , +16d 14m 40.7s) | C | 120 | 12.0 |
65732 | 2025-11-03 23:01:29 | MASTER-Tavrida | (09h 55m 49.49s , +14d 15m 39.6s) | C | 60 | 16.1 |
65813 | 2025-11-03 23:02:51 | MASTER-Tavrida | (10h 07m 38.94s , +18d 09m 58.4s) | C | 60 | 15.8 |
65859 | 2025-11-03 23:03:06 | MASTER-Kislovodsk | (09h 45m 43.46s , +16d 16m 15.9s) | C | 120 | 13.2 |
65998 | 2025-11-03 23:05:26 | MASTER-Kislovodsk | (09h 45m 42.35s , +15d 53m 35.0s) | C | 120 | 13.1 |
65998 | 2025-11-03 23:05:26 | MASTER-Kislovodsk | (09h 45m 38.38s , +16d 15m 33.9s) | C | 120 | 13.8 |
66058 | 2025-11-03 23:05:26 | MASTER-Kislovodsk | (09h 45m 38.38s , +16d 15m 33.9s) | C | 240 | 14.9 | Coadd
65983 | 2025-11-03 23:05:41 | MASTER-Tavrida | (10h 00m 15.07s , +22d 04m 18.9s) | C | 60 | 15.7 |
66063 | 2025-11-03 23:07:01 | MASTER-Tavrida | (09h 34m 27.78s , +14d 15m 40.9s) | C | 60 | 15.2 |
66108 | 2025-11-03 23:07:46 | MASTER-Kislovodsk | (09h 45m 38.40s , +16d 16m 40.2s) | C | 60 | 14.3 |
66143 | 2025-11-03 23:08:21 | MASTER-Tavrida | (10h 06m 05.12s , +20d 46m 52.5s) | C | 60 | 14.8 |
66188 | 2025-11-03 23:09:05 | MASTER-Kislovodsk | (09h 45m 44.30s , +16d 15m 44.3s) | C | 60 | 14.6 |
66268 | 2025-11-03 23:10:25 | MASTER-Kislovodsk | (09h 45m 37.28s , +16d 14m 49.5s) | C | 60 | 15.0 |
66328 | 2025-11-03 23:10:25 | MASTER-Kislovodsk | (09h 45m 37.28s , +16d 14m 49.4s) | C | 180 | 16.6 | Coadd
66322 | 2025-11-03 23:11:19 | MASTER-Tavrida | (09h 27m 05.34s , +15d 31m 34.4s) | C | 60 | 16.1 |
66676 | 2025-11-03 23:17:14 | MASTER-Kislovodsk | (09h 45m 43.23s , +16d 16m 03.7s) | C | 60 | 16.3 |
66676 | 2025-11-03 23:17:14 | MASTER-Kislovodsk | (09h 45m 50.89s , +15d 54m 01.9s) | C | 60 | 16.5 |
66708 | 2025-11-03 23:17:45 | MASTER-Tavrida | (09h 26m 34.95s , +22d 02m 43.8s) | C | 60 | 16.9 |
66756 | 2025-11-03 23:18:34 | MASTER-Kislovodsk | (09h 45m 46.97s , +15d 55m 46.6s) | C | 60 | 16.7 |
66756 | 2025-11-03 23:18:34 | MASTER-Kislovodsk | (09h 45m 39.21s , +16d 17m 48.1s) | C | 60 | 16.3 |
66789 | 2025-11-03 23:19:07 | MASTER-Tavrida | (09h 54m 31.91s , +23d 22m 17.1s) | C | 60 | 17.1 |
66836 | 2025-11-03 23:19:54 | MASTER-Kislovodsk | (09h 45m 46.98s , +15d 53m 57.9s) | C | 60 | 16.7 |
66836 | 2025-11-03 23:19:54 | MASTER-Kislovodsk | (09h 45m 39.10s , +16d 15m 58.7s) | C | 60 | 16.3 |
66896 | 2025-11-03 23:19:54 | MASTER-Kislovodsk | (09h 45m 39.10s , +16d 15m 58.7s) | C | 180 | 16.8 | Coadd
66917 | 2025-11-03 23:21:14 | MASTER-Kislovodsk | (09h 45m 51.06s , +15d 55m 42.0s) | C | 60 | 16.8 |
66917 | 2025-11-03 23:21:14 | MASTER-Kislovodsk | (09h 45m 43.07s , +16d 17m 42.5s) | C | 60 | 16.5 |
66968 | 2025-11-03 23:22:05 | MASTER-Tavrida | (09h 31m 55.01s , +23d 19m 40.3s) | C | 60 | 17.2 |
66996 | 2025-11-03 23:22:34 | MASTER-Kislovodsk | (09h 45m 45.14s , +15d 55m 04.0s) | C | 60 | 16.3 |
66996 | 2025-11-03 23:22:34 | MASTER-Kislovodsk | (09h 45m 37.01s , +16d 17m 04.4s) | C | 60 | 16.1 |
67076 | 2025-11-03 23:23:54 | MASTER-Kislovodsk | (09h 45m 45.15s , +15d 56m 08.7s) | C | 60 | 16.6 |
67076 | 2025-11-03 23:23:54 | MASTER-Kislovodsk | (09h 45m 36.92s , +16d 18m 08.8s) | C | 60 | 16.3 |
67157 | 2025-11-03 23:25:14 | MASTER-Kislovodsk | (09h 45m 41.84s , +16d 17m 11.6s) | C | 60 | 16.4 |
67157 | 2025-11-03 23:25:14 | MASTER-Kislovodsk | (09h 45m 50.18s , +15d 55m 11.6s) | C | 60 | 16.5 |
67237 | 2025-11-03 23:26:34 | MASTER-Kislovodsk | (09h 45m 35.80s , +16d 16m 16.3s) | C | 60 | 16.4 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 42562
Subject
GRB 251103A: J-band detection with WINTER
Date
2025-11-03T22:00:37Z (a day ago)
From
Geoffrey Mo at Caltech / Carnegie Observatories <gmo@mit.edu>
Via
Web form
Geoffrey Mo (Caltech/Carnegie), Benjamin Schneider (LAM), Tomas Ahumada (Caltech), Viraj Karambelkar (Columbia), Robert Stein (UMD), Danielle Frostig (CfA), Nathan Lourie (MIT), Robert Simcoe (MIT), and Mansi Kasliwal (Caltech) report:
We observed the field of GRB 251103A (Hu et al., GCN 42534, Fermi GBM Team, GCN 42536; Osborne et al., GCN 42551; Wang et al., GCN 42552; Sonawane et al., GCN 42553) in the near-infrared J band with the Palomar 1-m telescope, equipped with the 1.2-square degree WINTER camera (Lourie et al. 2020, Frostig et al. 2024).
Two epochs of observations were performed in the J band, beginning at 2025-11-03T10:02 UTC (+5.3 hours after the GRB trigger) and at 2025-11-03T11:39:53 UTC (+6.9 hours), each consisting of 15 x 120 s exposures. The images were processed using the WINTER data reduction pipeline implemented with mirar (https://github.com/winter-telescope/mirar, https://doi.org/10.5281/zenodo.13352565).
We detect a source at the optical counterpart location (Schneider et al., GCN 42535; Turpin et al., GCN 42538; Gritsevich et al., GCN 42539; Izzo et al., GCN 42540; O'Neill et al., GCN 42543; Ghosh et al., GCN 42545; Schneider et al., GCN 42549; Breeveld et al., GCN 42554; Hellot et al., GCN 42559) in the first epoch, with magnitude J ~ 19.4 mag (AB). In the second epoch, we set a 3-sigma upper limit of J ~ 19.7 mag (AB) and a 5-sigma upper limit of J ~ 19.3 mag (AB).
WINTER (Wide-field INfrared Transient ExploreR) is a partnership between MIT and Caltech, housed at Palomar Observatory, and funded by NSF MRI, NSF AAG, the David and Lucile Packard Foundation, and the MIT Kavli Institute for Astrophysics and Space Research.
GCN Circular 42559
Subject
GRB 251103A: Kilonova-Catcher optical afterglow detection
Date
2025-11-03T21:17:21Z (a day ago)
From
Damien Turpin at CEA-Saclay <dturpin-astro@hotmail.com>
Via
Web form
R. Hellot, M. Freeberg (KNC), D. Turpin (CEA-Saclay/Irfu), C. Andrade(UMN), S. Antier (OCA/IJCLab), M. Coughlin (UMN), S. Karpov (FZU), P. Hello (IJCLAB), M. Pillas (IAP) on behalf of the GRANDMA/Kilonova-Catcher collaboration:
We observed the field of GRB 251103A detected by SVOM (Hu et al., GCN 42534; Wang et al., GCN 42552) and Fermi/GBM (Fermi GBM team GCN 45536) with the GRANDMA citizen science project Kilonova-catcher (KNC). Our observations were performed with a TEC160FL telescope operated by M. Freeberg and a CDK17 telescope located at AITP San Pedro Chile Observatory operated by R. Hellot. Our observations started at TGRB+3.2hr and were taken with sdss ri filters.
In our stacked frames, subtracted from the PanSTARRS DR2 template image, we detect the optical counterpart reported by the NOT (Schneider et al., GCN 42535), LCOGT/1m (Turpin et al., GCN 42538; Ghosh et al., GCN 42545), BOOTES-2/TELMA (Gritsevich et al., GCN 42539), GOTO (O'Neill et al., GCN 42543), SVOM/COLIBRÍ (FM-GFT) (Schneider et al., GCN 42549), Swift/UVOT (Breeveld et al., GCN 42554).
We report part of our follow-up results in the table below:
+---------------+-----------+--------+----------------+--------------+
| Tmid-TGRB (hr)| Exp (s) | Filter | Magnitude | Instrument |
+===============+===========+========+================+==============+
| 3.62 | 10 x 180s | r (AB) | 18.66 +/- 0.06 | CDK17 AITP |
| 4.89 | 10 x 180s | r (AB) | 19.02 +/- 0.12 | TEC160FL |
| 5.46 | 10 x 180s | i (AB) | 19.33 +/- 0.28 | TEC160FL |
+---------------+-----------+--------+----------------+--------------+
All the data have been reduced by a single data processing pipeline, STDPipe (Karpov et al., 2022). Images obtained with the sloan filters were calibrated using the PanSTARRS DR1 catalog.
We use the SkyPortal application (skyportal.io) to monitor our observational campaign (Coughlin et al. 2023).
GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is the citizen science program of GRANDMA (http://kilonovacatcher.in2p3.fr/).
GCN Circular 42554
Subject
GRB 251103A: Swift/UVOT Detection
Date
2025-11-03T16:40:07Z (a day ago)
From
Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>
Via
email
A. A. Breeveld (UCL-MSSL) and S. Lanava (PSU) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of the SVOM/ECLAIRs detected burst GRB 251103A 4797s after the trigger (Hu et al., GCN Circ. 42534).
The optical counterpart detected by Schneider et al., GCN Circ. 42535; Turpin et al., GCN Circ. 42538; Gritsevich et al., GCN Circ. 42539; Izzo et al., GCN Circ. 42540, O'Neill et al., GCN Circ. 42543, Ghosh et al., GCN Circ. 42545, is detected in the initial U-band UVOT exposures, and is fading.
Preliminary magnitudes 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
u 4797 6349 1528 17.3 ± 0.04
u 9974 10188 211 17.9 ± 0.10
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.061 in the direction of the burst (Schlegel et al. 1998).
GCN Circular 42553
Subject
GRB 251103A: Fermi GBM Observation
Date
2025-11-03T16:33:54Z (a day ago)
From
Rushikesh Sonawane at IISER, TVM <rushikesh23@iisertvm.ac.in>
Via
Web form
R. Sonawane (IISER, TVM) and M. Godwin (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:
"At 04:46:28.11 UT on 03 November 2025, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 251103A (trigger 783837993/251103199),
which was also detected by SVOM/ECLAIRs (Hu et al. 2025, GCN 42534).
The Fermi GBM on-ground location is consistent with the SVOM/ECLAIRs position.
NOT measured a spectroscopic redshift z = 0.76 (Izzo et al. 2025, GCN 42540).
The angle from the Fermi LAT boresight is 113 degrees.
The GBM light curve consists of a single emission episode with a duration (T90)
of about 4 s (50-300 keV). The time-averaged spectrum
from T0-3.0 to T0+6.2 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -0.42 +/- 0.03 and the cutoff energy,
parameterized as Epeak, is 151 +/- 3 keV.
The event fluence (10-1000 keV) in this time interval is
(5.6 +/- 0.4)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.13 s in the 10-1000 keV band is 18.8 +/- 0.5 ph/s/cm^2.
A Band function fits the spectrum equally well
with Epeak= 123 +/- 2 keV, alpha = -0.18 +/- 0.01 and beta = -2.4 +/- 0.1.
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/"
GCN Circular 42552
Subject
GRB 251103A: SVOM/GRM observation
Date
2025-11-03T15:34:46Z (a day ago)
From
Chenwei Wang at IHEP <cwwang@ihep.ac.cn>
Via
Web form
SVOM/GRM team: Chen-Wei Wang. Xing-Hao Luo, Yue Huang, Shi-Jie Zheng, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: Ulysse Jacob (LUPM)
Report on behalf of the SVOM team:
SVOM/GRM was triggered in-flight by a burst GRB 251103A (SVOM trigger reference: sb25110302) at 2025-11-03T04:46:28.000 UTC (T0), which is also detected by SVOM/ECLAIRs (Hu et al., GCN#42534) and Fermi/GBM (Fermi GBM Team, GCN#42536).
With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a single pulse with a T90 of 8.6 +0.8/-0.8 s in the 15-5000 keV band.
The SVOM/GRM light curve can be found here:
https://www.bursthub.cn//admin/static/svgrb251103A.png
In addition, the position of this burst, as determined by SVOM/ECLAIRs (RA= 146.8375, DEC= 16.1296, GCN#42534), is located at about 13 degrees from the SVOM optical axis.
With this localization, the time-averaged spectrum from T0-2 to T0+7 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.21 +0.06/-0.05 and the cutoff energy, parameterized as Epeak, is 185 +23/-18 keV. The event fluence (10-1000 keV) in this time interval is (8.18 +0.41/-0.38)E-06 erg/cm^2.
The 1s peak spectrum, measured from T0+0.2 to T0+1.2 s, is also best fitted by a power law function with an exponential high-energy cutoff. The power law index is -0.89 +0.06/-0.06 and the cutoff energy, parameterized as Epeak, is 198 +15/-13 keV. The flux (10-1000 keV) in this time interval is (2.61 +0.11/-0.10)E-06 erg/cm^2/s.
Assuming the redshift z=0.76 (L. Izzo et al., GCN#42540), the localization of GRB 251103A in the 'Amati' relation diagram is shown at:
https://www.bursthub.cn//admin/static/svgrb251103A_amati.png
And the localization in the 'Yonetoku' relation diagram is shown at:
https://www.bursthub.cn//admin/static/svgrb251103A_yonetoku.png
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS.
The SVOM point of contact for this burst is: Chen-Wei Wang (IHEP)(cwwang@ihep.ac.cn)
GCN Circular 42551
Subject
GRB 251103A: Swift-XRT afterglow detection
Date
2025-11-03T15:18:01Z (a day ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
J.P. Osborne (U. Leicester), M. Ferro (INAF-OAB), R. Brivio (INAF-OAB),
A. D'Ai (INAF-IASFPA), S. Lanava (PSU), S. Dichiara (PSU), J.A. Kennea
(PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester) and P.A.
Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of GRB 251103A (Hu et
al., GCN Circ. 42534). We searched for X-ray sources in 1.6 ks of
Photon Counting (PC) mode data. The total exposure at the position of
the afterglow (see below) is 1.6 ks, obtained between T0+4.8 ks and
T0+10.2 ks.
An uncatalogued X-ray source is detected within the estimated 3-sigma
SVOM/ECLAIRs error region (210 arcsec) and is above the LSXPS 3-sigma
upper limit at this position, and is therefore likely the GRB
afterglow. Using 1768 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 = 146.83866, +16.12272
which is equivalent to:
RA (J2000): 09h 47m 21.28s
Dec(J2000): +16d 07' 21.8"
with an uncertainty of 2.6 arcsec (radius, 90% confidence).
The source position is consistent with the one of the optical afterglow
reported by Schneider et al. (GCN Circ. 42535, 42549), Turpin et al.
(GCN Circ. 42538), Gritsevich et al. (GCN Circ. 42539), Izzo et al.
(GCN Circ. 42540), O'Neill et al. (GCN Circ. 42543) and Ghosh et al.
(GCN Circ. 42545).
The light curve can be modelled with a power-law decay with a decay
index of alpha=1.2 (+0.4, -0.3).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.82 (+0.16, -0.15). The
best-fitting absorption column is 9.9 (+4.7, -4.2) x 10^20 cm^-2, in
excess of the Galactic value of 4.0 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 3.8 x 10^-11 (4.4 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 9.9 (+4.7, -4.2) x 10^20 cm^-2
Galactic foreground: 4.0 x 10^20 cm^-2
Excess significance: 2.3 sigma
Photon index: 1.82 (+0.16, -0.15)
If the light curve continues to decay with a power-law decay index of
1.2, the count rate at T+24 hours will be 0.035 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.3 x
10^-12 (1.5 x 10^-12) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
https://www.swift.ac.uk/xrt_products/03000169.
The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/SVOM/SVOM_FIELD00047.
This circular is an official product of the Swift-XRT team.
GCN Circular 42549
Subject
GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations
Date
2025-11-03T13:42:39Z (a day ago)
From
Benjamin Schneider at MIT <bschn@mit.edu>
Via
Web form
Benjamin Schneider (LAM), Leonardo García García (UNAM), Stéphane Basa (UAR Pytheas), Jean-Grégoire Ducoin (CPPM), William H. Lee (UNAM), Alan M. Watson (UNAM), Fredd Alvarez (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Antonio de Ugarte Postigo (LAM), Y.-D. Hu (GXU) and X. Tian (GXU):
We imaged the field of the GRB 251103A (Hu et al., GCN Circ. 42534; Fermi GBM team, GCN 42536) using the DDRAGO wide-field imager on the SVOM/COLIBRÍ (FM-GFT) telescope. We observed from 2025-11-03T10:17:32 to 11:26:49 UTC (from 5.52 to 6.67 hr after the trigger) and obtained 16 minutes of exposure in the g, r, i, z, and y filters.
The data were reduced and coadded with the COLIBRÍ pipeline and analyzed with STDWeb/STDPipe (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction.
We detected the optical counterpart reported by Schneider et al., GCN Circ. 42535; Turpin et al., GCN Circ. 42538; Gritsevich et al., GCN Circ. 42539; Izzo et al., GCN Circ. 42540, O'Neill et al., GCN Circ. 42543, Ghosh et al., GCN Circ. 42545, at a preliminary magnitude of:
r = 19.48 +/- 0.04 (midtime = 6.04 hr)
z = 19.15 +/- 0.11 (midtime = 5.68 hr)
Compared to the early observations reported by Schneider et al. GCN Circ. 42535, we derive a temporal index of about -1.0 in the r-band.
Further observations are planned.
We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams.
COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico.
GCN Circular 42545
Subject
GRB 251103A: LCO optical observation
Date
2025-11-03T11:02:49Z (a day ago)
From
ankur ghosh at CAPP, University of Johannesburg <ghosh.ankur1994@gmail.com>
Via
Web form
Ankur Ghosh, Soebur Razzaque (CAPP, University of Johannesburg), Rahul Gupta (NASA GSFC), Alexander Moskvitin, Yulia Sotnikova (SAO RAS), Naveen Dukiya (ARIES) on behalf of a larger collaboration.
We observed the field of the GRB 251103A triggered by SVOM/ECLAIRs (Hu et al., GCN 42534) in V and r filters of the 1-meter Sinistro telescope at the Las Cumbres Observatory Global Telescope (LCOGT) node located at McDonald Observatory. The 1-m Sinistro telescope is equipped with a 4K x 4K CCD (FOV: 26 x 26 arcmin, scale: 0.39 arcsec/pixel).
Observations began on November 03, 2025, starting from 4.22 hours after the GRB trigger.
We clearly detect the optical transient (OT) reported by GCNs (Schneider et al., GCN 42535; Turpin et al., GCN 42538; Gritsevich et al., GCN 42539; Izzo et al., GCN 42540, O'Neill et al., GCN 42543) in our V and r band images.
|Date| |JD start| |t-T0 (hours)| |Exp (sec)| |Filter| |Magnitude|
-----------------------------------------------------------------------------------------------------
2025-11-03 2460982.90068 4.226 1 x 500 V V = 19.38 +/- 0.08
2025-11-03 2460982.90060 4.221 1 x 500 r r = 19.26 +/- 0.05
The field was calibrated against nearby APASS stars, with magnitudes converted using Lupton (2005) equations, and has not been corrected for Galactic extinction.
GCN Circular 42543
Subject
GRB 251103A: GOTO optical afterglow detection
Date
2025-11-03T09:46:24Z (2 days ago)
From
Sergey Belkin at Monash University <sergey.belkin@monash.edu>
Via
Web form
D. O'Neill, S. Belkin, B. P. Gompertz, G. Ramsay, R. Starling, K. Ackley, M. Dyer, J. Lyman, K. Ulaczyk, D. Steeghs, D. Galloway, V. Dhillon, P. O'Brien, K. Noysena, R. Kotak, R. Breton, J. Casares, L. Nuttall, B. Godson, T. Killestein, A. Kumar and M. Pursiainen report on behalf of the GOTO collaboration:
We report on optical observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022, Dyer et al. 2024) of GRB 251103A (Hu et al., GCN 42534; Fermi GBM Team, GCN 42536).
A serendipitous image from the all-sky survey was taken on Nov. 3 2025 06:15:34 UT (+1.5h post trigger). The observation consisted of 4x45s exposures in the GOTO L-band (400-700 nm). Images were processed immediately after acquisition using the GOTO pipeline. Difference imaging was performed using deeper template observations.
We detect the optical counterpart (Schneider et al., GCN 42535; Turpin et al., GCN 42538; Gritsevich et al., GCN 42539; Izzo et al., GCN 42540) with an AB magnitude of L = 17.81 ± 0.03.
Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and are not corrected for Galactic extinction.
GOTO (https://goto-observatory.org) is a network of telescopes that is principally funded by the STFC and operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester and the Instituto de Astrofisica de Canarias (IAC).
GCN Circular 42540
Subject
GRB 251103A: NOT spectroscopic redshift z = 0.76
Date
2025-11-03T06:51:49Z (2 days ago)
From
Benjamin Schneider at MIT <bschn@mit.edu>
Via
Web form
L. Izzo (INAF/OACN and DARK/NBI), D. B. Malesani (DAWN/NBI and Radboud), B. Schneider (LAM), A. Saccardi (CEA/Irfu), A. de Ugarte Postigo (LAM), D. Xu (NAOC), S. Bijavara Seshashayana (NOT and Malmo Univ.), report on behalf of a larger collaboration:
We observed the optical afterglow (Schneider et al., GCN 42535; Turpin et al., GCN 42538; Gritsevich et al., GCN 42539) of GRB 251103A (Hu et al., GCN 42534; Fermi GBM team, GCN 42536) with the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. A spectrum using grism #4 was secured starting on 2025 Nov 3.241 UT (61 min after the GRB), under good observing conditions. A total of 4 spectra of 600 s each were obtained, covering the wavelength range 3500-9600 AA.
In a preliminary reduction of the first spectrum, we detect a bright trace over the whole observed wavelength range. From the detection of multiple absorption features, including Fe II, Mg II, Mg I, and Ca II, we infer a redshift of z = 0.76.
GCN Circular 42539
Subject
GRB 251103A: BOOTES-2/TELMA optical afterglow
Date
2025-11-03T06:11:34Z (2 days ago)
From
Alberto Castro-Tirado at Inst.de Astro. de Andalucia <ajct@iaa.es>
Via
email
M. Gritsevich (Univ. if Helsinki), E. Fernandez-Garcia, A. J. Castro-Tirado, M. D. Caballero-Garcia, R. Sanchez-Ramirez, I. Perez-Garcia, S.-Y. Wu, S. Guziy (IAA-CSIC), C. Perez del Pulgar, A. Castellon, (Univ. de Malaga), Y.-D. Hu (GXU), M. Jelinek (ASU-CAS, Czech Rep.) and R. Fernandez-Munoz (IHSM/UMA-CSIC), on behalf of a larger collaboration, report:
Following the detection of GRB 2451103A by SVOM (Hu et al. GCNC 42534), the 0.6m BOOTES-2/TELMA robotic telescope at IHSM La Mayora (UMA-CSIC) in Algarrobo Costa (Malaga, Spain) pointed to the burst position on Nov 3 at 04:49:21 UT (i.e. 180s after trigger). In the first 60s image we clearly detected a new bright optical source, at coordinates (J2000) = 09:47:21.40 + 16:07:21.7 (+/- 0.5”), which we propose to be the optical afterglow to GRB 251103A, consistent with the source reported by the NOT (Shneider et al. GCNC 42537). Preliminary magnitude is 15.
GCN Circular 42538
Subject
GRB 251103A: LCO optical afterglow detection
Date
2025-11-03T06:09:45Z (2 days ago)
Edited On
2025-11-03T15:52:24Z (a day ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Edited By
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
D. Turpin (CEA/Irfu), D. B. Malesani (DAWN/NBI and Radboud), A. Saccardi (CEA/Irfu), C. Wu (NAOC), J. T. Palmerio (CEA/Irfu), L. P. Xin (NAOC), B. Cordier (CEA/Irfu), Y.-D. Hu, X. Tian (GXU), report on behalf of the SVOM mission team:
We observed the field of GRB 251103A (Hu et al., GCN 42534) with the LCO 1m telescope at Teide Observatory equipped with the Sinistro instrument.
Our observation started at 2025-11-03T05:23:30.775 about 37 min after the SVOM/ECLAIRs trigger time. We obtained 3x200 s exposures in the SDSS r filter. An uncatalogued bright optical candidate is well detected in our single images at RA, dec (J2000) = 146.83925 16.12272. This position is consistent with the optical counterpart reported by the NOT (Schneider et al. GCN 42535, GCN 42537).
We measure the following magnitude calibrated against the PanSTARRS DR1 catalog, and not corrected for Galactic extinction:
r = 16.91 +/- 0.01 (AB) at Tmid - T0 = 38.7 min
This project is funded by the SVOM collaboration.
GCN Circular 42537
Subject
GRB 251103A: NOT optical afterglow candidate (duplicate submission)
Date
2025-11-03T05:58:20Z (2 days ago)
Edited On
2025-11-03T17:25:17Z (a day ago)
From
Benjamin Schneider at MIT <bschn@mit.edu>
Edited By
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov>
Via
Web form
This is a duplicate of Circular 42535.
GCN Circular 42536
Subject
GRB 251103A: Fermi GBM Final Localization
Date
2025-11-03T05:57:12Z (2 days ago)
From
Matt Godwin <msg0028@uah.edu>
Via
Web form
The Fermi GBM team reports the detection of a likely LONG GRB
"At 04:46:28.11 UT on 03 November 2025, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 251103A (trigger 783837993/251103199).
The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 148.67, Dec = 15.71 (J2000 degrees, equivalent to J2000 9h 54m, +15d 42'),
with a statistical uncertainty of 2.03 degrees.
The angle from the Fermi LAT boresight is 112 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251103199/quicklook/glg_skymap_all_bn251103199.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251103199/quicklook/glg_healpix_all_bn251103199.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251103199/quicklook/glg_lc_medres34_bn251103199.gif"
GCN Circular 42535
Subject
GRB 251103A: NOT optical afterglow candidate
Date
2025-11-03T05:57:12Z (2 days ago)
Edited On
2025-11-03T16:23:43Z (a day ago)
From
Benjamin Schneider at MIT <bschn@mit.edu>
Edited By
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of Benjamin Schneider at MIT <bschn@mit.edu>
Via
Web form
B. Schneider (LAM), D. B. Malesani (DAWN/NBI and Radboud), D. Xu (NAOC), S. Bijavara Seshashayana (NOT and Malmo Univ.) report on behalf of a larger collaboration:
We observed the field of GRB 251103A (Hu et al., GCN 42534) using the Nordic Optical Telescope (NOT) equipped with the ALFOSC imager. Observations started on 2025-11-03 at 05:25:50 UT (39.5 min after trigger) and consisted of 2x300 s in the SDSS r band.
Within the ECLAIRs error circle, we detect a new source which is not seen in Pan-STARRS archival imaging of this field. Its coordinates are:
RA(J2000) = 09:47:21.41
Dec(J2000) = +16:07:21.8
with an estimated error of 0.3". Calibrated against nearby objects from Pan-STARRS, we measure AB magnitudes (not corrected for Galactic extinction):
r = 17.07 +/- 0.03
Further observations are ongoing.
GCN Circular 42534
Subject
GRB 251103A: SVOM detection of a bright burst
Date
2025-11-03T05:34:05Z (2 days ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
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Y.-D. Hu, X. Tian (GXU), W.-J. Xie, D.-H. Zhao (NAOC), P. Maggi (ObAS) report on behalf of the SVOM mission team:
At 2025-11-03T04:46:21 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 251103A (SVOM burst-id sb25110301).
The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network.
The burst was detected both by the Count-Rate Trigger (CRT) and the Image Trigger (IMT), which produced a sequence of 24 alerts. CRT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 103.94 in the [8-120] keV energy band over a time window of 10.20 seconds starting at 2025-11-03T04:46:26.
The localization of the best alert is R.A., Dec. 146.8375, 16.1296 degrees:
R.A. (J2000) = 9h47m21.00s
Dec. (J2000) = 16d07m46.66s
with a 90% confidence level (C.L.) radius of 2.13 arcmin (including systematic error of 2 arcmin added in quadrature).
Due to the angle constraints of sun, no immediate slew was performed on this burst.
No X-ray observation could be performed by SVOM/MXT for the time being. No optical observation could be performed by SVOM/VT for the time being.
The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. SVOM/ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. SVOM/GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. SVOM/MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE.
The Burst Advocate (BA) on shift for this alert is Youdong Hu: hyd@gxu.edu.cn .
Please contact the BA by email if you require additional information.