GRB 251023A
GCN Circular 42451
Subject
GRB 251023A: SVOM/GRM observation
Date
2025-10-26T03:54:05Z (18 hours ago)
From
Chenwei Wang at IHEP <cwwang@ihep.ac.cn>
Via
Web form
SVOM/GRM team: Chen-Wei Wang, Zheng-Hang Yu, Wen-Jun Tan, Yue Huang, Shi-Jie Zheng, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: Feliu Lacreu (IAP)
Report on behalf of the SVOM team:
SVOM/GRM was triggered in-flight by a burst GRB 251023A (SVOM trigger reference: sb25102301) at 2025-10-23T05:57:44.000 UTC (T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN#42385) and Glowbug (R. Woolf, GCN#42408).
With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of multiple peaks with a T90 of 63.5 +19.5/-5.5 s in the 15-5000 keV band.
The SVOM/GRM light curve can be found here:
https://www.bursthub.cn//admin/static/svgrb251023A.png
In addition, the position of this burst, as determined by Fermi/GBM (RA= 39.87, DEC= -6.53, GCN#42385), is located at about 51 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view.
With this localization, the time-averaged spectrum from T0-2 to T0+70 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -0.45 +0.25/-0.26 and the cutoff energy, parameterized as Epeak, is 143 +26/-19 keV. The event fluence (10-1000 keV) in this time interval is (5.47 +0.55/-0.56)E-6 erg/cm^2.
The localization of GRB 251023A in the 'Amati' relation diagram is shown at:
https://www.bursthub.cn//admin/static/svgrb251023A_amati.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 42408
Subject
GRB 251023A: Glowbug gamma-ray detection
Date
2025-10-23T20:15:38Z (3 days ago)
From
richard.s.woolf.civ@us.navy.mil
Via
Web form
R. Woolf, C.C. Cheung, M. Kerr, J.E. Grove (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge, D. Kocevski (MSFC), and M.S. Briggs (UAH) report:
The Glowbug gamma-ray telescope [1,2,3], operating on the International Space Station, reports the detection of GRB 251023A, which was also detected by Fermi/GBM (GCN 42385).
Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2025-10-23 05:57:43.480 with a duration of 4.1 s and a total significance of about 9.1 sigma. The light curve comprises a single peak. Note that data from ~T0-1s to T0+1s suffered from deadtime in various detectors.
The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.
Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS, and operated until 2024 April when it was put in safe storage on orbit. Glowbug was removed from storage and resumed operation on 2025 September 12.
[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959
[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O
[3] Woolf, R.S. et al. 2024, Proc. SPIE, 13151, id. 1315108
Distribution Statement A: Approved for public release. Distribution is unlimited.
GCN Circular 42390
Subject
Fermi GRB 251023A: Global MASTER-Net observations report
Date
2025-10-23T09:15:24Z (4 days 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-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 251023A ( Fermi GBM team, GCN 42385) errorbox 665 sec after notice time and 686 sec after trigger time at 2025-10-23 06:09:10 UT, with upper limit up to 20.7 mag. The observations began at zenith distance = 29 deg. The sun altitude is -40.0 deg.
The galactic latitude b = -56 deg., longitude l = 180 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=3021658
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
717 | 2025-10-23 06:09:10 | MASTER-OAFA | (02h 36m 41.44s , -06d 42m 24.3s) | C | 60 | 20.6 |
792 | 2025-10-23 06:10:25 | MASTER-OAFA | (02h 36m 48.65s , -06d 42m 09.1s) | C | 60 | 20.6 |
880 | 2025-10-23 06:11:53 | MASTER-OAFA | (02h 51m 27.06s , -04d 47m 02.9s) | C | 60 | 20.4 |
956 | 2025-10-23 06:13:09 | MASTER-OAFA | (02h 51m 25.90s , -04d 46m 08.3s) | C | 60 | 20.4 |
1045 | 2025-10-23 06:14:38 | MASTER-OAFA | (02h 29m 25.20s , -08d 34m 50.8s) | C | 60 | 20.3 |
1120 | 2025-10-23 06:15:53 | MASTER-OAFA | (02h 37m 24.96s , -08d 34m 57.2s) | C | 60 | 20.4 |
1197 | 2025-10-23 06:17:10 | MASTER-OAFA | (02h 29m 18.79s , -08d 34m 44.5s) | C | 60 | 20.3 |
1272 | 2025-10-23 06:18:25 | MASTER-OAFA | (02h 37m 30.89s , -08d 35m 06.2s) | C | 60 | 20.4 |
1353 | 2025-10-23 06:19:46 | MASTER-OAFA | (02h 44m 42.03s , -08d 34m 33.8s) | C | 60 | 20.6 |
1429 | 2025-10-23 06:21:02 | MASTER-OAFA | (02h 52m 48.50s , -08d 32m 57.2s) | C | 60 | 20.5 |
1503 | 2025-10-23 06:22:16 | MASTER-OAFA | (02h 44m 48.52s , -08d 34m 42.6s) | C | 60 | 20.7 |
1579 | 2025-10-23 06:23:32 | MASTER-OAFA | (02h 52m 49.17s , -08d 35m 05.7s) | C | 60 | 20.4 |
1654 | 2025-10-23 06:24:47 | MASTER-OAFA | (02h 44m 47.30s , -08d 35m 42.7s) | C | 60 | 20.6 |
1733 | 2025-10-23 06:26:07 | MASTER-OAFA | (02h 52m 04.95s , -06d 40m 17.4s) | C | 60 | 20.2 |
1895 | 2025-10-23 06:28:48 | MASTER-OAFA | (02h 51m 58.29s , -06d 40m 20.1s) | C | 60 | 20.2 |
1981 | 2025-10-23 06:30:14 | MASTER-OAFA | (02h 30m 14.33s , -10d 30m 32.8s) | C | 60 | 20.2 |
2057 | 2025-10-23 06:31:30 | MASTER-OAFA | (02h 38m 20.88s , -10d 28m 16.3s) | C | 60 | 20.5 |
2132 | 2025-10-23 06:32:45 | MASTER-OAFA | (02h 38m 22.92s , -10d 28m 22.0s) | C | 60 | 20.4 |
2215 | 2025-10-23 06:34:08 | MASTER-OAFA | (02h 59m 21.23s , -06d 41m 00.5s) | C | 60 | 20.0 |
2369 | 2025-10-23 06:36:42 | MASTER-OAFA | (02h 59m 20.42s , -06d 42m 09.2s) | C | 60 | 20.1 |
3339 | 2025-10-23 06:52:52 | MASTER-OAFA | (02h 39m 52.78s , -06d 23m 46.0s) | C | 60 | 19.5 |
3405 | 2025-10-23 06:53:58 | MASTER-OAFA | (02h 39m 52.75s , -06d 23m 44.1s) | C | 60 | 19.5 |
3470 | 2025-10-23 06:55:03 | MASTER-OAFA | (02h 39m 52.71s , -06d 23m 42.5s) | C | 60 | 19.6 |
3536 | 2025-10-23 06:56:09 | MASTER-OAFA | (02h 39m 52.68s , -06d 23m 41.2s) | C | 60 | 20.6 |
3601 | 2025-10-23 06:57:15 | MASTER-OAFA | (02h 39m 52.66s , -06d 23m 39.7s) | C | 60 | 20.6 |
3667 | 2025-10-23 06:58:20 | MASTER-OAFA | (02h 39m 52.65s , -06d 23m 38.5s) | C | 60 | 20.6 |
3734 | 2025-10-23 06:59:27 | MASTER-OAFA | (02h 39m 52.64s , -06d 23m 37.5s) | C | 60 | 20.6 |
3800 | 2025-10-23 07:00:33 | MASTER-OAFA | (02h 39m 52.62s , -06d 23m 36.4s) | C | 60 | 20.5 |
3865 | 2025-10-23 07:01:38 | MASTER-OAFA | (02h 39m 52.61s , -06d 23m 35.4s) | C | 60 | 20.5 |
3931 | 2025-10-23 07:02:44 | MASTER-OAFA | (02h 39m 52.60s , -06d 23m 34.4s) | C | 60 | 20.4 |
3997 | 2025-10-23 07:03:50 | MASTER-OAFA | (02h 39m 52.60s , -06d 23m 33.5s) | C | 60 | 20.5 |
4063 | 2025-10-23 07:04:56 | MASTER-OAFA | (02h 39m 52.59s , -06d 23m 32.6s) | C | 60 | 20.6 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 42385
Subject
GRB 251023A: Fermi GBM Final Localization Correction
Date
2025-10-23T07:33:17Z (4 days ago)
From
A. Holzmann Airasca at University of Trento and INFN Bari <a.holzmannairasca@unitn.it>
Via
Web form
The Fermi GBM team reports the detection of a likely LONG GRB
"At 05:57:43.66 UT on 23 October 2025, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 251023A (trigger 782891868/251023248).
This trigger was initially classified as distant particles by the flight software,
but is in fact a GRB.
The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 39.87, Dec = -6.53 (J2000 degrees, equivalent to J2000 02h 39m, -06d 31'),
with a statistical uncertainty of 3.12 degrees.
The angle from the Fermi LAT boresight is 89 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251023248/quicklook/glg_skymap_all_bn251023248.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/bn251023248/quicklook/glg_healpix_all_bn251023248.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251023248/quicklook/glg_lc_medres34_bn251023248.gif"