GRB 251025C
GCN Circular 42524
Subject
GRB 251025C: SVOM/GRM observation
Date
2025-10-30T17:03:31Z (3 days ago)
From
tanwj@ihep.ac.cn
Via
Web form
SVOM/GRM team: Wen-Jun Tan, Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: Sebastien Guillot (IRAP)
Report on behalf of the SVOM team:
SVOM/GRM was triggered in-flight by GRB 251025C (SVOM burst-id sb25102505) at 2025-10-25T23:08:41.000 (T0), which is also detected by Fermi/GBM (Fermi/GBM team, GCN # 42449), CALET (S. Torii, et al. GCN # 42467), AstroSat CZTI (A. Arya, et al. GCN # 42469) and Glowbug (R. Woolf, et al. GCN # 42490).
With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a significant peak followed by weak emission with a T90 of 30.4 +13.2/-12.6 s in the 15-5000 keV band.
The SVOM/GRM light curve can be found here:
https://www.bursthub.cn//admin/static/svgrb251025C.png
In addition, the position of this burst, as determined by Fermi/GBM (RA = 170.7, Dec = 54.9
, GCN #42449), is located at about 89 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view.
With this localization given by Fermi/GBM, the time-averaged spectrum from T0-2 to T0+30 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -0.97 +0.16/-0.14 and the cutoff energy, parameterized as Epeak, is 1450 +680/-440 keV. The event fluence (10-1000 keV) in this time interval is (1.06 +0.09/-0.27)E-05 erg/cm^2.
The localization of GRB 251025C in the 'Amati' relation diagram is shown at:
https://www.bursthub.cn//admin/static/svgrb251025C_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: Wen-Jun Tan (IHEP)(tanwj@ihep.ac.cn)
GCN Circular 42490
Subject
GRB 251025C: Glowbug gamma-ray detection
Date
2025-10-27T19:37:00Z (6 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 251025C, which was also detected by Fermi GBM (GCN 42449), CALET (GCN 42467), and AstroSat CZTI (GCN 42469).
Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2025-10-25 23:08:38.104 with a duration of 22.5 s and a total significance of about 46.8 sigma. The light curve comprises an initial fast rise/decay component in the T0 to T0+5s window, followed by secondary emission with slow exponential decay extending to T0+22.5s. Note that data from ~T0 to T0+1.5s and ~T0+3s to T0+5.5s 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 42469
Subject
GRB 251025C: AstroSat CZTI detection
Date
2025-10-27T09:48:20Z (6 days ago)
From
Anuraag Arya at IIT Bombay <aryaanuraag910@gmail.com>
Via
Web form
A. Arya (IITB), A. Goyal (IITB), S. Salunke (IUCAA), M. Tembhurnikar (IUCAA), Harsha K. H. (IUCAA), G. Waratkar (Caltech/IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long, bright GRB 251025C which was also detected by SWIFT BAT (DeLaunay et. al., GCN Circ. 42412), and CALET (Asaoka et. al., GCN Circ. 42414).
The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2025-10-25 23:08:37.50 UTC. The measured peak count rate associated with the burst is 201 (+35, -35) counts/s above the background in the combined data of three quadrants (out of four), with a total of 1467 (+193, -175) counts. The local mean background count rate was 216 (+2, -4) counts/s. Using cumulative rates, we measure a T90 of 18.4 (+1.3, -2.4) s.
The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2025-10-25 23:08:37.55 UTC. The measured peak count rate associated with the burst is 475 (+68, -78) counts/s above the background in the combined data of all quadrants, with a total of 3334 (+360, -502) counts. The local mean background count rate was 1311 (+8, -6) counts/s. We measure a T90 of 17.3 (+1.7, -2.0) s from the cumulative Veto light curve.
CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.
CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb
GCN Circular 42467
Subject
GRB 251025C: CALET Gamma-Ray Burst Monitor detection
Date
2025-10-27T05:49:55Z (6 days ago)
From
Yuta Kawakubo at Aoyama Gakuin University <kawakubo@phys.aoyama.ac.jp>
Via
Web form
S. Torii (Waseda U), A. Yoshida, T. Sakamoto, S. Sugita, Y. Kawakubo (AGU),
K. Yamaoka (Nagoya U), S. Nakahira (JAXA), Y. Asaoka (ICRR),
Y. Akaike, K. Kobayashi (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U),
N. Cannady (GSFC/UMBC), M. L. Cherry (LSU), S. Ricciarini (U of Florence),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:
The long GRB 251025C (Fermi GBM Final Real-time Localization: Fermi GBM team,
GCN Circ. 42449) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 23:08:37.27
UTC on 25 October 2025
(https://cgbm.calet.jp/cgbm_trigger/flight/1445468431/index.html).
The burst signal was seen by all CGBM detectors.
The burst light curve shows a multi-peaked structure that starts
at T+2.9 sec, peaks at T+3.5 sec, and ends at T+46.7 sec.
The T90 and T50 durations measured by the SGM data are 38.6 +/- 2.6 sec
and 15.1 +/- 1.4 sec (40-1000 keV), respectively.
The ground-processed light curve is available at
https://cgbm.calet.jp/cgbm_trigger/ground/1445468431/
The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.
GCN Circular 42463
Subject
Fermi GRB 251025C: Global MASTER-Net observations report
Date
2025-10-27T01:31:01Z (7 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-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 251025C ( Fermi GBM team, GCN 42449) errorbox 1 days 5134 sec after notice time and 1 days 5165 sec after trigger time at 2025-10-27 00:34:45 UT, with upper limit up to 18.6 mag. The observations began at zenith distance = 53 deg. The sun altitude is -33.9 deg.
The galactic latitude b = 58 deg., longitude l = 147 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=3023716
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
91596 | 2025-10-27 00:34:45 | MASTER-Kislovodsk | (11h 18m 11.77s , +54d 29m 42.9s) | C | 60 | 18.3 |
91596 | 2025-10-27 00:34:45 | MASTER-Kislovodsk | (11h 25m 08.42s , +54d 06m 43.1s) | C | 60 | 18.5 |
91675 | 2025-10-27 00:36:05 | MASTER-Kislovodsk | (11h 31m 25.80s , +55d 59m 16.1s) | C | 60 | 18.3 |
91675 | 2025-10-27 00:36:05 | MASTER-Kislovodsk | (11h 24m 10.23s , +56d 22m 21.0s) | C | 60 | 18.1 |
91755 | 2025-10-27 00:37:25 | MASTER-Kislovodsk | (11h 20m 02.72s , +52d 12m 24.9s) | C | 60 | 18.6 |
91755 | 2025-10-27 00:37:25 | MASTER-Kislovodsk | (11h 13m 24.71s , +52d 35m 17.4s) | C | 60 | 18.6 |
91835 | 2025-10-27 00:38:45 | MASTER-Kislovodsk | (11h 44m 17.61s , +54d 29m 12.9s) | C | 60 | 18.1 |
91835 | 2025-10-27 00:38:45 | MASTER-Kislovodsk | (11h 51m 11.39s , +54d 06m 05.0s) | C | 60 | 18.3 |
91916 | 2025-10-27 00:40:05 | MASTER-Kislovodsk | (11h 38m 20.05s , +52d 33m 52.5s) | C | 60 | 18.1 |
91996 | 2025-10-27 00:41:25 | MASTER-Kislovodsk | (11h 31m 44.37s , +58d 17m 35.7s) | C | 60 | 18.1 |
91996 | 2025-10-27 00:41:25 | MASTER-Kislovodsk | (11h 39m 22.93s , +57d 54m 25.4s) | C | 60 | 18.3 |
92236 | 2025-10-27 00:45:26 | MASTER-Kislovodsk | (11h 18m 07.62s , +54d 29m 57.0s) | C | 60 | 18.3 |
92236 | 2025-10-27 00:45:26 | MASTER-Kislovodsk | (11h 25m 08.02s , +54d 06m 32.4s) | C | 60 | 18.3 |
92316 | 2025-10-27 00:46:46 | MASTER-Kislovodsk | (11h 24m 08.47s , +56d 22m 38.2s) | C | 60 | 18.1 |
92316 | 2025-10-27 00:46:46 | MASTER-Kislovodsk | (11h 31m 24.36s , +55d 59m 08.8s) | C | 60 | 18.3 |
92396 | 2025-10-27 00:48:06 | MASTER-Kislovodsk | (11h 13m 23.20s , +52d 35m 54.1s) | C | 60 | 18.6 |
92396 | 2025-10-27 00:48:06 | MASTER-Kislovodsk | (11h 20m 01.70s , +52d 12m 36.7s) | C | 60 | 18.6 |
92476 | 2025-10-27 00:49:26 | MASTER-Kislovodsk | (11h 44m 17.35s , +54d 29m 36.7s) | C | 60 | 18.0 |
92476 | 2025-10-27 00:49:26 | MASTER-Kislovodsk | (11h 51m 11.53s , +54d 06m 03.7s) | C | 60 | 18.2 |
92556 | 2025-10-27 00:50:46 | MASTER-Kislovodsk | (11h 38m 19.67s , +52d 34m 11.0s) | C | 60 | 18.2 |
92644 | 2025-10-27 00:52:13 | MASTER-Kislovodsk | (11h 31m 43.71s , +58d 18m 05.9s) | C | 60 | 18.1 |
92644 | 2025-10-27 00:52:13 | MASTER-Kislovodsk | (11h 39m 22.66s , +57d 54m 30.1s) | C | 60 | 18.3 |
92890 | 2025-10-27 00:56:20 | MASTER-Kislovodsk | (11h 18m 04.46s , +54d 30m 35.0s) | C | 60 | 18.3 |
92890 | 2025-10-27 00:56:20 | MASTER-Kislovodsk | (11h 25m 08.64s , +54d 07m 10.4s) | C | 60 | 18.3 |
92970 | 2025-10-27 00:57:40 | MASTER-Kislovodsk | (11h 24m 09.70s , +56d 23m 16.5s) | C | 60 | 18.1 |
92970 | 2025-10-27 00:57:40 | MASTER-Kislovodsk | (11h 31m 27.23s , +55d 59m 48.2s) | C | 60 | 18.1 |
93050 | 2025-10-27 00:58:59 | MASTER-Kislovodsk | (11h 13m 21.24s , +52d 36m 14.7s) | C | 60 | 18.5 |
93050 | 2025-10-27 00:58:59 | MASTER-Kislovodsk | (11h 20m 01.17s , +52d 12m 57.7s) | C | 60 | 18.4 |
93129 | 2025-10-27 01:00:19 | MASTER-Kislovodsk | (11h 44m 15.91s , +54d 29m 56.6s) | C | 60 | 18.1 |
93129 | 2025-10-27 01:00:19 | MASTER-Kislovodsk | (11h 51m 11.44s , +54d 06m 23.7s) | C | 60 | 18.2 |
93210 | 2025-10-27 01:01:40 | MASTER-Kislovodsk | (11h 38m 18.17s , +52d 35m 14.3s) | C | 60 | 18.1 |
93290 | 2025-10-27 01:02:59 | MASTER-Kislovodsk | (11h 31m 44.06s , +58d 18m 37.3s) | C | 60 | 18.2 |
93290 | 2025-10-27 01:02:59 | MASTER-Kislovodsk | (11h 39m 24.39s , +57d 55m 02.7s) | C | 60 | 18.3 |
93533 | 2025-10-27 01:07:03 | MASTER-Kislovodsk | (11h 18m 02.58s , +54d 31m 12.2s) | C | 60 | 18.2 |
93533 | 2025-10-27 01:07:03 | MASTER-Kislovodsk | (11h 25m 08.82s , +54d 07m 52.0s) | C | 60 | 18.3 |
93613 | 2025-10-27 01:08:23 | MASTER-Kislovodsk | (11h 24m 07.26s , +56d 23m 53.1s) | C | 60 | 18.1 |
93613 | 2025-10-27 01:08:23 | MASTER-Kislovodsk | (11h 31m 26.30s , +56d 00m 29.1s) | C | 60 | 18.3 |
93693 | 2025-10-27 01:09:43 | MASTER-Kislovodsk | (11h 13m 21.14s , +52d 37m 05.7s) | C | 60 | 18.6 |
93693 | 2025-10-27 01:09:43 | MASTER-Kislovodsk | (11h 20m 02.47s , +52d 13m 53.0s) | C | 60 | 18.6 |
93793 | 2025-10-27 01:11:23 | MASTER-Kislovodsk | (11h 44m 13.86s , +54d 30m 52.5s) | C | 60 | 18.1 |
93793 | 2025-10-27 01:11:23 | MASTER-Kislovodsk | (11h 51m 10.90s , +54d 07m 24.6s) | C | 60 | 18.1 |
93879 | 2025-10-27 01:12:49 | MASTER-Kislovodsk | (11h 38m 18.19s , +52d 35m 51.5s) | C | 60 | 18.1 |
93959 | 2025-10-27 01:14:09 | MASTER-Kislovodsk | (11h 31m 42.25s , +58d 19m 32.6s) | C | 60 | 18.1 |
93959 | 2025-10-27 01:14:09 | MASTER-Kislovodsk | (11h 39m 23.62s , +57d 56m 04.3s) | C | 60 | 18.4 |
94399 | 2025-10-27 01:21:29 | MASTER-Kislovodsk | (11h 17m 59.49s , +54d 30m 58.7s) | C | 60 | 18.4 |
94399 | 2025-10-27 01:21:29 | MASTER-Kislovodsk | (11h 25m 03.05s , +54d 07m 53.1s) | C | 60 | 18.3 |
94478 | 2025-10-27 01:22:48 | MASTER-Kislovodsk | (11h 24m 10.99s , +56d 25m 08.0s) | C | 60 | 18.2 |
94478 | 2025-10-27 01:22:48 | MASTER-Kislovodsk | (11h 31m 32.09s , +56d 01m 57.7s) | C | 60 | 18.3 |
94558 | 2025-10-27 01:24:08 | MASTER-Kislovodsk | (11h 13m 15.55s , +52d 39m 26.4s) | C | 60 | 18.6 |
94558 | 2025-10-27 01:24:08 | MASTER-Kislovodsk | (11h 19m 58.90s , +52d 16m 26.6s) | C | 60 | 18.5 |
94640 | 2025-10-27 01:25:30 | MASTER-Kislovodsk | (11h 44m 14.15s , +54d 30m 13.3s) | C | 60 | 18.1 |
94640 | 2025-10-27 01:25:30 | MASTER-Kislovodsk | (11h 51m 12.53s , +54d 06m 56.7s) | C | 60 | 18.4 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 42449
Subject
GRB 251025C: Fermi GBM Final Real-time Localization
Date
2025-10-25T23:19:13Z (8 days ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
Via
email
The Fermi GBM team reports the detection of a likely LONG GRB
At 23:08:40 UT on 25 Oct 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251025C (trigger 783126525.293544 / 251025964).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 170.7, Dec = 54.9 (J2000 degrees, equivalent to J2000 11h 22m, 54d 53'), with a statistical uncertainty of 2.2 degrees.
The angle from the Fermi LAT boresight is 103.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251025964/quicklook/glg_skymap_all_bn251025964.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/bn251025964/quicklook/glg_healpix_all_bn251025964.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251025964/quicklook/glg_lc_medres34_bn251025964.gif