GRB 251009B
GCN Circular 42198
Subject
GRB 251009B: SVOM/GRM observation of short GRB
Date
2025-10-11T08:12:07Z (2 days ago)
From
Chenwei Wang at IHEP <cwwang@ihep.ac.cn>
Via
Web form
SVOM/GRM team: Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: Stéphane Schanne (CEA), Jean-Luc Atteia (IRAP)
Report on behalf of the SVOM team:
SVOM/GRM was triggered on-ground by a short burst GRB 251009B at 2025-10-09T01:51:15.350 UTC (T0), which is also detected by Insight-HXMT (Wang et al., GCN#42187), Glowbug (C.C. Cheung et al., GCN#42188).
With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a double spikes with a T90 of 1.2 +0.75/-0.45 s in the 15-5000 keV band, the signal mainly appears above 100 keV. No significant signal is detected by ECLAIRs, suggesting the burst is outside the ECLAIRs FoV.
The SVOM/GRM light curve can be found here:
https://www.bursthub.cn//admin/static/svgrb251009B.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 42188
Subject
GRB 251009B (short): Glowbug gamma-ray detection
Date
2025-10-10T16:14:04Z (3 days ago)
Edited On
2025-10-10T20:28:47Z (3 days ago)
From
C.C. Cheung at Naval Research Lab <Teddy.Cheung@nrl.navy.mil>
Edited By
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of C.C. Cheung at Naval Research Lab <Teddy.Cheung@nrl.navy.mil>
Via
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C.C. Cheung, R. Woolf, 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 251009B, which was also detected by Insight-HXMT (GCN 42187).
Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2025-10-09 01:51:14.176 with a duration of 1.0 s and a total significance of about 13.1 sigma. The light curve comprises two peaks at ~T0+0.2s and ~T0+0.9s.
The best-fit localization is RA, Decl. (J2000, deg) = 155.1, 24.1 with a radius of 25.3 deg (95% confidence), with a highly uncertain systematic uncertainty.
The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.
Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test 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 42187
Subject
GRB 251009B: Insight-HXMT detection of a short burst
Date
2025-10-10T15:50:38Z (3 days ago)
From
Chenwei Wang at IHEP <cwwang@ihep.ac.cn>
Via
Web form
Chen-Wei Wang, Cheng-Kui Li, Shao-Lin Xiong, and Chao Zheng report on behalf of the Insight-HXMT team:
At 2025-10-09T01:51:15.250 (T0), Insight-HXMT/HE detected the burst GRB 251009B, which is also detected by SVOM/GRM.
The Insight-HXMT/HE light curve mainly consists of double pulses with a T90 of 1.00 +0.15/-0.05 s. The total counts from this burst is 2442 counts.
The HXMT/HE light curve can be found here:
https://www.bursthub.cn//admin/static/hxmtgrb251009B.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.