TITLE:   GCN CIRCULAR
NUMBER:  42185
SUBJECT: GRB 251009A: SVOM/GRM observation of short GRB with possible tail emission
DATE:    25/10/10 13:32:03 GMT
FROM:    Chenwei Wang at IHEP <cwwang@ihep.ac.cn>


SVOM/GRM team: Chen-Wei Wang, Shu-Xu Yi, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)

SVOM/ECLAIRs team: Frédéric Piron (LUPM)

Report on behalf of the SVOM team:

SVOM/GRM was triggered in-flight by a short burst GRB 251009A (SVOM trigger reference: sb25100902) at 2025-10-09T15:58:56.500 UTC (T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN#42179).

With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a narrow spike followed by a weak tail emission with a T90 of 0.32 +0.05/-0.11 s in the 15-5000 keV band, which is somewhat similar to extragalactic magnetar giant flare.

The SVOM/GRM light curve can be found here:
https://www.bursthub.cn//admin/static/svgrb251009A.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)