GCN Circular 44269

SVOM/GRM team: Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: Tais Maiolino (LUPM)
Report on behalf of the SVOM team:

SVOM/GRM was triggered in-flight by a bright short burst GRB 260407B (SVOM trigger reference: sb26040702) at 2026-04-07T10:58:55.900 UTC (T0). ECLAIRs was not collecting data at the time of this burst.

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 with a T90 of 0.11 +0.06/-0.03 s in the 15-5000 keV band. All the signal is detected lower than 100 keV.

The SVOM/GRM light curve can be found here:
https://www.bursthub.cn//admin/static/svgrb260407B.png

We note that both the soft spectrum and the short duration suggest a magnetar X-ray burst.

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)