TITLE: GCN CIRCULAR NUMBER: 39775 SUBJECT: GRB 250317C: SVOM/GRM observation of a long burst DATE: 25/03/19 02:11:00 GMT FROM: Yue Wang m18509381757@163.com
SVOM/GRM team: Yue Wang, Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: Tais Maiolino, Frédéric Piron (LUPM), Stéphane Schanne (CEA), Jean-Luc Atteia (IRAP)
Report on behalf of the SVOM team:
SVOM/GRM was triggered in-flight by GRB 250317C (SVOM trigger reference: sb25031702) at 2025-03-17T17:31:28.000 (T0). This burst was also detected by GECAM-B and AstroSat CZTI (Wang et al., GCN 39768; S. Salunke et al., GCN 39771).
With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of single main pulse with a T90 of 23.4 +3.7/-2.0 s in the 15-5000 keV band.
In addition, ECLAlRs was taking data and did not trigger, since the position of this burst, as determined by GECAM-B (GCN 39768, RA: 320.42 deg, DEC: -16.07 deg, Error: 8.59 deg), is located at about 108.3 degrees from the SVOM optical axis, and outside the ECLAIRs field of view.
The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250317C.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/GRM point of contact for this burst is: Yue Wang (IHEP) (yuewang@ihep.ac.cn)
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