GCN Circular 40923
Subject
GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
Event
Date
2025-07-03T16:44:09Z (a day 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: Alexis Coleiro (APC)
Report on behalf of the SVOM team:
On July 2, 2025, SVOM/GRM detected a hard X-ray activity using event-by-event data downloaded via the X-band ground station. This activity is consistent with detections reported by Fermi/GBM (Fermi GBM Team, GCN #40883, #40885, #40886, #40890, #40891), Swift/BAT (James DeLaunay et al., GCN #40903), and Konus-Wind (D. Frederiks et al., GCN #40914). These transient events may be associated with the soft X-ray transient EP250702a (GCN #40906), also detected by MAXI/GSC (GCN #40910).
At the time of the hard X-ray triggers, the refined position reported by EP/WXT (R.A. = 284.6911 deg, DEC = -7.8715 deg J2000, GCN#40906) was approximately 48 degrees from the SVOM optical axis, which is just outside the ECLAIRs field of view. GRD 02 and GRD 03 provided continuous coverage of this transient activity (with incident angle of 30 and 48 degrees, respectively) from the very beginning to about 2025-07-02T15:20:00, except passing the SAA and Earth’s shadow.
The SVOM/GRM light curve of GRB 250702D can be found here:
https://www.bursthub.cn//admin/static/svgrb250702D.png
We note that the report here is very preliminary, refined analysis is still ongoing.
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)