GCN Circular 45719
Subject
GRB 260920A: SVOM/GRM observation
Event
Date
2026-09-24T08:35:39Z (a day ago)
From
Xinghao Luo at IHEP <2952704891@qq.com>
Via
Web form
SVOM/GRM team: Xing-Hao Luo, Yue Wang, Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: O. Godet (IRAP)
Report on behalf of the SVOM team:
SVOM/GRM was triggered in-flight by GRB 260920A (SVOM trigger reference: sb26092001) at 2026-09-20T10:32:35.000 (T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #45658) and AstroSat CZTI (A. Arya et.al., GCN#45672).
With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of muplti-pulses with a T90 of 23.5 +/-5 s in the 15-5000 keV band.
The SVOM/GRM light curve can be found here:
https://www.bursthub.cn/gcn/2026/svgrb260920A.png
In addition, the position of this burst, as determined by Fermi/GBM (RA = 293.0, Dec = -31.8, with a statistical uncertainty of 1.1 degrees, GCN #45658), is located at about 99 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view and nothing significant seen above 50 keV in the ECL light curve.
With this localization, the time-averaged spectrum from T0-11.5 to T0+22.0 s is best fitted by a power law function with an exponential high energy cutoff. The power law index is -1.05 +0.22/-0.19 and the cutoff energy, parameterized as Epeak, is 397 +150/-87 keV. The event fluence (10-1000 keV) in this time interval is (2.20 +0.19/−0.20)E-05 erg/cm^2.
The localization of GRB 260920A in the ‘Amati’ relation diagram is shown at:
https://www.bursthub.cn/gcn/2026/svgrb260920A_amati.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: Xing-Hao Luo (IHEP) (luoxh@ihep.ac.cn)