GCN Circular 45247
Subject
GRB 260727A: SVOM/GRM observation
Event
Date
2026-07-29T01:59:56Z (2 months ago)
From
Yue Wang <m18509381757@163.com>
Via
Web form
SVOM/GRM team: Yue Wang, Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: Feliu Lacreu (IAP)
Report on behalf of the SVOM team:
SVOM/GRM was triggered in flight by GRB 260727A at 2026-07-27T00:22:01.000 UTC (T0), which is also detected by SVOM/ECLAIRs (Li et al., GCN #45220), AstroSat/CZTI (Harsha K. H. et al., GCN #45225), Glowbug (Cheung et al., GCN #45233) and Konus-Wind (Svinkin et al., GCN #45242).
With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of multiple broad peaks with a T90 of 53 +3/-2 s in the 15-5000 keV band.
The SVOM/GRM light curve can be found here:
https://www.bursthub.cn/gcn/2026/svgrb260727A.png
In addition, the position of this burst, as determined by EP/FXT (RA = 331.7702 deg, Dec = 74.5296 deg, Err = 10 arcsec; GCN #45236), is located at about 23.7 degrees from the SVOM optical axis.
With this localization, the time-averaged spectrum from T0-3 to T0+70 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -0.64 +0.09/-0.09 and the cutoff energy, parameterized as Epeak, is 81.7 +3.0/-2.7 keV. The event fluence (10-1000 keV) in this time interval is (1.352 +0.034/-0.032)E-05 erg/cm^2.
The localization of GRB 260727A in the 'Amati' relation diagram is shown at: https://www.bursthub.cn/gcn/2026/svgrb260727A_amati.png
The localization of GRB 260727A in the 'Yonetoku' relation diagram is shown at:
https://www.bursthub.cn/gcn/2026/svgrb260727A_yonetoku.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)