TITLE: GCN CIRCULAR NUMBER: 42759 SUBJECT: GRB 251116D: SVOM/GRM observation of a long GRB DATE: 25/11/19 11:43:21 GMT FROM: Xinghao Luo at SVOM/GRN <2952704891@qq.com> GRB 251116D: SVOM/GRM observation of a long GRB SVOM/GRM team: Xing-Hao Luo, Chen-Wei Wang, Zheng-Hang Yu, Yue Huang, Shi-Jie Zheng, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Marius Brunet (IRAP) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by GRB 251116D(SVOM trigger reference: sb25111606) at 2025-11-16T19:22:37.000 UTC(T0), which is also detected by AstroSat/CZTI (Harsha K. H. et.al., GCN #42715) , Konus-Wind and Glowbug (C.C. Cheung et.al., GCN #42718). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of multi-pulses and a possible bump with a T90 of 45 +3/-21 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb251116D.png In addition, the position of this burst, as determined by Glowbug (RA=148.0 , DEC=-37.6, with a raidus of 3.7 der (95% confidence), C.C. Cheung et.al., GCN #42718), is located at about 131 degrees form the SVOM optical axis, which is outside the ECLAIRs field of view. However this burst is seen by ECLAIRs by reflection on the atmosphere. With this localization, the time-averaged spectrum from T0-2 to T0+20 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.52 +0.21/-0.17 and the cutoff energy, parameterized as Epeak, is 498 +294/-139 keV. The event fluence (10-1000keV) in this time interval is (3.31 +0.18/-0.21)E-05 erg/cm^2. The localization of GRB 251116D in the 'Amati' relation diagram is shown at: https://www.bursthub.cn//admin/static/svgrb251116D_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 point of contact for this burst is: Xing-Hao Luo (2952704891@qq.com) View this GCN Circular online at https://gcn.nasa.gov/circulars/42759. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...