GCN Circular 37574
Subject
GRB 240919A / EP240919a: SVOM/GRM observation
Date
2024-09-20T13:43:44Z (6 months ago)
From
Chenwei Wang at IHEP <cwwang@ihep.ac.cn>
Via
Web form
SVOM/GRM team: Chen-Wei Wang, Yong-Wei Dong, Jiang-Tao Liu, Shi-Jie Zheng, Jian-Chao Sun, Wen-Jun Tan, Jiang He, Min Gao, Hao-Xuan Guo, Yue Huang, Lu Li, Yong-Ye Li, Hong-Wei Liu, Xin Liu, Hao-Li Shi, Li-Ming Song, You-Li Tuo, Hao-Xi Wang, Jin Wang, Jin-Zhou Wang, Ping Wang, Rui-Jie Wang, Yu-Xi Wang, Bo-Bing Wu, Shao-Lin Xiong, Jian-Ying Ye, Yi-Tao Yin, Wen-Hui Yu, Fan Zhang, Li Zhang, Peng Zhang, Shuang-Nan Zhang, Wen-Long Zhang, Yan-Ting Zhang, Shu-Min Zhao, Xiao-Yun Zhao, Chao Zheng (IHEP), Maria-Grazia Bernardini (LUPM/INAF-OAB), Laurent Bouchet (IRAP), David Corre (CEA), Tais Maiolino (LUPM), Frédéric Piron (LUPM), Stéphane Schanne (CEA), Jingwei Wang (IAP)
SVOM JSWG: Jian-Yan Wei (NAOC), Bertrand Cordier (CEA), Shuang-Nan Zhang (IHEP), Stéphane Basa (LAM), JeanLuc Attéia (IRAP), Arnaud Claret (CEA), Zi-Gao Dai (USTC), Frédéric Daigne (IAP), Jin-Song Deng (NAOC), Andrea Goldwurm (APC), Diego Götz (CEA), Xu-Hui Han (NAOC), Cyril Lachaud (APC), En-Wei Liang (GXU), Yu-Lei Qiu (NAOC), Susanna Vergani (Obs.Paris), Jing Wang (NAOC), Chao Wu (NAOC), Li-Ping Xin (NAOC), Bing Zhang (UNLV)
report on behalf of the SVOM team:
During the commissioning phase, the SVOM/GRM detected a weak long burst, GRB 240919A, at about 80 s after the trigger time (2024-09-19T14:47:40 UT, T0) of EP240919a (Liang et al., GCN 37561).
With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a single pulse with a duration of about 20 s (i.e. T0+82 s to T0+102 s) in the energy range of 30-300 keV.
The GRM light curve can be found here:
https://www.bursthub.cn/admin/static/svgrb240919A.png
Although this burst is quite weak in GRM, it was also detected by Fermi/GBM (Liang et al., GCN 37563) and INTEGRAL/SPI-ACS (James Rodi et al., GCN 37573), supporting that it is of astrophysical origin.
Due to the weakness of GRB 240919A, GRM is unable to localize it reliably on its own. However, using the EP240919a localization of R.A. = 334.2797, DEC = -9.7362 (J2000) from EP (Liang et al., GCN 37561), the incident angles of the three GRDs of GRM are about 96, 69 and 46 degrees respectively. The facts that the smallest-angle detector (i.e. GRD03) has the highest signal of this burst and that there is a time coincidence between GRB 240919A and EP240919a support that GRB 240919A is very likely associated with EP240919a (also by Liang et al., GCN 37563).
At the time of this burst ECLAIRs was not in operational mode.
Further follow-up observations are encouraged.
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)