GCN Circular 37318

SVOM/ECLAIRs commissioning team: Hervé Le Provost, Stéphane Schanne, Frédéric Chateau, Nicolas Dagoneau (CEA), Olivier Godet, Laurent Bouchet, Sebastien Guillot, Juliette Alaux (IRAP), Frédéric Piron (LUPM), Karine Mercier, Marie-Claire Charmeau, Stefano Crepaldi (CNES), Alexis Coleiro (APC)

SVOM JSWG: Jian-Yan Wei (NAOC), Bertrand Cordier (CEA), Shuang-Nan Zhang (IHEP), Stéphane Basa (LAM), Jean-Luc Atteia (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/ECLAIRs telescope triggered and located a very soft and weak X-ray transient at 2024-08-28T13:12:43 UT (TtimeTb), called GRB 240828B. The burst was detected by the Image Trigger (IMT) with a signal to noise ratio of 7.1 in the 5-8 keV energy band on a single time window of 81.92 s starting at TimeTb. Even if the source is weak, the quality indicators of the reconstructed image are good.

The transient location is RA, Dec = 63.36, 16.71 (J2000). This is about 27 degrees from the ECLAIRs optical axis. The statistical uncertainty on this position is 12 arcminutes, to which we recommend to add 10 arcminutes of systematic uncertainty. The field of view was free of the Earth. 

SVOM did not slew to the burst since automated slewing is not yet enabled.

The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), French Space Agency (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. ECLAIRs was developed jointly by APC, CEA, CNES and IRAP.

The SVOM point of contact for this burst is: s.schanne AT cea.fr