GRB 241029A : Detection and localization of a bright long GRB by SVOM/ECLAIRs

During the commissioning phase, the SVOM/ECLAIRs telescope detected and localized a bright long duration GRB 241029A at 2024-10-29T02:19:53 UTC (Tb), previously detected by Fermi (Fermi GBM team, GCN circular 37932), and by SVOM/GRM (SVOM reference: sb241002901). The onboard trigger was not in operations, the following information was obtained by reprocessing on ground the data in the flight trigger algorithms. The burst was detected by the Count-Rate Trigger (CRT) and Image Trigger (IMT) which produced 22 Alert messages. The best Alert was obtained by CRT in the 8-120 keV energy band with a signal-to-noise ratio of 67.1 in a time window of 20.48 s starting at Tb. The event location is RA, Dec = 325.327, Dec: 5.086 (J2000). The statistical uncertainty on this position is 1.5 arcminutes to which we recommend adding 2 arcminutes of systematic uncertainty in quadrature. SVOM did not slew to the burst since automated slewing was not enabled. The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), 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: b.cordier AT cea.fr.