TITLE: GCN CIRCULAR NUMBER: 44666 SUBJECT: GRB 260515A: SVOM/ECLAIRs refined analysis DATE: 26/05/19 14:14:04 GMT FROM: SVOM_group <svomgroup@bao.ac.cn> M. Brunet, L. Bouchet (IRAP), A. Saccardi (CEA/ Irfu), report on behalf of the SVOM/ECLAIRs team Using the event-by-event data downloaded through the X-band ground station, we report further analysis of SVOM/ECLAIRs observations of GRB 260515A (SVOM burst-id sb26051504 – GCN 44622, trigger time T0 = 2026-05-15T19:08:19 UTC), which was also detected by Konus-Wind (GCN 44647). The burst that triggered ECLAIRs shows a FRED like shape light curve preceded by a faint hard precursor at T0-4.2s. The burst duration is T90 = 16.33 +0.54/-0.35 s in the 4-120 keV energy band. The time-averaged spectrum from T0-0.31 s to T0+16.0 s in the energy range 5-120 keV is best fitted by a powerlaw model with alpha = -1.69 +/-0.04. With this model, the 4-120 keV fluence is (1.09 -0.07/+0.04)e-6 erg/cm² and the 4-120 keV photon flux is 2.26 -0.06/+0.04 ph/cm²/s. All the quoted errors are at the 68% confidence level. The Space-based multi-band astronomical 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 CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. The SVOM/ECLAIRs point of contact for this burst is: Marius Brunet (IRAP) (marius.brunet at utoulouse.fr) View this GCN Circular online at https://gcn.nasa.gov/circulars/44666. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...