TITLE: GCN CIRCULAR NUMBER: 43909 SUBJECT: GRB 260225A: SVOM/ECLAIRs refined analysis DATE: 26/03/03 14:56:16 GMT FROM: SVOM_group <svomgroup@bao.ac.cn> M. Brunet, O. Godet (IRAP), W.J. Xie (NAOC), F. Daigne (IAP),Yinuo Ma (NAOC), Li Zhang (IHEP) 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 260225A (SVOM burst-id sb26022501 – GCN 43829, trigger time T0 = 2026-02-25T08:51:15 UTC). The burst that triggered ECLAIRs shows a single peak lightcurve. The burst duration before the satellite slew is estimated through imaging to be around 59 s (from T0-21 s up to T0+209 s) in the 4-120 keV energy band. Some emission below 20 keV is still seen after the slew up to T0+209 s. The time-averaged spectrum before the satellite slew, i.e. from T0-21 s to T0+38 s in the 5-120 keV energy band is best fitted by a broken power-law model with a first photon index of -1.00 +0.20/-0.16, a break energy of 21.7 +4.4/-3.9 keV and a second photon index of -2.06 +0.22/-0.28. With this model, the 4-120 keV fluence is (1.00 +0.04/-0.26)e-6 erg/cm^2. The spectral parameters indicate that this burst is likely to be an X-ray flash. 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/43909. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...