GCN Circular 43723
Subject
GRB 260204A: SVOM/ECLAIRs refined analysis
Event
Date
2026-02-13T14:24:15Z (12 hours ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
M. Brunet, O. Godet (IRAP), M. Pillas, M. Dennefeld (IAP) on behalf of the ECLAIRs team.
Using the event-by-event data downloaded through the X-band ground station, we report further analysis of ECLAIRs observations of GRB 260204A (SVOM burst-id sb26020403, GCN 43613), which was also detected by Fermi/GBM as a sub-threshold event (GCN 43618).
ECLAIRs started collecting data at T0-8.91 s (T0 = 2026-02-04T14:48:49 UT), the Fermi sub-threshold detection starting at T0-47 s shows that part of the burst emission has been missed by ECLAIRs.
The burst as seen by ECLAIRs is featureless in the 4-120 keV lightcurve. The burst emission is detected up to T0+220 s.
The time-averaged spectrum before the slew from T0-8.91 s to T0+36.03 s in the 4-120 keV energy range is best fitted by a power-law model with a photon index of 1.76 +0.12/-0.11. With this model, the fluence in the 4-120 keV energy band is (7.55 +0.55/-1.02)e-7 erg/cm².
After the slew, the GRB emission is still detectable below 10 keV for around 80 s, but it is rather faint. So, it is not possible to derive meaningful spectral information.
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 irap.omp.eu)