GCN Circular 46150

M. G. Bernardini (INAF/LUPM), M. Gnaoui (IAP), and R. Hamburg (USRA) report on behalf of the SVOM/ECLAIRs team

At 2026-11-04T20:36:44 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 261104A (SVOM burst-id sb26110402).

The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network.

The burst was detected both by the Count-Rate Trigger (CRT) and the Image Trigger (IMT), which produced a sequence of 5 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 8.02 in the [5-20] keV energy band over a time window of 20.48 seconds starting at 2026-11-04T20:36:31.

The localization of the best alert is R.A., Dec. 6.2999, -54.4612 degrees:
R.A. (J2000) = 0h25m11.98s
Dec. (J2000) = -54d27m40.50s
 with a 90% confidence level (C.L.) radius of 9.81 arcmin (including systematic error of 2 arcmin added in quadrature).

The SVOM/ECLAIRs light curve showed a single broad peak structure with a T90 duration of about 40 s.

SVOM slewed to the burst.

MXT and VT began observing the field after the slew. The analysis of the data will be published in a future circular.

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. SVOM/ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. SVOM/GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. SVOM/MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE.

The Burst Advocate (BA) on shift for this alert is Mouad GNAOUI: mouad.gnaoui@iap.fr.
Please contact the BA by email if you require additional information.