GCN Circular 42581

M.G. Bernardini (INAF-OAB, LUPM), M. Pillas (IAP), N. Dagoneau (CEA), F. Lacreu (IAP)

At 2025-11-04T17:30:58 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 251104A (SVOM burst-id sb25110404).

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

The burst was only detected by the Image Trigger (IMT), which produced a sequence of 6 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 10.82 in the [5-8] keV energy band over a time window of 655.36 seconds starting at 2025-11-04T17:28:14.

The localization of the best alert is R.A., Dec. 26.5099, 15.5077 degrees:
R.A. (J2000) = 1h46m02.39s
Dec. (J2000) = 15d30m27.56s
 with a 90% confidence level (C.L.) radius of 7.39 arcmin (including systematic error of 2 arcmin added in quadrature).

No immediate slew was performed on this burst.
No X-ray observation could be performed by SVOM/MXT for the time being.
No optical observation could be performed by SVOM/VT for the time being.

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 Maria Grazia Bernardini: maria.bernardini@inaf.it.
Please contact the BA by email if you require additional information.