GCN Circular 42702

M. Pillas (IAP), M.G. Bernardini (INAF-OAB, LUPM), M. Brunet (IRAP), report on behalf of the SVOM mission team:

At 2025-11-16T15:32:36 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 251116B (SVOM burst-id sb25111604).

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 Count-Rate Trigger (CRT), which produced a sequence of 1 alert. CRT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 6.67 in the [8-120] keV energy band over a time window of 10.20 seconds starting at 2025-11-16T15:32:26.

The localization of the best alert is R.A., Dec. 18.8320, -41.0854 degrees:
R.A. (J2000) = 1h15m19.68s
Dec. (J2000) = -41d05m07.42s
 with a 90% confidence level (C.L.) radius of 11.72 arcmin (including systematic error of 2 arcmin added in quadrature).

Due to the detection significance being below the slew threshold, no immediate slew was performed on this burst.
Further observations by SVOM/VT are currently scheduled.

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 Marion Pillas: marion.pillas@iap.fr.
Please contact the BA by email if you require additional information.