GCN Circular 42534

Y.-D. Hu, X. Tian (GXU), W.-J. Xie, D.-H. Zhao (NAOC), P. Maggi (ObAS) report on behalf of the SVOM mission team:

At 2025-11-03T04:46:21 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 251103A (SVOM burst-id sb25110301).

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 24 alerts. CRT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 103.94 in the [8-120] keV energy band over a time window of 10.20 seconds starting at 2025-11-03T04:46:26.

The localization of the best alert is R.A., Dec. 146.8375, 16.1296 degrees:
R.A. (J2000) = 9h47m21.00s
Dec. (J2000) = 16d07m46.66s
 with a 90% confidence level (C.L.) radius of 2.13 arcmin (including systematic error of 2 arcmin added in quadrature).

Due to the angle constraints of sun, 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 Youdong Hu: hyd@gxu.edu.cn .
Please contact the BA by email if you require additional information.