GCN Circular 43032

Z.-Y. Lin, F. Cangemi (APC), D. Turpin, S. Schanne (CEA/Irfu), F. Daigne (IAP)

At 2025-12-08T16:51:43 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 251208D (SVOM burst-id sb25120806).

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 1 alert. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 6.64 in the [8-120] keV energy band over a time window of 81.92 seconds starting at 2025-12-08T16:50:21.

The localization of the best alert is R.A., Dec. 337.5347, -0.3918 degrees:
R.A. (J2000) = 22h30m08.33s
Dec. (J2000) = -0d23m30.32s
 with a 90% confidence level (C.L.) radius of 11.77 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.

A SVOM ToO has been requested. MXT and VT ToO observation results will be reported in dedicated GCN Circulars.

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 Zhe-Yu Lin: zheyu.lin@apc.in2p3.fr.
Please contact the BA by email if you require additional information.