GCN Circular 41078

P. Maggi (ObAS), M. Brunet, L.Bouchet (IRAP), D. Gotz (CEA) report on behalf of the SVOM mission team:

At 2025-07-13T17:06:26 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 250713A (SVOM burst-id sb25071320).

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 7 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 14.04 in the [8-120] keV energy band over a time window of 40.96 seconds starting at 2025-07-13T17:06:02.

The localization of the best alert is R.A., Dec. 336.9666, 38.7686 degrees (J2000) with a 90% confidence level (C.L.) radius of 5.84 arcmin (including systematic error of 2 arcmin added in quadrature).

The lightcurve shows a short spike which could be followed by an extended emission.

SVOM slewed to the burst.

SVOM/MXT began observing the field at 2025-07-13T17:08:48 UTC, 142 seconds after T0. Using onboard processed data we found an uncatalogued X-ray source located at R.A., Dec. 336.9045, 38.7670 degrees:
R.A. (J2000) = 22h27m37.09s
Dec. (J2000) = 38d46m01.31s
with a 90% C.L. radius of 55 arcseconds (including systematic error of 25 arcsec added in quadrature).

This location is 2.90 arcminutes from the ECLAIRs onboard position. This position may be improved as more data is received.

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 Pierre Maggi: pierre.maggi@astro.unistra.fr.
Please contact the BA by email if you require additional information.