GCN Circular 40313

Y. Wang (PMO, CAS), J.X Cao (GXU), L. Bouchet, M. Brunet (IRAP), C. Plasse (CEA)
on behalf of the SVOM mission team.

SVOM/ECLAIRs triggered on the gamma-ray burst GRB 250502A (SVOM burst-id sb25050205) starting at 2025-05-02T08:46:27 UTC (Tb)

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

The burst was detected by the Image Trigger (IMT). A sequence of 3 alerts was produced. IMT provided the alert with the best signal-to-noise-ratio (SNR) of 8.94 in the 8-50 keV energy band over a time window of 40.96 seconds starting at Tb.

The localization of the best alert is R.A., Dec. 206.479, -10.643 degrees:
R.A. (J2000) = 13h45m54.84s
Dec. (J2000) = -10h38m34.49a
with a 90% confidence level (C.L.) radius of 8.84 arcmin (including systematic error of 2 arcmin added in quadrature).

SVOM slewed to the burst.

MXT began observing the field after the slew. The analysis of MXT data will be published in a future circular.

VT began observing the field after the slew. The analysis of the recorded images will be published in a future circular gathering information on the follow-up of the SVOM optical instruments.

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.

The Burst Advocate (BA) on shift for this burst is Y. Wang: wangyun@pmo.ac.cn.
Please contact the BA by email if you require additional information regarding the SVOM follow-up of this burst.