GCN Circular 39910

M. Brunet, J. Malzac, L. Bouchet, O. Godet (IRAP), C. Plasse (CEA), L.P. Xin (NAOC)
report on behalf of the SVOM mission team.

SVOM/ECLAIRs triggered on the gamma-ray burst GRB 250328A (SVOM burst-id sb25032803) starting at 2025-03-28T16:56:56.3 UTC (Tb). 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 (SNR) of 6.85 in the [8-120] keV energy band over a time window of 20.48 seconds starting at Tb.

The light curve showed a single peak with a duration of about 15s.

The localization of the best alert is R.A., Dec 215.9771, 25.8825 degrees:
RA (J2000) = 14h23m54.51s
Dec (J2000) = 25d52m56.83s
with a 90% C.L. radius of 11.42 arcmin (including systematic error of 2 arcmin added in quadrature).

No immediate slew was performed on this burst, because its significance was below the slew threshold. A SVOM ToO will be performed. 

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 Marius Brunet: marius.brunet@irap.omp.eu.
Please contact the BA by email if you require additional information regarding the SVOM follow-up of this burst.