GCN Circular 40513
Subject
GRB 250521B: SVOM detection of a burst through offline search
Date
2025-05-21T16:50:38Z (3 days ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
A. Foisseau, C. Lachaud (APC), M. Brunet (IRAP), N. Dagoneau (CEA)
report on behalf of the SVOM team:
The SVOM/ECLAIRs telescope detected a transient source, labelled GRB 250521B, starting at 2025-05-21T04:19:17.8 UTC (Tb), through an offline search with the event-by-event data downloaded through the X-band ground station.
The burst was detected within several energy ranges in a 5.12 seconds timescale. The best detection is obtained by the image trigger with a signal-to-noise ratio of 7.2 within 8-50 keV over a time window of 5.12 seconds starting at Tb.
The lightcurve consists of a single pulse lasting around 5s.
The localization of the source is RA, Dec = 200.822, 1.766 degrees:
RA (J2000) = 13h23m17.3s
Dec (J2000) = 01d45m57.6s
with a 90% C.L. radius of 12.2 arcmin (including systematic error of 6 arcmin added in quadrature).
We note that no bright X-ray sources are found in the error box.
The Space 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. ECLAIRs was developed jointly by APC, CEA, CNES, and IRAP.
The SVOM point of contact for this event is : A. Foisseau : foisseau@apc.in2p3.fr
Please contact him by email if you require additional information regarding the SVOM follow-up of this burst.