TITLE: GCN CIRCULAR NUMBER: 39154 SUBJECT: GRB 250205A: SVOM detection of a burst DATE: 25/02/05 22:18:47 GMT FROM: SVOM_group svomgroup@bao.ac.cn
A. Saccardi, T. Sadibekova, N. Dagoneau, H. Goto, S. Schanne (CEA), Ch. Van Hove (IJCLab) report on behalf of the SVOM mission team:
The SVOM/ECLAIRs telescope triggered and located the long duration GRB 250205A (sb25020504) starting at 2025-02-05T21:24:38 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 both the on-board Count-Rate Trigger (CRT) and Image Trigger (IMT) and 8 alerts were received. The best detection is obtained by IMT with a signal-to-noise ratio of 19.3 in the 8-120 keV energy band over a time window of 40.96 s starting at Tb.
The localization of the best Alert is RA, Dec = 113.459, 32.365 (J2000). The uncertainty on this position is 4.5 arcminutes at 90% C.L. which includes 2 arcminutes of systematic uncertainty in quadrature.
SVOM performed an automatic slew on this burst.
MXT began observing the field at 2025-02-05T21:34:32, 593 seconds after the SVOM trigger.
Using onboard processed data we found an uncatalogued X-ray source located in J2000 at RA, Dec 113.534, 32.370 degrees
RA (J2000) = 7h34m08s Dec (J2000) = 32d22m14s
with an uncertainty radius at 90% C.L. of 80 arcseconds. This location is 3.8 arcminutes from the ECLAIRs onboard position. This position may be improved as more data is received.
VT began observing the field at 2025-02-05T21:41:52, 1033 seconds after the SVOM trigger. 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 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 Advocates (BAs) on shift for this burst are Andrea Saccardi, Tatyana Sadibekova (andrea.saccardi@cea.fr). Please contact the BA by email if you require additional information regarding the SVOM follow-up of this burst.
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