TITLE: GCN CIRCULAR NUMBER: 40168 SUBJECT: GRB 250419A: SVOM detection of a soft burst DATE: 25/04/19 03:22:36 GMT FROM: SVOM_group svomgroup@bao.ac.cn

B.-T. Wang (YNAO, CAS), Y.H. Cheng (SWIFAR,YNU), W. J. Xie, D. H. ZHAO (NAO, CAS), C. W. WANG (IHEP) on behalf of the SVOM mission team.

At 2025-04-19T02:29:32 UTC (Tb) SVOM/ECLAIRs triggered on the gamma-ray burst GRB 250419A (SVOM burst-id sb25041901).

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 5 alerts. CRT provided the alert with the best signal-to-noise-ratio (SNR) of 8.62 in the [5-8] keV energy band over a time window of 20.40 seconds starting at Tb.

The localization of the best alert is R.A., Dec 202.387, 7.086 degrees: RA (J2000) = 13h29m32.97s Dec (J2000) = 7d05m09.92s with a 90% C.L. radius of 9.15 arcmin (including systematic error of 2 arcmin added in quadrature).

SVOM slewed to the burst.

No prompt X-ray observation could be performed by MXT.

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 Boting Wang: wangbaiting@ynao.ac.cn. Please contact the BA by email if you require additional information regarding the SVOM follow-up of this burst.

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