TITLE: GCN CIRCULAR NUMBER: 40110 SUBJECT: GRB 250407A: SRG/ART-XC afterglow detection DATE: 25/04/07 19:48:18 GMT FROM: Sergey Molkov serge.molkov@gmail.com
S. Molkov, A. Tkachenko, I. Mereminskiy, A. Semena, A. Lutovinov, I. Lapshov, V. Arefiev, A. Shtykovskiy and D. Karasev on behalf of the ART-XC team (IKI Moscow) report:
During the ongoing all sky survey the Mikhail Pavlinsky ART-XC telescope passed through the localization area of GRB250407A (GCN 40104, GCN 40105) and detected a new X-ray source with coordinates: (RA,Dec)=(110.7564,36.7979) J2000; the 1 sigma statistical error radius is 20 arcsec. The source was in the FoV of the ART-XC telescope during ~20 seconds with a central time of 2025-04-07T17:08:20 UTC (on-board time), approximately 90 minutes after the burst had been detected by GBM (GCN 40104).
The mean flux during the transition was about 1.4e-10 ergs/s/cm2 in the 4-12 keV energy band. We expect that it's an afterglow detection of GRB 250407A.
Urgent Swift/XRT follow-up observation was requested to obtain precise localization.
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