TITLE: GCN CIRCULAR NUMBER: 40545 SUBJECT: GRB 250520A: 10 GHz VLA Afterglow Confirmation DATE: 25/05/24 00:21:19 GMT FROM: Genevieve Schroeder at Cornell University genevieveschroeder@u.northwestern.edu
G. Schroeder (Cornell), W. Fong (Northwestern), T. Laskar (Utah) report:
We re-observed the location of the short-duration GRB 250520A (Eyles-Ferris et al., GCN 40491; SVOM/GRM Team, GCN 40495; Tembhurnikar et al., GCN 40497; Frederiks et al., GCN 40512; Asaoka et al., GCN 40519; Dafcikova et al., GCN 40540) with the Karl G. Jansky Very Large Array (VLA) in C configuration under program 25A-063 (PI Schroeder) at a mid time of 2025 May 21 at 11:24 UT (3.36 days post-burst) for a total of 2.25 hours at a mean frequencies of 6 and 10 GHz.
The radio source detected in the previous 10 GHz VLA observation at 1.28 days (Schroeder et al., GCN 40518) is no longer detected at 3.36 days, to a 3 sigma limit of 10 microJy. Given the fading of this source, and its positional coincidence with the XRT afterglow (Goad et al., GCN 40494), we consider it to be the radio afterglow of GRB 250520A.
We thank the VLA staff for quickly approving and executing these observations.
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