GCN Circular 40518
Subject
GRB 250520A: 10 GHz VLA radio source
Date
2025-05-22T02:15:16Z (4 days ago)
From
Genevieve Schroeder at Cornell University <genevieveschroeder@u.northwestern.edu>
Via
Web form
G. Schroeder (Cornell), J. Rastinejad, W. Fong (Northwestern), T. Laskar (Utah) report:
We 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) with the Karl G. Jansky Very Large Array (VLA) in D->C configuration under program 25A-063 (PI Schroeder) at a mid time of 2025 May 21 at 09:22 UT (1.28 days post-burst) for 1.25 hours at a mean frequency of 10 GHz.
In preliminary analysis, we detect a 4-sigma radio source with a flux density of ~18 microJy at the position:
RA(J2000) = 18:49:08.57
Dec(J2000) = -11:52:07.7
with an uncertainty of ~0.8" in each coordinate. This position is consistent with the X-ray position (Goad et al., GCN 40494) but offset (~2") from the optical source reported by Xin et al. (GCN 40500), which has not yet shown any evidence for fading (Yang et al., GCN 40511). At the position of the radio source, we do not detect any optical emission in Gemini i-band imaging (Rastinejad et al., GCN 40504). Further observations are planned to assess the variability of the radio source and its connection, if any, to GRB 250520A.
We thank the VLA staff for quickly approving and executing these observations.