TITLE: GCN CIRCULAR NUMBER: 39103 SUBJECT: GRB 250128B: VLA possible radio detection DATE: 25/01/31 01:38:41 GMT FROM: Genevieve Schroeder at Cornell University genevieveschroeder@u.northwestern.edu
G. Schroeder (Cornell), T. Laskar (Utah), W. Fong, J. Rastinejad (Northwestern) report:
We observed the position of the short GRB 250128B (Evans et al., GCN 39058; Fermi GBM team, GCN 39057) with the Karl G. Jansky Very Large Array (VLA) under program 25A-063 (PI: Schroeder) beginning on 2025 Jan 29 at 10:05 UT (0.74 days post-burst) for 0.75 hours at a mean frequency of 6 GHz.
Based on preliminary analysis, within the enhanced XRT position (Evans et al., GCN 39069) we find a possible source with a peak flux density of ~20 uJy at the position:
RA(J2000): 15:25:42.032 Dec(J2000): -00:32:22.72
with an uncertainty of 0.1 arcsec in each coordinate. This position is ~2 arcsec offset from the optical/near IR sources reported in Yang et al. (GCN 39084) and Rastinejad et al. (GCN 39088). At present we cannot determine if this possible source is associated with the burst. We note that these observations were taken 2.7 hr prior to those reported in Ricci et al. (GCN 39093).
We thank the VLA staff for quickly approving and executing these observations. Further observations are planned to assess the temporal behavior of the possible source.
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