TITLE: GCN CIRCULAR NUMBER: 43963 SUBJECT: GRB 260131A/B: radio detection with the VLA DATE: 26/03/11 16:32:24 GMT FROM: Stefano Giarratana at INAF-OAB <s.giarratana@ira.inaf.it> S. Giarratana (INAF-OAB), M. Giroletti (INAF-IRA), G. Ghirlanda (INAF-OAB), N. Di Lalla (Stanford Univ.), N. Omodei (Stanford Univ.), O. S. Salafia (INAF-OAB), L. Nava (INAF-OAB) At 00:39:44 UT on 2026 February 5 (T_mid = 4.78 days post-burst) the Karl G. Jansky VLA observed the field of GRB 260131A/B (Fermi GBM team, GCN 43579, 43585; Sugai et al., GCN 43580; Konus-Wind team, GCN 43590; Insight-HXMT team, GCN 43591; GRID Collaboration, GCN 43605) in three bands, with central frequencies of 6, 10 and 15 GHz. The standard 3C48 was used as bandpass, flux density and phase calibrator. From a preliminary analysis, an unresolved radio source is detected at a position (J2000): RA: 01:38:51.308 +- 0.001 Dec: +34:19:40.84 +- 0.01 consistent with the X-ray (Sugai et al., GCN 43580; Jiang et al., GCN 43600;), optical (GOTO collaboration, GCN 43586; Lee et al., GCN 43587; García García, GCN 43599; Jayaraman et al., GCN 43606; Zhu et al., GCN 43607; KAIT GRB team, GCN 43609; MISTRAL GRB collaboration, GCN 43610; Volnova et al., GCN 43632, 43670; Gupta et al., GCN 43708) and infrared (Shi et al., GCN 43601) position of the transient. The preliminary analysis yields the following results: ================================================================ T_mid Freq Peak r.m.s. Beam PA [days] [GHz] [uJy/b] [uJy/b] [arcsec^2] [deg] ================================================================ 4.78 6 669 6 0.94x0.34 74 4.78 10 1018 6 0.60x0.21 70 4.78 15 1671 9 0.49x0.15 68 ================================================================ No source is detected with a >3sigma confidence level at the aforementioned position in the VLASS. We would like to thank the staff of the VLA for approving, executing, and processing the observations. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. These observations were carried out as part of project SF181027, approved in the framework of the Fermi - NRAO joint program agreement. View this GCN Circular online at https://gcn.nasa.gov/circulars/43963. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...