TITLE: GCN CIRCULAR NUMBER: 39535 SUBJECT: GRB 250225B: VLT/HAWKI near-infrared observations DATE: 25/02/28 17:08:01 GMT FROM: Nusrin Habeeb at University of Leicester <nh312@leicester.ac.uk> B.C. Rayson (U. Leicester), N. Habeeb (U. Leicester), N. R. Tanvir (U. Leicester), R. A. J. Eyles-Ferris (U. Leicester), R. Brivio (INAF-OAB), M. Ferro (INAF-OAB), A J. Levan (Radboud and Warwick), D. B. Malesani (DAWN/NBI and Radboud) report on behalf of the Stargate collaboration: We observed the field of the GRB 250225B (Williams et al., GCN 39473) with the ESO Very Large Telescope UT4, equipped with the HAWK-I near-infrared camera. We obtained a 20 min exposure Ks band, starting at 09:12:18.45 UT on 2025-02-27, i.e. 1.56 days after the Swift trigger. The observations were obtained under good seeing conditions, with a measured seeing of 0.96″ in the Ks band. We detect the optical afterglow candidate reported by Schneider et al. (GCN 39494) and Yang et al. (GCN 39495) at coordinates: RA(J2000) = 20:24:33.81 DEC(J2000) = -41:28:25.4 Its Vega magnitude is Ks = 19.382 +- 0.057, calibrated using nearby stars in the 2MASS catalogue. From VISTA survey images, we measured a 2-sigma upper limit to be Ks(Vega) > 19.56. No other obviously variable sources are seen, to the depth of the VISTA comparison images. We thank the staff at the VLT, for the rapid execution of these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/39535. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...