TITLE: GCN CIRCULAR NUMBER: 40865 SUBJECT: GRB 250628A: REM optical/NIR upper limits DATE: 25/06/28 20:02:00 GMT FROM: Matteo Ferro at INAF-OAB matteo.ferro@inaf.it
R. Brivio, M. Ferro, P. D'Avanzo, S. Covino, D. Fugazza (INAF-OAB) report on behalf of the REM team:
We observed the field of GRB 250628A detected by Swift/BAT (Ferro et al., GCN 40853) with the REM 60 cm robotic telescope located at the ESO observatory of La Silla (Chile). The observations were carried in the g, r, i, z, and H bands, started on 2025 June 28 at 06:17:20 UT (i.e. 5.4 hr after the burst), and lasted for about 1 hour. From preliminary inspection, we do not detect any possible counterpart within the Swift/XRT error region (Evans et al., GCN 40854) down to the following 3sigma limits:
r > 20.1 (AB; calibrated against the SkyMapper catalogue), at a mid-time of 5.9 hr after the trigger;
H > 14.8 (Vega; calibrated against the 2MASS catalogue), at a mid-time of 5.4 hr after the trigger.
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