TITLE: GCN CIRCULAR NUMBER: 39500 SUBJECT: GRB 250225B: REM NIR upper limits DATE: 25/02/26 19:12:09 GMT FROM: Matteo Ferro at INAF-OAB matteo.ferro@inaf.it
M. Ferro, R. Brivio, P. D'Avanzo, S. Covino, D. Fugazza, S. Campana (INAF-OAB), and L. Izzo (INAF-OACn and DARK/NBI) report on behalf of the REM team:
We observed the field of Swift detected GRB250225B (Williams et al., GCN 39473), also seen by SVOM (Zhang et al., GCN 39493) with the REM 60 cm robotic telescope located at the ESO observatory of La Silla (Chile). The observations were carried in the J, H, and K bands, started on 2025 February 26 at 08:27:46 UT (i.e. 12.8 hr after the burst), and lasted for about 1 hour.
From preliminary inspection inside the BAT error circle, we do not find any counterpart at the position of the reported optical/NIR candidate counterpart (Schneider et al., GCN 39494, Yang et al., GCN 39495) down to the following 3sigma limit:
H > 17.5 (Vega; calibrated against the 2MASS catalogue),
at a mid-time of 13.2 hours after the trigger
J > 17.1 (Vega; calibrated against the 2MASS catalogue)
at a mid-time of 13.4 hours after the trigger.
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