GCN Circular 40947
Subject
EP250704a / GRB 250704B - REM observations
Event
Date
2025-07-04T13:08:04Z (a day ago)
From
Matteo Ferro at INAF-OAB <matteo.ferro@inaf.it>
Via
Web form
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 EP250704a (Li et al., GCN 40941) / GRB 250704B (Wang et al., GCN 40940) 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 July 04 at 08:28:07 UT (i.e. 11.3 min after the burst), and lasted for about 2 hours.
From preliminary inspection, we do not detect any counterpart at the position of the optical afterglow candidate (Schneider et al., GCN 40942, Malesani et al., GCN 40945) down to the following 3sigma limits:
r > 18.7 (AB; calibrated against the Pan-STARRS catalogue),
at a mid-time of 11.4 min after the trigger;
H > 14.8 (Vega; calibrated against the 2MASS catalogue),
at a mid-time of 11.3 min after the trigger.