TITLE:   GCN CIRCULAR
NUMBER:  40435
SUBJECT: EP250511a: REM optical/NIR observations
DATE:    25/05/12 09:02:36 GMT
FROM:    Riccardo Brivio at INAF-OAB <riccardo.brivio@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 EP250511a detected by EP/WXT (Lian et al., GCN 40429) 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, J, H, and K bands, started on 2025 May 11 at 22:53:26 UT (i.e. 14.9 hr after the burst), and lasted for about 1 hour.

From preliminary inspection, we do not detect any possible counterpart consistent with the candidate optical afterglow (Schneider et al., GCN 40431; Li et al., GCN 40433) down to the following 3sigma limits:

r > 19.4 (AB; calibrated against the Pan-STARRS catalogue),
at a mid-time of 15.3 hr after the trigger;

H > 16.2 (Vega; calibrated against the 2MASS catalogue),
at a mid-time of 15.0 hr after the trigger.