TITLE: GCN CIRCULAR NUMBER: 40363 SUBJECT: GRB 250506A: REM optical/NIR upper limits DATE: 25/05/06 14:25:25 GMT FROM: Matteo Ferro at INAF-OAB matteo.ferro@inaf.it
M. Ferro, R. Brivio, P. D'Avanzo, M. G. Bernardini, S. Covino, D. Fugazza (INAF-OAB) report on behalf of the REM team:
We observed the field of GRB 250506A detected by SVOM/ECLAIRs (Wang et al., GCN 40358) and Fermi GBM (Fermi GBM team, GCN 40355; Sonawane et al., GCN 40362) 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 06 at 02:43:22 UT (i.e. 20 minutes after the burst), and lasted for about 3 hours.
From preliminary inspection, we do not detect any possible counterpart inside the SVOM error circle, in agreement with other follow-up observations (de Ugarte Postigo et al., GCN 40359; Liu et al., GCN 40360; Beardmore et al., GCN 40361), down to the following 3sigma limits:
r > 19.8 (AB; calibrated against the Pan-STARRS catalogue), at a mid-time of 54 minutes after the trigger;
H > 16.4 (Vega; calibrated against the 2MASS catalogue), at a mid-time of 31 minutes after the trigger.
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