GCN Circular 40913
Subject
GRB 250702F: REM optical afterglow detection
Event
Date
2025-07-03T12:13:57Z (a day ago)
From
Riccardo Brivio at INAF-OAB <riccardo.brivio@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 GRB 250702F detected by Swift/BAT (Klingler et al., GCN 40894) and Fermi/GBM (Fermi GBM Team, GCN 40892) 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 02 at 22:50:33 UT (i.e. 1.7 hr after the burst), and lasted for about 1 hour.
From preliminary inspection, we detect the counterpart in the optical images at the position of the optical afterglow (Klingler et al., GCN 40894; Jelinek et al., GCN 40895; Kumar et al., GCN 40896; Lipunov et al., GCN 40899; Martin-Carrillo et al., GCN 40900; de Ugarte Postigo et al., GCN 40901; Angulo et al., GCN 40907; Becerra et al., GCN 40911) with the following magnitude:
r = 18.3 +/- 0.2 (AB; calibrated against the Pan-STARRS catalogue),
at a mid-time of 1.7 hr after the trigger.
No NIR counterpart is detected down the following 3sigma upper limit:
H > 15.5 (Vega; calibrated against the 2MASS catalogue),
at a mid-time of 1.7 hr after the trigger.