TITLE: GCN CIRCULAR NUMBER: 38832 SUBJECT: GRB 250103B: REM optical/NIR upper limits DATE: 25/01/06 15:59:56 GMT FROM: Matteo Ferro at INAF-OAB matteo.ferro@inaf.it
M. Ferro, R. Brivio, P. D’Avanzo, S. Covino, D. Fugazza (INAF-OAB) report on behalf of the REM team:
We observed the field of GRB 250103B detected by Swift (Eyles-Ferris et al., GCN 38796), also detected by SVOM (Bouchet et al., GCN 38797) with the REM 60cm robotic telescope located at the ESO observatory of La Silla (Chile). The observations were carried in the g, r, i, z, J, H, K bands, starting on 2025 January 04 at 00:47:49 UT (i.e. 9.1 hours after the Swift trigger), and lasting for about 1 hour. From preliminary photometry we do not detect any optical or NIR counterpart at the optical afterglow position (Qiu et al., GCN 38813; Habeeb et al., GCN 38820; Turpin et al., GCN 38822) down to the following 3sigma magnitude upper limits:
r > 20.4 (AB; calibrated against the SkyMapper catalogue) at a mid-time of t - t0 = 9.5 hr after the trigger,
H > 17.3 (Vega; calibrated against the 2MASS catalogue) at a mid-time of t - t0 = 9.4 hr after the trigger.
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