TITLE: GCN CIRCULAR NUMBER: 30772 SUBJECT: GRB 210905A: REM NIR afterglow detection DATE: 21/09/05 07:42:23 GMT FROM: Paolo D'Avanzo at INAF-OAB <pda.davanzo@gmail.com> P. D'Avanzo, A. Melandri, S. Covino, D. Fugazza (INAF-OAB), on behalf of the REM team, report: We observed the field of GRB 210905A (Sonbas, et al., GCN 30765) with the REM 60cm robotic telescope located at the ESO premise of La Silla (Chile). The observations were carried in the g, r, i, z, J, H and K bands, starting on 2021 September 05 at 00:19:49 UT (i.e. 428 seconds after the burst) and lasting for about three hours. At the position of the optical afterglow (Strausbaugh & Cucchiara, GCN Circ. 30769) we detected an uncatalogued source in all NIR bands. From preliminary photometry we derive the following magnitude: H = 14.82 +/- 0.15 (Vega; calibrated against the 2MASS catalogue) at a mid time of t-t0 = 469 seconds.