TITLE: GCN CIRCULAR NUMBER: 20181 SUBJECT: GRB161117A: REM optical and NIR afterglow detection DATE: 16/11/17 08:52:18 GMT FROM: Paolo D'Avanzo at INAF-OAB P. D'Avanzo, D. Fugazza, S. Covino, A. Melandri (INAF/OAB) report on behalf of the REM team: We observed the field of GRB 161117A (Cummings et al., GCN 20179) with the 60-cm robotic telescope REM located at the La Silla Observatory (Chile). The observations started at 01:37:05 UT, 89 seconds after the burst, and were carried out simultaneously in the g, r, i, z and H bands. A preliminary photometry indicates that the optical and NIR afterglow (Cummings et al., GCN 20179; Malesani et al. GCN 20180) is detected with a magnitude H = 16.4 +/- 0.3 at t-t0 = 233 s, and r = 18.3 +/- 0.3 at t-t0 = 808 s. Magnitudes are in the AB system and have been calibrated with respect to the 2MASS (H-band) and APASS (r-band) catalogues.