TITLE: GCN CIRCULAR NUMBER: 19920 SUBJECT: GRB 160912A: Mondy optical observations DATE: 16/09/13 13:19:46 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Volnova (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), E. Mazaeva (IKI), I. Korobtsev (ISTP) report on behalf of larger GRB follow-up collaboration: We observed the field of the GRB 160912A (Cannizzo et al. GCN 19912) with AZT-33IK telescope of Sayan observatory (Mondy) starting on Sep., 12 (UT) 18:14:25. We obtained several images in R-filter. We clearly detected optical afterglow (Tanvir et al., GCN 1991). Coordinates of the afterglow are (J2000) 20 05 59.64 +57 33 55.2 with uncertainty of 0.4 arcsec in both coordinates. The afterglow is 5 arcsec from nearby star (USNO-B1.0 1475-0371357 (J2000) RA = 20:06:00.32 Dec = +57:33:57.0 R2 = 18.21) and within enhanced XRT position (Beardmore et al. GCN 19915). Preliminary photometry of the afterglow is following Date UT start t-T0 Filter Exp. OT UL (3 sigma) (mid, days) (s) 2016-09-12 18:14:25 0.10883 R 30*120 22.57 +/-0.08 23.5 Photometry is based on nearby USNO-B1.0 stars ID RA Dec R2 2 1475-0371275 20:05:49.83 +57:33:12.9 17.09 3 1475-0371352 20:05:59.47 +57:32:43.8 17.46 4 1475-0371174 20:05:41.08 +57:33:00.0 17.43 5 1475-0371504 20:06:16.57 +57:32:46.8 17.62 The finding chart can be found at http://grb.rssi.ru/GRB160912A/GRB160912A_160912_AZT33IK_fc.png