TITLE: GCN CIRCULAR NUMBER: 13679 SUBJECT: GRB 120811C: optical observations DATE: 12/08/18 22:18:42 GMT FROM: Alexei Pozanenko at IKI, Moscow L. Elenin (KIAM), A. Volnova (SAI MSU), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of GRB 120811C (Barlow et al., GCN 13622) with 0.45-m telescope of ISON-NM observatory starting on Aug. 12 (UT) 03:25:07. We took several unfiltered images of 30 s exposures. The optical afterglow (Denisenko et al., GCN 13623) is marginally detected in co-added frames at coordinates (J2000) 13:18:43.98 +62:18:03.4 with uncertainty of 0.5 arcsec in both coordinates. A preliminary photometry of co-added frames is based on the USNO-B1.0 (R2) nearby stars is following: T_start, T0+, Exposure, OT, UL (3 sigma) (UT) mid, d (s) 03:25:07 0.5095 1800 21.5 +/-0.5 21.2