TITLE: GCN CIRCULAR NUMBER: 13065 SUBJECT: GRB 120312A: CrAO optical upper limit DATE: 12/03/14 21:35:32 GMT FROM: Alexei Pozanenko at IKI, Moscow V. Rumyantsev, N. Pit' (CrAO), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of GRB 120312A (Stamatikos et al., GCN 13049) with AZT-11 telescope of CrAO observatory starting on March 12 (UT) 23:21:13 under moderate weather conditions and seeing of about 2.4 arsces. Within enhanced Swift-XRT position (Mangano et al., GCN 13053) we do not detected any optical source, in particular afterglow candidate (Tanvir et al., GCN 13055). A photometry is based on the USNO-B1.0 star 1138-0244157 (16:47:09.53 +23:51:17.4) assuming R=17.3: T_start UT T0+ Filter, Exposure, OT, uplim (3 sigma) (mid, d) (s) 23:21:13 0.3291 R 26x180 n/d 20.75