TITLE: GCN CIRCULAR NUMBER: 11192 SUBJECT: GRB 100902A: optical observation at Mt.Terskol DATE: 10/09/03 11:20:36 GMT FROM: Alexei Pozanenko at IKI, Moscow M. Andreev, A. Sergeev (Terskol Branch of Institute of Astronomy) and A.Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: We observed the field of the Swift GRB 100902A (Sakamoto et al, GCN 11181) with the Z-600 telescope of Mt.Terskol observatory in R-filter between (UT) 00:52:20 - 01:26:40. In enhanced XRT error circle (Beardmore et al, GCN 11188) we do not detect any object. The object at distance of 4" from the center of the enhanced XRT error circle (Beardmore et al, GCN 11188) in coordinates (J2000) RA =03 14 31.35 Dec= +30 58 44.8 with uncertainty of 1" is detected at magnitude R ~ 20 and upper limit of stacked image of R=21 (3 sigma). At present time we cannot confirm variability of the object. The finding chart can be found at http://grb.rssi.ru/GRB100902A/GRB100902A_R_Z600.jpg