TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4081 SUBJECT: GRB051008: optical observation DATE: 05/10/10 23:03:53 GMT FROM: Alexei Pozanenko at IKI, Moscow V.Rumyantsev (CrAO), V.Biryukov (SAI, MSU), and A.Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: We have observed the GRB051008 error box (Marshall et al., GCN4069) with 2.6 m Shajn telescope of CrAO. The observation start on Oct. 8, 17:05:08 (UT), i.e 38 minutes after the burst onset. We found an optical source within XRT error circle (Perri et al., GCN4073) which is not present in DSS2 (R): RA(J2000) =13 31 29.98 Dec =+42 05 52.06 Preliminary photometry against of USNO A2.0 is R=21.4+-0.1. Finding chart of the optical source can be found at http://grb.rssi.ru/GRB051008/GRB051008_ZTSh_R.gif More detailed analysis and observations are in progress. No optical source is detected in the place of radio source (Cameron et al., GCN4074). This message can be cited.