TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3691 SUBJECT: GRB 050727: RTT150 optical observations DATE: 05/07/27 22:02:23 GMT FROM: Rodion Burenin at IKI, Moscow R. Burenin, A. Tkachenko, M. Pavlinsky, R. Sunyaev (IKI), I. Khamitov, Z. Aslan (TUG), U. Kiziloglu (METU), A. Alpar (SabUni), I. Bikmaev, N. Sakhibullin (KSU/AST) report: We observed the error box of GRB 050727 (Swift trigger No. 147918) with Russian-Turkish 1.5-m telescope (RTT150, Bakyrlytepe, TUBITAK National Observatory, Turkey). We made a set of 600s exposures in R, starting at 18:11 UT, July 27, i.e. about 11.7 hours after the burst. We found no variable sources brighter than approximately R=22.5. This message may be cited.