TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3718 SUBJECT: GRB 050730: RTT150 optical observations DATE: 05/07/31 23:27:15 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 optical afterglow of GRB 050730 (Holland et al., GCN #3704) with Russian-Turkish 1.5-m telescope (RTT150, Bakyrlytepe, TUBITAK National Observatory, Turkey). Observations were made under partially clouded sky. We obtained a set of 180s images in BVRI filters. Object was clealy detected in I and R and marginally in V. Using reference star from Holman et al. (GCN #3716) we estimate R=21.24+-0.17 at 19:01 UT, July 31. This message may be cited.