TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5189 SUBJECT: GRB 060526: RTT150 optical observations DATE: 06/05/31 06:17:36 GMT FROM: Rodion Burenin at IKI, Moscow I. Khamitov (TUG), I. Bikmaev, N. Sakhibullin (KSU/AST), Z. Aslan (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.), R. Burenin, M. Pavlinsky, R. Sunyaev (IKI) report: We continue our observations of the optical counterpart of GRB060526 (Campana et al. GCN 5162; French & Jelinek GCN 5165; Rykoff et al. GCN 5166) with Russian-Turkish 1.5-m telescope (RTT150, Bakirlitepe,TUBITAK National Observatory, Turkey). A series of frames were taken on May 30. The afterglow is detected on combined images in both V and R bands. We estimate the following Rc magnitudes for the OT: t-t0 m_R err 104.05 23.14 0.09 Our Rc lightcurve can be found at: http://hea.iki.rssi.ru/grb/060526/lc_0530.jpg In combination with MDM 1.3-m observations (Halpern et al., GCN 5188) these data suggest that the OT light curve can not be fitted by a combination of power laws and contain several optical flares. This message may be cited.