TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3493 SUBJECT: GRB 050525: RTT150, Optical observations DATE: 05/05/27 15:44:50 GMT FROM: Irek Khamitov at TUG Z. Aslan, I. Khamitov, T. Ozisik, K. Uluc (TUG), U. Kiziloglu (METU), I. Bikmaev, N. Sakhibullin (KSU/AST), A. Alpar (SabUni), A.Yaskovich, R.Burenin, M. Pavlinsky, R. Sunyaev (IKI), report: We have observed the field of OT of GRB 050525 (Rykoff et al, GCN3465) with 2k*2k Andor CCD attached to the Russian-Turkish 1.5-m telescope (Bakirlitepe, Turkey) in VRc bands. We made series of 5*90s exposures in V, starting at 00:22UT May 26, and 20*60s exposures in Rc, starting at 01:18 UT May 26. On 20 co-added R-images we clearly see the OT at the position RA = 18:32:32.57 (2000.0), DEC=+26:20:22.5 (2000.0) based on the USNO-B1 catalog, its uncertainty is about 0.1 arcsec. We estimate m_R magnitude of OT using USNO-B1 as 21.76+/-0.17 corresponding to the midtime of 25.5 hours after the burst. This message may be cited.