TITLE: GCN CIRCULAR NUMBER: 3492 SUBJECT: GRB050525a: optical upper limits DATE: 05/05/27 14:01:46 GMT FROM: Vasilij Rumjantsev at CrAO V.Rumyantsev (CrAO), G. Kornienko, A. Erofeeva, (UAPhO), A.Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: We have observed the refined error box (Cummings et al., GCN 3449) of the Swift GRB050525a (Band et al., GCN 3466) with 0.4m telescope of Ussuriysk Astrophysical Observatory (UAPhO), and AT-64 telescope of CrAO on May, 25. We do not detect OT found by Rykoff et al., (GCN 3465). Upper limits of unfiltered stacked images calibrated against of R USNO-A2.0 are following: Mean time Exposure Limiting mag. May 25 (UT) (s) 13:59 7x60 15.9 19:38 40x60 19.5 The message may be cited.