TITLE: GCN CIRCULAR NUMBER: 19470 SUBJECT: GRB 160525B: Mondy optical upper limit DATE: 16/05/26 18:08:31 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Mazaeva (IKI), E. Klunko (ISTP), A. Volnova (IKI), I. Korobtsev (ISTP), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of the GRB 160525B (Krimm et al., GCN 19459) with AZT-33IK telescope of Sayan observatory (Mondy) starting on May, 25 (UT) 15:54:47. We do not detect any source within enhanced Swift-XRT position (Beardmore et al., GCN 19463). Preliminary photometry of the combined image is following Date UT start t-T0 Filter Exp. UpperLimit (3 sigma) (mid, days) (s) 2016-05-25 15:54:47 0.29111 R 30*120 22.6 Photometry is based on nearby SDSS-DR9 stars, Lupton transformations into R: SDSS-DR9_id R(Lupton) J095742.79+511301.4 16.17 J095737.78+511402.4 16.43 J095736.76+511019.5 14.87 J095730.61+510914.1 17.74 J095737.35+510856.0 15.01