TITLE: GCN CIRCULAR NUMBER: 19947 SUBJECT: GRB 160925A/MASTER optical transient: Mondy optical observations DATE: 16/09/27 12:34:06 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Mazaeva (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), A. Volnova (IKI), I. Korobtsev (ISTP) report on behalf of larger GRB follow-up collaboration: We observed the field of the Fermi GRB 160925A (trigger #496473540) with AZT-33IK telescope of Sayan observatory (Mondy) starting on Sep., 26 (UT) 14:38:09. We obtained several images in R-filter. We clearly detected optical transient (Lipunov et al., GCN 19938; Guidorzi et al., GCN 19939). Preliminary photometry of the transient is following Date UT start t-T0 Filter Exp. OT UpLim (3 sigma) (mid, days) (s) 2016-09-26 14:38:09 0.88014 R 30*120 16.06+/-0.03 23.0 Photometry is based on nearby USNO-B1.0 stars USNO-B1.0 R2 0750-0813972 16.86 0750-0813954 17.70 0750-0813947 17.78