TITLE: GCN CIRCULAR NUMBER: 10207 SUBJECT: GRB 091127: optical observations DATE: 09/11/29 12:56:34 GMT FROM: Alexei Pozanenko at IKI, Moscow M. Andreev, A. Sergeev (Terskol Branch of Institute of Astronomy), A. Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: We observed the optical afterglow (Smith et al. GCN 10192) of the Swift GRB 091127 (Troja et al. GCN 10191) with the Z-600 telescope of Mt.Terskol observatory in R-filter on Nov 28. In a combined images we clearly detect the afterglow. The photometry is based on the reference star used in GCN 10205 (the star #0710-0025176 of the USNO B1 catalog, assuming R2=14.02): T0+ Filter, Exposure, mag. (d) (s) 0.7981 R 10x180 18.60 +/- 0.10 0.9141 R 10x180 18.90 +/- 0.15 The photometry confirms the a global decay slope of ~0.8 within the first day after burst (Xu et al. GCN 10205).