TITLE: GCN CIRCULAR NUMBER: 19935 SUBJECT: GRB 160910A: TSHAO optical observations DATE: 16/09/18 20:03:32 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Mazaeva (IKI), A. Kusakin (Fesenkov Astrophysical Institute), I. Reva (Fesenkov Astrophysical Institute), A. Volnova (IKI), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of the GRB 160910A (Veres et al., GCN 19901; Racusin et al., GCN 19902) with Zeiss-1000 (East) 1-m telescope of Tien Shan Astronomical Observatory. We obtained several images in R filter starting on Sep., 12 and Sep., 15. We clearly detected optical afterglow (Ugarte Postigo et al., GCN 19907; Malesani et al., GCN 19908; Lipunov et al., GCN 19914). Preliminary photometry of the afterglow is following Date UT start t-T0 Filter Exp. OT UpLim (3 sigma) (mid, days) (s) 2016-09-12 14:43:02 1.92176 R 27*120 19.96 +/- 0.08 21.7 2016-09-15 14:31:13 4.91356 R 27*120 21.70 +/- 0.30 21.7 Photometry is based on nearby SDSS-DR9 stars used in GCN 19919 (Mazaeva et al.).