TITLE: GCN CIRCULAR NUMBER: 22246 SUBJECT: GRB 171212A/Swift J1935.7+2036: TSHAO optical observations DATE: 17/12/12 19:18:46 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Mazaeva (IKI), A. Pozanenko (IKI), I. Reva (FAPHI), M. Krugov (FAPHI), A. Kusakin (FAPHI), A. Volnova (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of GRB 171212A (Tohuvavohu et al., GCN 22243) with Zeiss-1000 1-m telescope of Tien Shan Astronomical Observatory starting on Dec. 12 (UT) 12:21:15. We took several images in R-filter. Within enhanced Swift-XRT error circle (Evans et al. GCN 22245) we do not detect any object. Preliminary photometry of initial combined images is following. Date UT start t-T0 Filter Exp. OT Err. ULim (mid, days) (s) 2017-12-12 12:21:15 0.01896 R 3*120 n/d n/d 20.0 2017-12-12 12:21:15 0.02728 R 13*120 n/d n/d 21.1 The photometry is based on several nearby USNO-B1.0 stars USNO-B.1_id R2 1105-0415742 17.60 1105-0415769 17.54 1105-0415805 16.38 1106-0408959 17.07 1105-0415666 16.91