TITLE: GCN CIRCULAR NUMBER: 21320 SUBJECT: GRB 170705A: TShAO optical observations DATE: 17/07/11 17:39:03 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Volnova (IKI), E. Mazaeva (IKI), A. Pozanenko (IKI), A. Kusakin (Fesenkov Astrophysical Institute), I. Reva (Fesenkov Astrophysical Institute) report on behalf of larger GRB follow-up collaboration: We observed the field of the Swift GRB 170705A (Starling et al. GCN 21289) which is also detected by GBM/Fermi and Konus-Wind (Bissaldi et al., GCN 21297; Svinkin et al., GCN 21299) with Zeiss-1000 1-m telescope of Tien Shan Astronomical Observatory on July 6-8. We took several images in R-filter. The optical afterglow of GRB 170705A (Starling et al. GCN 21289, Lipunov et al. GCN 21291, Butler et al. GCN 21293, Emery et al. GCN 21294; Ugarte Postigo et al. GCN 21298) is visible in a combined image on July 6, and upper limit only for July 7-8. Preliminary photometry of the afterglow is following. Date UT start t-T0 Filter Exp. OT Err. UL (mid, days) (s) (3 sigma) 2017-07-06 16:28:29 1.61411 R 38*180 20.67 0.24 21.1 2017-07-07 17:30:55 2.63106 R 13*180 n/d n/d 20.6 2017-07-07 17:30:55 3.10501 R 34*180 n/d n/d 21.1 Photometry is based on nearby SDSS DR9 stars listed in GCN 21300.