GCN Circular 19605
E. Mazaeva (IKI), A. Kusakin (Fesenkov Astrophysical Institute), P. Minaev (IKI), 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 GRB 160625B (Dirirsa et al., GCN 19580; Burns et al. GCN 19581) with Zeiss-1000 (East) 1-m telescopes of Tien Shan Astronomical Observatory. We obtained several images in R filter starting on June 26 (UT) 19:39:18. We detect optical afterglow of GRB 160625B (Troja et al., GCN 19588; Oates et al., GCN 19589). Preliminary photometry of a combined image is following Date UT start t-T0 Filter Exp. OT Err. UL (mid, days) (s) 2016-06-26 19:39:18 0.91784 R 50*120 19.07 0.05 22.0 Photometry is based on nearby USNO-B1.0 stars USNO-B.1_id R2 0969-0608423 16.38 0969-0608416 16.28 0969-0608335 15.00 0969-0608366 16.05 0969-0608449 17.38 0969-0608443 16.78 0969-0608456 16.79 The GRB 160625B triggered Fermi LAT and GBM (Dirirsa et al., GCN 19580; Burns et al. GCN 19581), Konus-Wind (Svinkin et al. GCN 19604) and D. Kann (GCN 19579) reported about CALET and SPI-ACS/INTEGRAL trigger. A light curve of SPI-ACS/INTEGRAL can be found in http://grb.rssi.ru/GRB160625B/GRB160625B_API-ACS.png The SPI-ACS time profile of GRB 160625B consists of 3 episodes of total duration about 750 seconds and compatible with time profiles reported by GBM (Burns, GCN 19581) and Konus-Wind (Svinkin et al. GCN 19604).