TITLE: GCN CIRCULAR NUMBER: 19775 SUBJECT: GRB 160804A: ISON/UAFO optical observations DATE: 16/08/05 15:40:06 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Mazaeva (IKI), E. Chornaya (UAFO, ISON), A. Matkin (UAFO), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of GRB 160804A (Marshall et al., GCN 19761) with SANTEL-650 (0.65m) telescope of UAFO/ISON-Ussuriysk observatory. We obtained several unfiltered images starting on August 04 (UT) 12:03:56. We clearly detected optical source reported by Breeveld et al. (GCN 19764), Tyurina et al. (GCN 19768), Malesani et al. (GCN 19770), Moskvitin et al. (GCN 19771), Xu et al. (GCN #19773) and Bolmer et al. (GCN 19774). Preliminary photometry of a combined image is following Date UT start t-T0 Filter Exp. OT Err. UL (mid, days) (s) 2016-08-04 12:03:56 0.46189 CR 60*120 19.90 0.27 21.6 Photometry is based on nearby SDSS DR9 stars SDSS-DR9_id R(Lupton) J144642.43+100147.7 18.068 J144642.15+100017.4 17.644 J144638.04+095917.6 17.971 J144635.67+095910.6 18.378 J144619.22+095958.1 16.677 J144616.60+100018.4 16.575 J144614.88+100001.4 16.544