TITLE: GCN CIRCULAR NUMBER: 20309 SUBJECT: GRB 161219B: ISON/Terskol optical observations DATE: 16/12/20 21:25:52 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Mazaeva (IKI), A. Mokhnatkin (KIAM), A. Pozanenko (IKI), A. Volnova (IKI), I. Molotov (KIAM) report on behalf of larger GRB follow-up collaboration: We observed the field of GRB 161219B (Swift trigger 727541; D'Ai, GCN 20296) with K-800 (0.8m) telescope of ISON/Terskol observatory starting on December, 19 (UT) 18:57:51, i.e. about 9 minutes after GRB onset. We obtained several unfiltered images of 30 s exposure. The optical afterglow (D'Ai et al., GCN 20296; Kruehler et al., GCN 20299; Guidorzi et al., GCN 20300; Martin-Carrillo et al., GCN 20305) is clearly visible in separate images. Preliminary light curve of the afterglow can be found in http://grb.rssi.ru/GRB161219B/GRB161219B_161219_K800.png Photometry is based on nearby USNO-B1.0 stars USNO-B.1_id R2 0631-0120570 13.78 0632-0119151 14.86 0632-0119187 14.03 0632-0119198 15.05 0632-0119218 14.66 0631-0120752 14.81