TITLE: GCN CIRCULAR NUMBER: 20195 SUBJECT: GRB 161117A: MASTER-OAFA (Argentina) prompt OT observations DATE: 16/11/18 12:54:01 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs R.Podesta, C.Lopez, F. Podesta Observatorio Astronomico Felix Aguilar (OAFA) , National University of San Juan, Argentina H. Levato, C. Saffe Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE), San Juan, Argentina V. Lipunov, E. Gorbovskoy, V.Kornilov, D.Kuvshinov, N.Tyurina, A.V.Krylov, I.Gorbunov, P.Balanutsa, A.Kuznetsov, V.V.Chazov Lomonosov Moscow State University, Sternberg Astronomical Institut of MSU K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk Irkutsk State University V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov Blagoveschensk Educational State University, Blagoveschensk A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Senik Kislovodsk Solar Station of the Pulkovo Observatory D.Buckley, S. Potter, A.Kniazev, M.Kotze South African Astronomical Observatory R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias MASTER-OAFA robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in OAFA was pointed to the GRB161117A 22 sec after notice time and 31 sec after trigger time at 2016-11-17 01:36:13 UT. On our first (10s exposure) set we found optical transient within SWIFT error box (Cummings et al., 20179) at the Swift UVOT position (Cummings et al., 20179; Daniele Malesani et al. GCN 20180;). The OT magnitude ~17.0 . The 5-sigma upper limit has been about 17.5 mag After several minutes OT disapear and apear against around 01 35 56 UT with unfiltered (red) magnirude ~ 18.0 (cf D'Avanzo et al., GCN 20181;). The observations started at zenit distance = 42 degrees, galaxy latitude b = -46 degree. The moon (91 % bright part) below the horizon (The altitude of the Moon is -1 degree ). The sun altitude is -25.6 degree. The object can be observed till 2016-11-17 05:44:35 UT. The message may be cited.