TITLE: GCN CIRCULAR NUMBER: 20075 SUBJECT: GRB 161017A: Lomonosov Gamma Ray and MASTER Optical prompt observations DATE: 16/10/18 16:23:33 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.A.Sadovnichy, Lomonosov Moscow State University M.I.Panasyuk, S.I.Svertilov, A.V.Bogomolov, V.V.Bogomolov, N.L.Dzhioeva, A.M.Amelushkin, V.O.Barinova, A.F.Iyudin, V.V.Kalegaev, D.Nguen, V.L. Petrov, I.V.Yashin, P.S.Kazarian Physics Department, Skobel`tsyn Institute of Nuclear Physics, Moscow State V. Lipunov, E.S. Gorbovskoy, N.Tyurina, D.Kuvshinov, M.Panchenko, A.Kuznetsov, V.G.Kornilov, P. Balanutsa, E.Popova Lomonosov Moscow State University, Sternberg Astronomical Institute V.Yurkov, A.Gabovich, Yu.Sergienko Blagoveschensk Educational State University, Blagoveschensk N.M.Budnev, K.Ivanov, O.Gres, O.Chuvalaev, V.A.Poleshchuk, S.Yazev Irkutsk State University R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias I. Park, J. Lee, S. Jeong Department of Physics, Sungkyunkwan University, Seobu-ro, Jangangu, Suwonsi, Korea At 17:52:17 UT on 17 Sep 2016, the Lomonosov BDRG Gamma-ray Burst Monitor (http://lomonosov.sinp.msu.ru/en/scientific-equipment-2/bdrg ) triggered GRB 161017A (E. Troja et al.,, GCN 20064). GRB 161017A has several peaks LC, total duration ~100s,the energy range 70-300 keV. The light curve is available at http://master.sai.msu.ru/static/Lomonosov/GRB161017A_BDRG2.png More information will be available at: http://lomonosov.sinp.msu.ru/category/results/observation-gamma-ray-bursts MASTER-Amur robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Blagoveschensk was pointed to the GRB161017A 21 sec after notice time and 47 sec after Swift trigger time at 2016-10-17 17:52:38 UT in two polarizations. On our first (10s exposure) set we marginally found optical transient at Yurkov et al. (GCN 20063) and Troja et al. (GCN 20064) position. The 5-sigma upper limit has been about 14.5 mag . The OT was became brighter up to maximum at 3-4 set . The observations made on zenit distance = 53 degrees, galaxy latitude b = 47 degree. The moon (96 % bright part) is 50 degrees above the horizon. The distance between moon and object is 87 The sun altitude is -37.8 degree. MASTER-Tunka robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Tunka (Baykal lake) was pointed to the GRB161017.74 75 sec after notice time and 103 sec after trigger time at 2016-10-17 17:53:34 UT. On our second (20s exposure) set we haven`t found optical transient within SWIFT error-box (ra=09 31 03 dec=+43 08 31 r=0.050000). The 5-sigma upper limit has been about 12.5 mag. The observations made on zenit distance = 65 degrees, galaxy latitude b = 47 degree. The moon (96 % bright part) is 50 degrees above the horizon. The distance between moon and object is 87 degrees. The sun altitude is -45.9 degrees. The low mahnitude limit because dense fog due to Irkut (Famost Sibirian river) evaporation. We imaged OT late. MASTER-IAC robotic telescope (MASTER-Net: http://observ.pereplet.ru) located at Teide Observatory (Tenerife, Canary, Spain) was pointed to the GRB161017A 32942 sec after trigger time at 2016-10-18 03:00:53 UT. On our first (180s exposure) set we found optical transient on coaded images. The 5-sigma upper limit has been about 17.8 mag The observations made on zenit distance = 69 degrees, galaxy latitude b = 47 degrees. The moon (94 % bright part) is 75 degrees above the horizon. The distance between moon and object is 82 degrees. The sun altitude is -54.1 degree. Our preliminary photometry is next: Time Tstart Tmid Expt Site Filter Mag eMag Filter Mag eMag 17:52:38 47 52 10 MASTER-Amur P/ 15.69 1.0 P\ 15.46 1.0 17:53:07 71 76 10 MASTER-Amur P/ 14.05 0.3 P\ 13.99 0.3 17:53:03 96 106 20 MASTER-Amur P/ 13.87 0.2 P\ 13.63 0.2 17:54:03 131 146 30 MASTER-Amur P/ 13.90 0.3 P\ 13.80 0.3 17:54:46 175 195 40 MASTER-Amur P/ 14.34 0.3 P\ 14.34 0.3 17:55:41 229 254 50 MASTER-Amur P/ 15.03 0.4 P\ 17:56:46 295 325 60 MASTER-Amur P/ 14.91 0.4 P\ 14.91 0.4 17:58:12 381 540 240 MASTER-Amur P/ 15.88 0.4 P\ 16.03 0.4 18:05:20 809 889 160 MASTER-Tunka P| 15.64 0.2 03:00:53 32942 33464 900 MASTER-IAC C 18.62 0.2 03:19:17 34046 34587 900 MASTER-IAC C 18.60 0.2 03:38:01 35170 35726 900 MASTER-IAC C 18.62 0.2 03:57:26 36335 36885 900 MASTER-IAC C 18.68 0.2 Preliminary OT light curve is available at http://master.sai.msu.ru/static/GRB161017A.png The message may be cited.