TITLE: GCN CIRCULAR NUMBER: 20367 SUBJECT: GRB170104.78 MASTER-Net OT detection DATE: 17/01/05 03:48:04 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs D.Buckley, S. Potter, A.Kniazev, M.Kotze South African Astronomical Observatory V. Lipunov, E. Gorbovskoy, V.Kornilov, D.Kuvshinov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.V.Chazov Lomonosov Moscow State University, Sternberg Astronomical Institute, Moscow State University A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Senik Kislovodsk Solar Station of the Pulkovo Observatory V.Yurkov, A. Gabovich, Yu.Sergienko Blagoveschensk Educational State University, Blagoveschensk K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk Irkutsk State University R. Podesta, Claudio Mallamaci, Carlos Lopez and Federico Podesta Observatorio Astronomico Felix Aguilar (OAFA) Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in SAAO was pointed to the GRB170104.78 921 sec after notice time and 921 sec after trigger time at 2017-01-04 18:53:57 UT. On our first (180s exposure) set we found 1 optical transient within Swift error-box (ra=352.496 dec=-29.9997 r=0.1) brighter then 18.4. T-Tmid Date Time Expt. Ra Dec Mag ---------|---------------------|-------|-----------------|-----------------|------- 1011 2017-01-04 18:53:57 180 (23h 30m 07.38s , -30d 00m 32.4s) 16.91 The 5-sigma upper limit has been about 18.4mag The message may be cited.