TITLE: GCN CIRCULAR NUMBER: 18151 SUBJECT: MASTER OT inside bright ESO240-010 galaxy detection during FERMI trigger GRB150816.83 inspection DATE: 15/08/17 17:57:20 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs D.Buckley, S. Potter, A.Kniazev, M.Kotze South African Astronomical Observatory E.Popova, V. Lipunov, E. Gorbovskoy, N.Tyurina, V.Kornilov, P.Balanutsa, A.Kuznetsov, D.Kuvshinov, Lomonosov Moscow State University, Sternberg Astronomical Institute K.Ivanov, O.Gres, N.M.Budnev, S.Yazev, Irkutsk State University R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias A. Tlatov, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory V.Yurkov, Yu.Sergienko, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk V.Krushinski, I.Zalozhnih Ural Federal University, Kourovka Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) Claudio Mallamaci, Carlos Lopez and Federico Podest Observatorio Astronomico Felix Aguilar (OAFA) MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in SAAO was pointed to the GRB150816.83 24 sec (FERMI Trigger Num = 461447392) after notice time and 89 sec after trigger time at 2015-08-16 19:51:18 UT. The 5-sigma upper limit on our first (60s exposure) set is about 16.4 and grows to 19.0 mag (unfiltered) during survey. MASTER-SAAO auto-detection system discovered OT source (MASTER OT J233743.22-473039.3)at (RA, Dec) = 23h 37m 43.22s -47d 30m 39.3s on 2015-08-17.18201 UT (Popova et al., Atel 7919). The OT unfiltered magnitude is 16.3 m (limit 18.7 m). The OT is seen in 2 images. There is no minor planet at this place. We have reference image without OT on 2015-08-07.98051 UT with unfiltered (= 0.2B+0.8R with respect to 1000 USNO B stars) magnitude limit 20.5m. Spectral observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/233743.22-473039.3.png The message may be cited.