TITLE: GCN CIRCULAR NUMBER: 19092 SUBJECT: GRB 160225.81/FERMI Trigg 478121069: MASTER OT J095503.19-355149.4 detection DATE: 16/02/26 16:15:54 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs D.Buckley, S. Potter, M.Kotze South African Astronomical Observatory N.Tyurina, E. Gorbovskoy, V. Lipunov, V.Kornilov, P.Balanutsa, A.Kuznetsov, D.Kuvshinov Lomonosov Moscow State University, Sternberg Astronomical Institute, Moscow State University A.Gabovich, V.Yurkov, Yu.Sergienko, D.Varda Blagoveschensk Educational State University, Blagoveschensk K.Ivanov, N.M.Budnev, O.Gres, V.A.Poleshchuk Irkutsk State University A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory R. Rebolo, M. Serra-Ricart, N. Lodieu, G. Israelian The Instituto de Astrofisica de Canarias MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in SAAO was pointed to the GRB160225.81 (FERMI GBM TRIGGER NUM 478121069) 33 sec after notice time and 77 sec after trigger time at 2016-02-25 19:25:42 UT. On our first (20s exposure) set we do not found OTs FERMI initial error-box (ra=10 21 21 dec=-28 35 59 r=4.8 degreeas ) brighter then 15.3 . After 2 hours we started inspection new error box and found MASTER OT J095503.19-355149.4 . This source are not inside initial images. MASTER-SAAO auto-detection system discovered OT source at (RA, Dec) = 09h 55m 03.19s -35d 51m 49.4s on 2016-02-25.89505 UT. Errors are ~0.7 arcsec. The OT unfiltered magnitude is 18.1m (limit 19.3m). The OT is seen in 3 images. There is no minor planet at this place. We have reference image without OT on 2015-01-17.92448 UT with unfiltered magnitude limit 19.7m. Spectral observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/095503.19-355149.4.png The OT position inside last error box (very close to center) is available at http://master.sai.msu.ru/static/OT/MAP095503.19-355149.4.png The message may be cited.