TITLE: GCN CIRCULAR NUMBER: 17365 SUBJECT: GRB 150128A: MASTER OT detction during inspection DATE: 15/01/30 20:29:37 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs O.Gres, K.Ivanov, S.Yazev, N.M.Budnev, V.A.Poleshchuk Irkutsk State University E. Gorbovskoy, V. Lipunov, N.Tyurina, P.Balanutsa, D.Denisenko, A.Kuznetsov, V.Kornilov, D.Kuvshinov Lomonosov Moscow State University, Sternberg Astronomical Institute V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov Blagoveschensk Educational State University A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory V.Krushinsky, I.Zalozhnih, A. Popov Ural Federal University, Kourovka D.Buckley, S. Potter, A.Kniazev, M.Kotze South African Astronomical Observatory H. Levato and C. Saffe Instituto de Ciencias Astronomicas de la Tierra y del Espacio (ICATE), San Juan, Argentina C. Mallamacci, C. Lopez and F. Podest Observatorio Astronomico Felix Aguilar (OAFA), San Juan National University, Argentina MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Tunka was pointed to the GRB150128A 34 sec after notice time and 124 sec after trigger time at 2015-01-28 19:01:18 UT. We made several 20s alert exposures on the centre of first FERMI error box (ra=18 11 00 dec=+24 21 58 r=11.2). Than we start inspect survey inside this error box with average upper limit 18.9 mag. After more exact coordinates comes MASTER II robotic telescope located in Tunka was pointed on the centre of new FERMI error-box (ra=18 09 03 dec=+27 46 48 r=3.320000) 25 sec after notice time and 11821 sec after trigger time at 2015-01-28 22:16:15 UT. Than we continued inspect survey inside new error box with upper limit from 18 to 19. MASTER II robotic telescope located in Kislovodsk was starting inspect survey on the FERMI error-box (ra=18 09 03 dec=+27 46 48 r=3.3) 15569 sec after notice time and 27364 sec after trigger time at 2015-01-29 02:35:18 UT with average upper limit from 17.5 to 19. During the inspection of the error box of a long (more than 60 sec) multi-peak gamma-ray burst GRB 150128A (Fermi trigger 444164357, INTEGRAL SPI-ACS trigger 6874) MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 18h 01m 53.15s +25d 43m 23.5s on 2015-01-28.91546 UT (V.Shumkov et al., Atel 7010). The OT unfiltered magnitude is 16.6m (limit 18.6m). The OT is seen in 3 images. There is no minor planet at this place. We have reference image without OT on 2011-06-28.73624 UT with unfiltered magnitude limit 19.8m. For the description of Global MASTER Robotic Net see Lipunov et al., 2010, Advances in Astronomy, article id. 349171, pp. 1-7. ) MASTER-net coverage map available here: First error-box r=11.1d http://master.sai.msu.ru/static/GRB150128_net2.png Second error-box r= 3.3d http://master.sai.msu.ru/static/GRB150128_net.png This message may be cited. [GCN OPS NOTE(30jan15): The operator removed the redundnat "GRB" from the Subject-line and added the "A" suffix in two places in the body of the Circular.]