TITLE: GCN CIRCULAR NUMBER: 25944 SUBJECT: Swift GRB191004.75: Global MASTER-Net OT detection DATE: 19/10/04 18:26:11 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, V.Kornilov, D.Kuvshinov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, F. Balakin Lomonosov Moscow State University, Sternberg Astronomical Institute, Moscow State University D. Buckley, S. Potter, A. Kniazev, M. Kotze South African Astronomical Observatory K. Ivanov, O. Gres, N.M. Budnev, S. Yazev, O. Chuvalaev, V. Poleshchuk Irkutsk State University A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory V. Yurkov, A. Gabovich, Yu. Sergienko Blagoveschensk Educational State University, Blagoveschensk R. Podesta, Carlos Lopez and F. Podesta Observatorio Astronomico Felix Aguilar (OAFA) Hugo Levato 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-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the GRB191004.75 25 sec after notice time and 43 sec after trigger time at 2019-10-04 18:07:45 UT. On our first (10s exposure) set we found 1 optical transient within Swift error-box (ra=31.7208 dec=-36.9319 r=0.05) brighter than 23. T-Tmid Date Time Expt. Ra Dec Mag ---------|---------------------|-------|-----------------|-----------------|------- 48 2019-10-04 18:07:45 10 (02h 06m 40.526s , -36d 56m 00.41s) 15.11 The 5-sigma upper limit has been about 23mag The message may be cited.