TITLE: GCN CIRCULAR NUMBER: 25989 SUBJECT: Swift GRB191011.19: Global MASTER-Net OT detection DATE: 19/10/11 04:50:49 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, V.Kornilov, D.Kuvshinov, N.Tyurina, P.Balanutsa, A.Kuznetsov, A.V. Krylov, I. Gorbunov, D. Vlasenko, F. Balakin Lomonosov Moscow State University, Sternberg Astronomical Institute, Moscow State University 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) 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 K. Ivanov, O. Gres, N.M. Budnev, S.Yazev, O. Chuvalaev, V. Poleshchuk Irkutsk State University D. Buckley, S. Potter, A. Kniazev, M. Kotze South African Astronomical Observatory R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias MASTER-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) was pointed to the GRB191011.19 14 sec after notice time and 34 sec after trigger time at 2019-10-11 04:36:30 UT. On our 3-th (30s exposure) set , obtained 148 sec after tigger time at 2019-10-11 04:38:25 UT, we found 1 optical transient within Swift error-box (ra=44.7208 dec=-27.845 r=0.05) brighter than 15.7. T-Tmid Date Time Expt. Ra Dec Mag ---------|---------------------|-------|-----------------|-----------------|------- 163 2019-10-11 04:38:25 30 (02h 58m 48.339s , -27d 51m 48.55s) 16.26 The OT has irregular early time behaviour since 410.7 till 643.2 seconds after the trigger. The 5-sigma upper limit has been about 15.7mag The message may be cited.