TITLE: GCN CIRCULAR NUMBER: 17956 SUBJECT: V404 Cyg: MASTER Swift, Integral alert observations DATE: 15/06/23 12:56:37 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs K.Ivanov, O.Gres, N.M.Budnev, S.Yazev, O.Chuvalaev, V.A.Poleshchuk Irkutsk State University V.Krushinski, I.Zalozhnih, A. Popov Ural Federal University, Kourovka E. Gorbovskoy, V. Lipunov, N.Tyurina, V.Kornilov, P.Balanutsa, A.Kuznetsov, E.Popova, D.Kuvshinov, Lomonosov Moscow State University, Sternberg Astronomical Institute Rafael Rebolo, Miquel Serra, N. Lodieu, G. Israelian, L. Suarez-Andres (The Instituto de Astrofisica de Canarias) D.Buckley, S. Potter, A.Kniazev, M.Kotze South African Astronomical Observatory A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) Carlos Lopez, Claudio Mallamaci and Federico Podest Observatorio Astronomico Felix Aguilar (OAFA) MASTER-Tunka was pointed to the V404 Cyg 36 sec after notice time , 164 sec after Swift trigger N 643949 (Barthelmy et. al GCN #17929 )time at 2015-06-15 18:34:23 UT. MASTER-Ural was pointed to the V404 Cyg 22 sec after notice time , 150 sec after swift trigger N 643949 (Barthelmy et. al GCN #17929 ) time at 2015-06-15 18:34:09 UT. The 5 MASTER (http://observ.pereplet.ru , Lipunov et al.2010, Advances in Astronomy, vol. 2010, pp. 1-7) robotic twin telescopes every clear night observed V404 Cyg by Integral alerts sending ( Erik Kuulkers, ATel #7695). Site DATE UT Start DATE UT Finish Exp Duration Polarisation Tunka 2015-06-15 18:34:23 2015-06-15 19:33:48 40 1.0 h |- 2 Ural 2015-06-15 18:34:09 2015-06-15 19:42:09 10 1.1 h /\ 3 IAC 2015-06-18 00:09:07 2015-06-18 05:26:19 190 5.2 h |- 4 Tunka 2015-06-18 14:45:47 2015-06-18 19:44:43 96 5.0 h |- 5 Kisl 2015-06-18 18:50:29 2015-06-19 00:34:30 176 5.4 h |- 6 SAAO 2015-06-18 22:19:33 2015-06-19 04:42:30 282 6.5 h \/ 7 Tunka 2015-06-19 14:21:47 2015-06-19 19:12:1 90 4.9 h |- 8 Kisl 2015-06-19 18:08:38 2015-06-19 22:02:20 108 3.1 h |- 9 SAAO 2015-06-19 21:26:05 2015-06-20 04:41:46 318 7.3 h \/ 10 Tunka 2015-06-20 16:07:32 2015-06-20 19:33:50 59 3.5 h |- 11 Kisl 2015-06-20 17:55:38 2015-06-20 20:24:19 36 3.5 h |- 12 SAAO 2015-06-20 21:59:20 2015-06-21 04:43:37 320 6.7 h \/ 13 Tunka 2015-06-21 19:04:51 2015-06-21 19:36:31 26 0.5 h |- 14 SAAO 2015-06-21 21:16:36 2015-06-22 04:43:06 320 7.5 h \/ 15 Kisl 2015-06-21 21:30:56 2015-06-22 00:36:31 78 3.0 h |- 16 SAAO 2015-06-22 21:15:28 2015-06-23 04:43:58 260 7.5 h \/ We have more than 2400 mesuarments now; The preliminary photometry of MASTER-Net telescopes are available at http://master.sai.msu.ru/static/OT/MASTERV404.jpg We see > 8% linear polarisation ( that corresponds to ATEL #7678 , ATEL #7674). We defenitely detect polatizations variability at time scale ~10 minutes. The Ural light curves (upper fig.) VS polarization (below) data are available at http://master.sai.msu.ru/static/v404syg_tu.png The observations are continued. The message may be cited.