TITLE: GCN CIRCULAR NUMBER: 26474 SUBJECT: LIGO/Virgo S191216ap: IceCube event: MASTER OF detection in GW and Neutrino error field DATE: 19/12/17 14:14:26 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov,F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov(Lomonosov Moscow State University, SAI, Physics Department), O.A. Gres, N.M. Budnev, O.Ershova (Irkutsk State University, API), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), V. Yurkov, A. Gabovich, Yu. Sergienko(Blagoveschensk Educational State University) R. Podesta, C.Lopez, F. Podesta, C.Francile(Observatorio Astronomico Felix Aguilar OAFA), H.Levato(Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE), R. Rebolo, M. Serra(The Instituto de Astrofisica de Canarias), D. Buckley(South African Astronomical Observatory), During a MASTER-net inspect of LIGO/Virgo S191216ap (Lipunov et al., GCN 26457) MASTER-Amur robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Blagoveshchensk State Pedagogical University) started inspect of the LIGO/Virgo S191216ap IceCube neutrino counterpart errorbox (GCN 26460,26463) 41727 sec after trigger time at 2019-12-17 09:17:25 UT, with upper limit up to 17.4 mag. Observations started at twilight. The observations began at zenith distance = 50 deg. The sun altitude is -16.2 deg. MASTER-Tunka robotic telescope located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the LIGO/Virgo S191216ap IceCube neutrino counterpart errorbox 44823 sec after trigger time at 2019-12-17 10:09:01 UT, with upper limit up to 19.0 mag. Observations started at twilight. The observations began at zenith distance = 50 deg. The sun altitude is -10.0 deg. MASTER OF J212806.11+023221.9s - Optical Flare known CV. MASTER-Tunka auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OF at (RA, Dec) = 21h 28m 06.11s +02d 32m 21.9s on 2019-12-17.43984 UT. This flash falls off with the position of the famous CV CSS 151110: 212806 + 023221 (U Gem type). The OT magnitude in 'C' filter is 17.0m (mlim18.3=). The OT is seen in 2 images. There is no minor planet at this place. We have reference image on 2010-08-29.64730 UT with unfiltered mlim= 18.8m. Spectral observations are required. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1228593 The observation and reduction will continue. The message may be cited.