TITLE: GCN CIRCULAR NUMBER: 27129 SUBJECT: LIGO/Virgo S200219ac: Global MASTER-Net observations report DATE: 20/02/19 12:49:23 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, D. Cheryasov (Lomonosov Moscow State University, SAI, Physics Department), 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), 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) 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 S200219ac errorbox 101 sec after notice time and 9677 sec after trigger time at 2020-02-19 12:25:32 UT, with upper limit up to 17.2 mag. The observations began at zenith distance = 53 deg. The sun altitude is -34.0 deg. The galactic latitude b = -84 deg., longitude l = 224 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/ligo_1.php?id=11346 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 9707 | 2020-02-19 12:25:32 | MASTER-Amur | (12h 46m 13.37s , +51d 52m 37.4s) | C | 60 | 17.2 | 9787 | 2020-02-19 12:26:51 | MASTER-Amur | (12h 46m 13.51s , +51d 53m 32.6s) | C | 60 | 17.2 | 9866 | 2020-02-19 12:28:11 | MASTER-Amur | (12h 46m 20.20s , +51d 52m 30.7s) | C | 60 | 17.1 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.