TITLE: GCN CIRCULAR NUMBER: 25088 SUBJECT: LIGO/Virgo S190718y Global MASTER-Net observations report DATE: 19/07/18 16:16:57 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), 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 S190718y errorbox 1850 sec after trigger time at 2019-07-18 15:06:02 UT, with upper limit up to 18.4 mag. The observations began at zenit distance = 23 deg. The sun altitude is -18.6 deg. The galactic latitude b = -60 deg., longitude l = 98 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/ligo_1.php?id=10491 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 1880 | 2019-07-18 15:06:02 | MASTER-Amur | ( 20h 34m 43.42s , +32d 26m 26.69s) | C | 60 | 18.4 | 1968 | 2019-07-18 15:07:30 | MASTER-Amur | ( 20h 30m 10.98s , +32d 38m 06.07s) | C | 60 | 18.4 | 2057 | 2019-07-18 15:08:58 | MASTER-Amur | ( 20h 34m 43.58s , +32d 26m 25.35s) | C | 60 | 18.4 | 2145 | 2019-07-18 15:10:27 | MASTER-Amur | ( 20h 30m 11.11s , +32d 38m 07.77s) | C | 60 | 18.4 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.