TITLE: GCN CIRCULAR NUMBER: 25512 SUBJECT: LIGO/Virgo S190828l Global MASTER-Net observations report DATE: 19/08/28 10:43:38 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-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) started inspect of the LIGO/Virgo S190828l errorbox 1606 sec after notice time and 3022 sec after trigger time at 2019-08-28 07:45:31 UT, with upper limit up to 16.6 mag. The observations began at zenit distance = 84 deg. The sun altitude is -41.4 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=10739 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 3113 | 2019-08-28 07:45:31 | MASTER-OAFA | (09h 43m 48.516s , -49d 48m 33.56s) | C | 180 | 14.8 | 6722 | 2019-08-28 08:45:40 | MASTER-OAFA | (09h 37m 17.654s , -51d 55m 37.22s) | C | 180 | 16.6 | 6943 | 2019-08-28 08:49:22 | MASTER-OAFA | (09h 37m 19.541s , -51d 55m 31.84s) | C | 180 | 15.8 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.