TITLE: GCN CIRCULAR NUMBER: 25875 SUBJECT: LIGO/Virgo S190930t: Global MASTER-Net observations report DATE: 19/09/30 15:25:13 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 S190930t errorbox 146 sec after trigger time at 2019-09-30 14:36:33 UT, with upper limit up to 17.8 mag. The observations began at zenit distance = 53 deg. The sun altitude is -41.8 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=10861 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 236 | 2019-09-30 14:36:33 | MASTER-Amur | (21h 37m 57.259s , +04d 14m 22.62s) | C | 180 | 17.2 | 446 | 2019-09-30 14:40:02 | MASTER-Amur | (21h 27m 36.298s , +02d 14m 13.90s) | C | 180 | 17.8 | 666 | 2019-09-30 14:43:42 | MASTER-Amur | (21h 26m 50.955s , +00d 13m 52.57s) | C | 180 | 17.6 | 1073 | 2019-09-30 14:50:30 | MASTER-Amur | (21h 13m 54.694s , +04d 13m 40.66s) | C | 180 | 17.8 | 1287 | 2019-09-30 14:54:03 | MASTER-Amur | (21h 11m 37.617s , +02d 13m 43.23s) | C | 180 | 17.6 | 1924 | 2019-09-30 15:04:40 | MASTER-Amur | (21h 27m 38.532s , +02d 13m 57.91s) | C | 180 | 17.3 | 2138 | 2019-09-30 15:08:14 | MASTER-Amur | (21h 35m 39.297s , +02d 13m 55.29s) | C | 180 | 17.4 | 2349 | 2019-09-30 15:11:45 | MASTER-Amur | (21h 26m 53.129s , +00d 13m 45.37s) | C | 180 | 17.3 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.