TITLE: GCN CIRCULAR NUMBER: 25694 SUBJECT: LIGO/Virgo S190910d Global MASTER-Net observations report DATE: 19/09/10 01:57:31 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-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the LIGO/Virgo S190910d errorbox 157 sec after trigger time at 2019-09-10 01:28:56 UT, with upper limit up to 19.0 mag. The observations began at zenit distance = 43 deg. The sun altitude is -41.6 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=10782 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 248 | 2019-09-10 01:28:56 | MASTER-SAAO | (04h 49m 50.020s , -67d 59m 39.61s) | C | 180 | 17.8 | 482 | 2019-09-10 01:32:50 | MASTER-SAAO | (02h 57m 56.175s , -08d 53m 48.13s) | C | 180 | 18.0 | 512 | 2019-09-10 01:34:05 | MASTER-SAAO | (04h 59m 49.012s , -45d 34m 00.88s) | C | 90 | 19.0 | 668 | 2019-09-10 01:36:27 | MASTER-SAAO | (04h 48m 33.843s , -45d 27m 12.28s) | C | 120 | 18.1 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.