TITLE: GCN CIRCULAR NUMBER: 24236 SUBJECT: LIGO/Virgo S190426c Global MASTER-Net observations report DATE: 19/04/26 16:39:46 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, V.Kornilov, D.Kuvshinov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.V.Chazov, D. Vlasenko Lomonosov Moscow State University, Sternberg Astronomical Institute, Moscow State University A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory K. Ivanov, O. Gres, N.M. Budnev, S. Yazev, O. Chuvalaev, V. Poleshchuk Irkutsk State University V. Yurkov, A. Gabovich, Yu. Sergienko Blagoveschensk Educational State University, Blagoveschensk R. Podesta, Carlos Lopez and F. Podesta Observatorio Astronomico Felix Aguilar (OAFA) Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias D. Buckley, S. Potter, A. Kniazev, M. Kotze South African Astronomical Observatory 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 S190426c errorbox 3232 sec after trigger time at 2019-04-26 16:15:47 UT, with upper limit up to 18.4 mag. The observations began at zenit distance = 117 deg. The sun altitude is -25.7 deg. MASTER-Tunka robotic telescope located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the LIGO/Virgo S190426c errorbox 3803 sec after trigger time at 2019-04-26 16:25:18 UT, with upper limit up to 19.5 mag. The observations began at zenit distance = 125 deg. The sun altitude is -24.9 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=10199 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 3323 | 2019-04-26 16:15:47 | MASTER-Amur | ( 2h 50m 29.91s , +85d 53m 31.28s) | C | 180 | 18.3 | 3556 | 2019-04-26 16:19:40 | MASTER-Amur | ( 14h 14m 37.41s , +85d 56m 38.95s) | C | 180 | 18.1 | 3768 | 2019-04-26 16:23:13 | MASTER-Amur | ( 0h 25m 31.78s , +85d 27m 16.37s) | C | 180 | 18.4 | 3893 | 2019-04-26 16:25:18 | MASTER-Tunka | ( 22h 27m 30.53s , +83d 55m 49.49s) | C | 180 | 19.5 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.