TITLE: GCN CIRCULAR NUMBER: 25831 SUBJECT: LIGO/Virgo S190924h: Global MASTER-Net observations report DATE: 19/09/24 03:29:16 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 S190924h errorbox 1759 sec after notice time and 2222 sec after trigger time at 2019-09-24 02:55:48 UT, with upper limit up to 18.9 mag. The observations began at zenit distance = 73 deg. The sun altitude is -19.9 deg. MASTER-IAC robotic telescope located in Spain (IAC Teide Observatory) started inspect of the LIGO/Virgo S190924h errorbox 2641 sec after notice time and 3104 sec after trigger time at 2019-09-24 03:10:30 UT, with upper limit up to 15.2 mag. The observations began at zenit distance = 85 deg. The sun altitude is -47.3 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=10835 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 2312 | 2019-09-24 02:55:48 | MASTER-SAAO | (09h 19m 04.417s , -05d 52m 26.63s) | C | 180 | 17.3 | 2531 | 2019-09-24 02:59:27 | MASTER-SAAO | (09h 05m 19.012s , -07d 52m 15.64s) | C | 180 | 18.9 | 2914 | 2019-09-24 03:05:49 | MASTER-SAAO | (08h 33m 39.336s , +15d 54m 26.45s) | C | 180 | 16.7 | 3194 | 2019-09-24 03:10:30 | MASTER-IAC | (08h 27m 34.435s , +15d 53m 04.11s) | P| | 180 | 15.2 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.