TITLE: GCN CIRCULAR NUMBER: 26584 SUBJECT: LIGO/Virgo S191225aq: Global MASTER-Net observations report DATE: 19/12/25 22:16:28 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, D. Cheryasov (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 S191225aq errorbox 38 sec after notice time and 270 sec after trigger time at 2019-12-25 22:01:45 UT, with upper limit up to 18.6 mag. The observations began at zenith distance = 36 deg. The sun altitude is -33.9 deg. The galactic latitude b = -21 deg., longitude l = 206 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/ligo_1.php?id=11133 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 295 | 2019-12-25 22:01:45 | MASTER-SAAO | (05h 19m 19.58s , +03d 40m 37.1s) | C | 50 | 18.1 | 376 | 2019-12-25 22:02:56 | MASTER-SAAO | (05h 19m 19.48s , +03d 41m 14.5s) | C | 70 | 18.4 | 473 | 2019-12-25 22:04:27 | MASTER-SAAO | (05h 19m 19.46s , +03d 39m 58.8s) | C | 80 | 18.5 | 589 | 2019-12-25 22:06:09 | MASTER-SAAO | (05h 19m 23.26s , +03d 41m 18.9s) | C | 110 | 16.7 | 715 | 2019-12-25 22:08:05 | MASTER-SAAO | (05h 17m 59.29s , -03d 06m 39.6s) | C | 130 | 18.6 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.