TITLE: GCN CIRCULAR NUMBER: 26903 SUBJECT: LIGO/Virgo S200128d: Global MASTER-Net observations report DATE: 20/01/28 02:34:56 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 S200128d errorbox 37 sec after notice time and 322 sec after trigger time at 2020-01-28 02:25:33 UT, with upper limit up to 18.4 mag. The observations began at zenith distance = 41 deg. The sun altitude is -18.1 deg. MASTER-IAC robotic telescope located in Spain (IAC Teide Observatory) started inspect of the LIGO/Virgo S200128d errorbox 71 sec after notice time and 356 sec after trigger time at 2020-01-28 02:26:07 UT, with upper limit up to 18.1 mag. The observations began at zenith distance = 68 deg. The sun altitude is -71.2 deg. The galactic latitude b = 11 deg., longitude l = 332 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/ligo_1.php?id=11283 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 353 | 2020-01-28 02:25:33 | MASTER-SAAO | (15h 32m 49.48s , -42d 18m 49.4s) | C | 60 | 18.4 | 392 | 2020-01-28 02:26:07 | MASTER-IAC | (04h 23m 02.77s , +35d 36m 33.1s) | P| | 70 | 18.1 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.