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GCN Circular 25897

LIGO/Virgo S190930t and S190930s: MASTER optical observation and optical transient
2019-10-01T13:32:24Z (5 years ago)
Vladimir Lipunov at Moscow State U/Krylov Obs <>
V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tiurina, F.Balakin,P.Balanutsa,A.Kuznetsov, V.Vladimirov, D. Vlasenko, I.Gorbunov,
D.Zimnukhov,V.Senik, T.Pogrosheva, K.Pozdnyakov, A.Chasovnikov, V.Topolev,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 Global Robotic Net (, Lipunov et al.,2010,Advances in Astronomy, vol.2010, 30L)
started inspect of LIGO/Virgo S190930t (LVC GCN 25876) 
146 sec after trigger time at 2019-09-30 14:36:33 UT (Lipunov et al. GCN 25875)
and observed it at MASTER-Amur, -Tunka, -Kislovods, -Tavrida, -SAAO, 
-OAFA), see real-time coverage map at

During this inspect we found OT, but there are 2 PanSTARR sources in 1.6" and 1.8",
and the blue one can be CV, but
it is also inside LIGO/Virgo S190930s (LVC GCN 25871, Lipunov et al. GCN25870)
and we need a Spectrum

MASTER 205329.99+224421.2 discovery

MASTER-IAC auto-detection system discovered OT source at
(RA, Dec) = 20h 53m 29.99s +22d 44m 21.2s on 2019-09-30.90192 UT.
The OT unfiltered magnitude is 18.1m (limit 19.3m).

The OT is seen in 3 images. There is no minor planet at this place.

We have reference image without OT on 2016-09-23.93716 UT with unfiltered magnitude limit 20.1m.

Spectral observations are required.

The discovery and reference images are available at:
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