TITLE: GCN CIRCULAR NUMBER: 26379 SUBJECT: LIGO/Virgo S191205ah: MASTER OT detection DATE: 19/12/07 18:23:33 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, T.Pogrosheva, 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 OT J123123.61-043847.2 discovery - bright OT inside LVC S191205ah error box MASTER started inspect of LVC 191205ah (NS+BH, 385 +/-164 Mpc LVC GCN 26350 , Lipunov et al. GCN 26353) error-box 60 sec after notice time. MASTER-Kislovodsk auto-detection system Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L discovered OT source at (RA, Dec) = 12h 31m 23.61s -04d 38m 47.2s on 2019-12-07.06641 UT. The OT unfiltered magnitude is 17.9m +-0.1 (automatic reduction),m_limit=19.5m. The OT is seen in 3 images. There is no minor planet at this place. We have reference image without OT on 2018-12-19 01:45:26 UT with unfiltered magnitude limit 20.1m, the nearest in time reference image is on 2019-11-27 06:16:51UT with unfiltered mlim=18.8. There is no OT in MASTER-Amur,-Tunka, -Kislovodsk, -IAC, -Tavrida, -SAAO, -OAFA database since 2009 There is no any sources in VIZIER database inside 5", it meas 22m POSS limit and amplitude of current outburst more then 4m in the second scenario of its nature (as CV) Spectral observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/123123.61-043847.2.png Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/ligo_1.php?id=10979 The observation and reduction will continue. The message may be cited.