MASTER OT J123123.61-043847.2 discovery inside LVC S191205ah error box

ATel #13335; T. Pogrosheva, V. Lipunov, V. Kornilov, E. Gorbovskoy, N. Tiurina, P. Balanutsa, V. Vladimirov, A. Kuznetsov, D. Vlasenko, D. Zimnukhov, K. Zhirkov, A. Chasovnikov, O. Gress, A. Gabovich, V. Senik (Lomonosov MSU), D. Buckley(SAAO), R. Rebolo, M. Serra(The Instituto de Astrofisica de Canarias), R. Podesta, C. Lopez, F. Podesta, C. Francile (OAFA), H. Levato(ICATE), N. M. Budnev, O. Ershova(ISU, API), A. Tlatov, D. Dormidontov(Kislovodsk Solar Station of the Pulkovo Observatory),V. Yurkov, Yu. Sergienko(Blagoveschensk ESU)
on 7 Dec 2019; 14:37 UT
Credential Certification: Nataly Tyurina (tiurina@sai.msu.ru)

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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

MASTER Global Robotic Net