MASTER: optical transients with amplitude more then 5.6 and 3.8m

ATel #13364; E. Gorbovskoy, O. Gress, V. Lipunov (Lomonosov MSU), D. Buckley (SAAO), R. Rebolo, M. Serra (IAC), V. Kornilov, N. Tiurina, P. Balanutsa, I. Gorbunov, E. Minkina, A. Kuznetsov, V. Vladimirov, T. Pogrosheva, D. Vlasenko, D. Zimnukhov, D. Cheryasov, V. Senik, A. Chasovnikov, K. Zhirkov, V. Shumkov(Lomonosov MSU), R. Podesta, C. Lopez, F. Podesta, C. Francile (OAFA), H. Levato(ICATE), D. Buckley(SAAO), O. A. Gres, N. M. Budnev, O. Ershova(ISU, API), A. Tlatov, D. Dormidontov(Kislovodsk Solar Station of the Pulkovo Observatory),V. Yurkov, A. Gabovich, Yu. Sergienko(Blagoveschensk ESU)
on 23 Dec 2019; 18:31 UT
Credential Certification: Nataly Tyurina (tiurina@sai.msu.ru)

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MASTER OT J164104.64-792602.9 discovery - OT(possibly dwarf nova) with ampl>5.6m
AT2019xjj

MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L )
discovered OT source at (RA, Dec) = 16h 41m 04.64s -79d 26m 02.9s on 2019-12-20.03532 UT.
The OT unfiltered magnitude is 16.4m (mlim=18.5).
The OT is seen in 3 images. There is no minor planet at this place. There is no any sources in VIZIEr database at this place, it means 22m POSS limit in history and more then 5.6m of current outburst amplitude.
We have reference image on 2017-01-26.09664 UT with unfiltered mlim = 19.9m.
Spectral observations are required.
The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/164104.64-792602.9.png

MASTER OT J073917.36-415646.7 discovery - outburst with ampl>3.8m
AT2019xjo

MASTER-SAAO auto-detection system discovered OT source at (RA, Dec) = 07h 39m 17.36s -41d 56m 46.7s on 2019-12-20.98491 UT.
The OT unfiltered magnitude is 18.2m (mlim=19.3).
The OT is seen in 2 images. There is no minor planet at this place.
We have reference image on 2015-04-12.86979 UT with unfiltered mlim= 20.0m.There is only GSC2.3.2 source(with blue jmag=18.4 during previous outburst in 1978.171y, so current outburst amplitude is more then 3.8m (POSS limits in history).
Spectral observations are required.
The discovery and reference images are available at:http://master.sai.msu.ru/static/OT/073917.36-415646.7.png

Current outbursts:

1) MASTER OT J152804.66-673720.4 (AAVSO) with m_OT=17.0 on 2019-12-20 01:44:43.367UT.
AT2019xjk

2) MASTER OT J094414.86-633913.7 (also known as ASASSN-19adk) with m=14.7 on 2019-12-20 21:33:16.628

MASTER Global Robotic Net