MASTER-IAC: dwarf nova outburst with ampl>5.4m

ATel #13003; V. Shumkov, A. Pozdnyakov, V. Lipunov (Lomonosov MSU), R. Rebolo, M. Serra (IAC), 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 MSU), R. Podesta, C. Lopez, F. Podesta, C. Francile (OAFA), H. Levato (ICATE), D. Buckley (SAAO), O. Gres, N. Budnev, O. Ershova (Irkutsk State University, API), A. Tlatov, D. Dormidontov (KSS of Pulkovo Observatory), V. Yurkov, A. Gabovich, Yu. Sergienko (BSPU)
on 8 Aug 2019; 08:05 UT
Credential Certification: Nataly Tyurina (tiurina@sai.msu.ru)

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MASTER OT J201544.38-063112.5 discovery - dwarf nova outburst with ampl>5.4m

MASTER-IAC auto-detection system ( Lipunov et al., "MASTER Global Robotic Net",Advances in Astronomy, 2010, 30L )

discovered OT source at (RA, Dec) = 20h 15m 44.38s -06d 31m 12.5s on 2019-08-07.98170 UT.
The OT unfiltered magnitude is 16.6m (limit 18.5m) =AT2019mwv .

The OT is seen in 2 images. There is no minor planet at this place.

We have reference image without OT on 2019-07-30.03325 UT with unfiltered magnitude limit 19.7m.

There was previous outburst in MASTER-Kislovodsk on 2014-07-24 23:12:22/07-25 00:04:34.132UT

There is GALEX source, no optial sources in DSS (USNO-B1 et al.), it mean 22m limit in history and more then 5.4m of current outburst amplitude (MASTER W calibrated by USNO-B1 B2,R2 of thousands field stars as W=0.2B+0.8R)
Spectral observations are required.

The discovery and reference images are available at:

http://master.sai.msu.ru/static/OT/201544.38-063112.5.png

MASTER OT J203813.00-244813.7 detection - current outburst with ampl>3.4m of Gaia18dqf/AT2018jhr

MASTER-SAAO auto-detection system discovered OT source at (RA, Dec) = 20h 38m 13.00s -24d 48m 13.7s on 2019-08-06.83090 UT with m_OT= 17.0m (mlim=19.5).
The OT is seen in 2 images.
We have image with m_OT=19.0 on 2019-06-10 22:09:06UT (MASTER-SAAO), and without OT on 2019-08-07 09:43:07UT (mlim=18.0, MASTER-OAFA) and on 2015-06-12.00361UT(mlim=20.4m).
Spectral observations are required.

http://master.sai.msu.ru/static/OT/203813.00-244813.7.png

MASTER Global Robotic Net