MASTER-SAAO: bright Dwarf Nova outburst and new Dwarf Nova

ATel #7521; V. Shumkov, D. Denisenko, V. Lipunov, E. Gorbovskoy (Lomonosov MSU), D. Buckley (SAAO), S. Antipin, N. Tiurina, A. Kuznetsov, V. Kornilov, V. Chazov, V. Vladimirov (Lomonosov Moscow State University, Sternberg Astronomical Institute), O. Gress, N. Budnev, K. Ivanov, S. Yazev, V. Poleshchuk (Irkutsk State University), S. Potter, A. Kniazev, M. Kotze (The South African Astronomical Observatory), A. Tlatov, D. Dormidontov, V. Senik, A. Parkhomenko (Kislovodsk solar station of the Pulkovo observatory RAS), V. Krushinsky, I. Zalozhnih, A. Popov, A. Bourdanov (Ural Federal University), Yu. Sergienko, V. Yurkov, A. Gabovich (Blagoveschensk State Educational University), S. Shurpakov (MASTER-Team)
on 17 May 2015; 16:13 UT
Credential Certification: Nataly Tyurina (tiurina@sai.msu.ru)

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MASTER OT J222112.37-195823.3 discovery - new Dwarf Nova in outburst, Ampl>3.5m, no known source in VIZIER

MASTER-SAAO auto-detection system ( Lipunov et al., Advances in Astronomy, MASTER Global Robotic Net, 2010 ) discovered OT source at (RA, Dec) = 22h 21m 12.37s -19d 58m 23.3s on 2015-05-17.06566 UT. The OT unfiltered magnitude is 17.9m (the limit is 19.8m).

There are 4 images with OT. There is no minor planet at this place. There are 2 images with m_OT=19.2 on 2015-04-01.153UT (one of previous outburst?)

There is no known source in VIZIER database, no sources in CRTS survey at this coordinates, so the amplitude of this outburst is more than 3.5m.

The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/222112.37-195823.3.png

Spectral observations are required.

MASTER OT J222049.51-740240.9 discovery - very bright Dwarf Nova outburst, Ampl>3.5

MASTER-SAAO auto-detection system discovered OT source at (RA, Dec) = 22h 20m 49.51s -74d 02m 40.9s on 2015-05-16.96532 UT. The OT unfiltered magnitude is 15.1m (the limit is 20.2m).

There are 4 images with current outburst of this Dwarf Nova. There are 3 images of previous outburst on 2015-01-20.820, 2015-01-20.824, 2015-01-20.829 with unfiltered m_OT=16.8 in MASTER-SAAO database. There are images on 2015-01-19.821UT with m_OT=17.9, and on 2015-03-15.111 with m_OT=17.9m . There is 0159-0267933 USNO-B1 star with B2=18.72, R2=18.83. So the amplitude is more then 3.5.

The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/222049.51-740240.9.png

Spectral observations are required.

MASTER Global Robotic Net