MASTER: optical transients

ATel #7786; P. Balanutsa, V. Vladimirov, V. Lipunov, E. Gorbovskoy (Lomonosov MSU), D. Buckley (SAAO), N. Samus (INASAN), N. Tiurina, V. Kornilov, A. Kuznetsov, I. Gorbunov, V. Chazov, D. Vlasenko (Lomonosov Moscow State University, Sternberg Astronomical Institute), D. Buckley, S. Potter, M. Kotze (South African Astronomical Observatory), R. Rebolo, M. Serra-Ricart, N. Lodieu, G. Israelian, L. Suarez-Andres (The Instituto de Astrofisica de Canarias), A. Tlatov, D. Dormidontov, V. Senik (Kislovodsk Solar Station of the Pulkovo Observatory), O. Gress, N. M.Budnev, K. Ivanov (Applied Physics Institute, Irkutsk State University), V. Krushinski, I. Zalozhnykh (Ural Federal University)
on 11 Jul 2015; 01:15 UT
Credential Certification: Nataly Tyurina (tiurina@sai.msu.ru)

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MASTER OT J182527.58+662528.8 - possible dwarf nova outburst with Ampl>4.3mag

MASTER-Kislovodsk auto-detection system ( Lipunov et al., Advances in Astronomy, MASTER Global Robotic Net, 2010 ) discovered OT source at (RA, Dec) = 18h 25m 27.58s +66d 25m 28.8s on 2015-07-08.84251 UT.
The OT unfiltered magnitude is 17.7m (the limit is 19.7m).

The OT is seen in 3 images. There is no minor planet at this place. We have reference image without OT on 2015-06-11.90839 UT with 20.3 unfiltered magnitude limit.
There is EO0550-0141828 star (APM-North catalogue) with Bmag=22.02. So we can suggest the dwarf nova outburst with Ampl>4.3mag.

Spectral observations are required.
The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/182527.58662528.8.png

MASTER OT J202151.88-455950.3 - possible dwarf nova outburst with Ampl>3.3mag

MASTER-SAAO auto-detection system discovered OT source at (RA, Dec) = 20h 21m 51.88s -45d 59m 50.3s on 2015-07-08.89427 UT.
The OT unfiltered magnitude is 17.8m (limit 18.8m).

The OT is seen in 4 images. There is no minor planet at this place. We have reference image without OT on 2015-04-22.08853 UT with unfiltered magnitude limit 20.8m.
There is USNO-B1 star with R2=21.14 (previous minimum), I=18.31, J=16.293(WISE), GALEX NUV=22.113.So, we can suggest the dwarf nova outburst with Ampl>3.3mag

Spectral observations are required.
The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/202151.88-455950.3.png

MASTER Global Robotic Net