MASTER-Kislovodsk: possible Dwarf Nova flare

ATel #7463; V. Shumkov, V. Lipunov, E. Gorbovskoy, S. Antipin, N. Tiurina, P. Balanutsa, V. Kornilov, A. Kuznetsov, V. Chazov, E. Popova, V. Vladimirov (Lomonosov Moscow State University, SAI), D. Buckley, S. Potter, A. Kniazev, M. Kotze (The South African Astronomical Observatory), N. Budnev, K. Ivanov, O. Gress, S. Yazev, V. Poleshchuk (Irkutsk State University), 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 30 Apr 2015; 22:28 UT
Credential Certification: Nataly Tyurina (tiurina@sai.msu.ru)

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MASTER 185737.57+684156.9 discovery - Dwarf Nova flare, Ampl>3.2m

MASTER-Kislovodsk auto-detection system ( Lipunov et al., Advances in Astronomy, MASTER Global Robotic Net, 2010 ) discovered OT source at (RA, Dec) = 18h 57m 37.57s +68d 41m 56.9s on 2015-04-28.96310 UT.

The OT unfiltered magnitude is 18.4m (limit 19.2m).

The OT is seen in 3 images on 2015-04-28(18.4m) and on 3 images on 2015-04-26(18.3m). There is no minor planet at this place.

We have reference image without OT on 2010-05-13.93987 UT with 20.6 unfiltered magnitude limit, and 300 reference images since 2009 in MASTER-Kislovodsk and MASTER-Tunka databases.
CRTS covered this area, but didn't see any sources befor.

Spectral observations are required.

The discovery and reference images are available at:http://master.sai.msu.ru/static/OT/185737.57684156.9_3.png

Global MASTER Robotic Net