New CV in Kepler field discovered by MASTER

ATel #6071; P. Balanutsa, D. Denisenko, V. Lipunov, E. Gorbovskoy, N. Tiurina, V. Kornilov, N. Shatskiy, V. Chazov, A. Kuznetsov, V. Vladimirov, V. Yecheistov (Moscow State University, SAI), K. Ivanov, S. Yazev, N. Budnev, E. Konstantinov, O. Chuvalaev, V. Poleshchuk, O. Gress (Irkutsk State University), V. Yurkov, Y. Sergienko, D. Varda, E. Sinyakov, A. Gabovich (Blagoveshchensk Educational University), A. Parkhomenko, A. Tlatov, D. Dormidontov, V. Senik (Kislovodsk Solar Station of Pulkovo Observatory), V. Krushinsky, I. Zalozhnih, A. Popov, A. Bourdanov (Ural Federal University), P. Podvorotny, V. Shumkov, S. Shurpakov (MASTER team members), H. Levato, C. Saffe (ICATE), C. Mallamaci, C. Lopez, F. Podest (OAFA)
on 14 Apr 2014; 21:21 UT
Credential Certification: Nataly Tyurina (tiurina@sai.msu.ru)

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MASTER OT J191841.98+444914.5 - new CV

MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 19h 18m 41.98s +44d 49m 14.5s on 2014-04-13.72677 UT. The OT unfiltered magnitude is 16.8m (limit 18.0m). The OT is seen in 4 images. There is no minor planet at this place. We have reference image without OT on 2012-09-10.62603 UT with unfiltered magnitude limit 19.4m. There was a previous brighter outburst to 15.2m in MASTER-Tunka database on 2010-10-14.859 and 2010-10-14.890 UT (see the corresponding image).

The OT at quiescence is identical to the blue star USNO-B1.0 1348-0328932 (19 18 42.042 +44 49 13.05 B1=19.56 R1=N/A B2=16.57 R2=19.19 I=N/A). The star was in outburst on the POSS-II blue plate taken on 1990 July 18. Color-combined DSS finder chart is uploaded to http://master.sai.msu.ru/static/OT/J191842+444914-BRIR.jpg (10'x10' FOV). The object has an UV counterpart GALEX J191842.0+444912 (NUV=19.09+/-0.03).

There is nothing at this position in 1RXS, 2MASS, GCVS and AAVSO VSX. This area of sky in Cygnus is not covered by SDSS and Catalina Sky Survey. Based on the blue color and amplitude of variability (~4m), MASTER OT J191841.98+444914.5 is a new cataclysmic variable, most likely a dwarf nova in outburst. Follow up observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/191841.98444914.5.png

The star was included into Kepler Input Catalogue as KIC 8683556. This is the 4th CV discovered by MASTER inside the Kepler field (see also ATel #4926, ATel #5574 and ATel #6024). Checking the Kepler database for the previous outbursts is encouraged.

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