Bright CV discovered by MASTER

ATel #4995; V. Yecheistov, D. Denisenko, V. Lipunov, E. Gorbovskoy, N. Tiurina, V. Kornilov, A. Belinski, N. Shatskiy, V. Chazov, A. Kuznetsov, P. Balanutsa, D. Zimnukhov (Moscow State University, SAI), V. Krushinsky, I. Zalozhnih, A. Popov, A. Bourdanov, A. Punanova (Ural Federal University), K. Ivanov, S. Yazev, N. Budnev, E. Konstantinov, O. Chuvalaev, V. Poleshchuk, O. Gress, A. Frolova, (Irkutsk State University), A. Parkhomenko, A. Tlatov, D. Dormidontov, V. Senik (Kislovodsk solar station of the Pulkovo observatory RAS), V. Yurkov, Y. Sergienko, D. Varda, E. Sinyakov (Blagoveshchensk Educational University), P. Podvorotny, V. Shumkov, S. Shurpakov (MASTER team members), H. Levato, C. Saffe (ICATE), C. Mallamaci, C. Lopez and F. Podest (OAFA)
on 20 Apr 2013; 11:32 UT
Credential Certification: Vladimir Lipunov (lipunov2007@gmail.com)

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MASTER OT J210736.73+340227.1 - new bright CV

MASTER-Amur auto-detection system discovered OT source at (RA, Dec) = 21h 07m 36.73s +34d 02m 27.1s on 2013-04-18.76816 UT. The OT unfiltered magnitude is 15.5m (limit 17.4m). The OT is seen in 6 images. We have unfiltered reference image with OT at 18.2m on 2012-08-08.70365 UT (magnitude limit 18.4m). The object was also observed by MASTER-Tunka on 4 nights reaching 15.1m on a single image obtained on 2011-08-08.61510 UT.

There is nothing at this position in 1RXS, GCVS and AAVSO VSX. This area of sky in Cygnus is not covered by SDSS, CRTS and NEAT. The variable is identical to the star USNO-B1.0 1240-0472261 (21 07 36.725 +34 02 28.07 B1=19.13 R1=17.61 B2=18.43 R2=18.04 I=17.40) aka USNO-A2.0 1200-17148414 (21 07 36.74 +34 02 28.0 R=17.9 B=18.5) and to the IR source 2MASS 21073673+3402280 (J=15.74+/-0.07 H=15.43+/-0.11 K=15.93+/-0.27). Color-combined (BRIR) finder chart is uploaded to http://master.sai.msu.ru/static/OT/J210736+340227-BRIR5x5.jpg

The archival light curve with many detections in the high state is not typical for dwarf novae. It is possible that MASTER OT J210736.73+340227.1 is a cataclysmic variable of VY Scl or AM Her type. Spectral confirmation is required to check for the presense of He II 4686 AA line. Photometric observations to search for the orbital period are also encouraged. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/210736.73340227.1.png

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