Two New CVs detected by MASTER

ATel #5348; S. Shurpakov, D. Denisenko, V. Lipunov, E. Gorbovskoy, P. Balanutsa, N. Tiurina, V. Kornilov, A. Belinski, N. Shatskiy, V. Chazov, A. Kuznetsov, V. Yecheistov (Moscow State University, SAI), A. Parkhomenko, A. Tlatov, D. Dormidontov, V. Senik (Kislovodsk solar station of the Pulkovo observatory RAS), V. Yurkov, Y. Sergienko, D. Varda, E. Sinyakov, A. Gabovich (Blagoveshchensk Educational University), K. Ivanov, S. Yazev, N. Budnev, E. Konstantinov, O. Chuvalaev, V. Poleshchuk, O. Gress, A. Frolova (Irkutsk State University), V. Krushinsky, I. Zalozhnih, A. Popov, A. Bourdanov (Ural Federal University), P. Podvorotny, V. Shumkov (MASTER team members), H. Levato, C. Saffe (ICATE), C. Mallamaci, C. Lopez and F. Podest (OAFA)
on 31 Aug 2013; 13:47 UT
Credential Certification: Vladimir Lipunov (lipunov2007@gmail.com)

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MASTER OT J203937.54+213904.7 - new CV

MASTER-Amur auto-detection system discovered OT source at (RA, Dec) = 20h 39m 37.54s +21d 39m 04.7s on 2013-08-28.50743 UT. The OT unfiltered magnitude is 15.8m (limit 18.0m). The OT is seen in 12 images. There is no minor planet at this place. We have reference image without OT on 2012-06-21.69505 UT with unfiltered magnitude limit 18.6m. Previous outburst to 15.2m was observed by MASTER-Amur eight months ago, on 2012-12-23.363 and 23.395 UT.

The OT at quiescence is identical to the star USNO-B1.0 1116-0521901 (R.A.=20 39 37.587, Decl.=+21 39 06.34, pmRA=18 pmDE=4 R1=19.25 B2=20.31 R2=20.15). Color-combined (BRIR) DSS image is uploaded to http://master.sai.msu.ru/static/OT/J203937+213904-BRIR.jpg (field of view 10'x10').

The object also has an infrared counterpart 2MASS 20393757+2139060 (J=15.33+/-0.05, H=15.47+/-0.12, K=15.47+/-0.17) likely detected in outburst on 2000-05-01 images. There is nothing at this position in 1RXS, GCVS and AAVSO VSX. This area of sky in Vulpecula is not covered by GALEX, SDSS, CRTS and Palomar/NEAT.

Based on the amplitude of variability (~4.5m) we suggest that MASTER OT J203937.54+213904.7 is a new cataclysmic variable (dwarf nova in outburst). Follow up observations are encouraged. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/203937.54213904.7.jpg

MASTER OT J235503.22+420010.2 - new CV

MASTER-Kislovodsk auto-detection system discovered OT source at (RA, Dec) = 23h 55m 03.22s +42d 00m 10.2s on 2013-08-30.86859 UT. The OT unfiltered magnitude is 16.1m (limit 18.1m). The OT is seen in 5 images. There is no minor planet at this place. We have reference image without OT on 2012-12-11.67444 UT with unfiltered magnitude limit 20.0m. The OT was not present on 2013-07-26.951 UT MASTER-Kislovodsk image (m_lim=17.9).

There is a faint blue star within 1" of the OT on the digitized Palomar plates. It is present in GSC 2.3.2 with coordinates 23 55 03.273 +42 00 10.38 and jmag=21.53 and in USNO-B catalogue as USNO-B1.0 1320-0570515 (R.A.=23 55 03.146, Decl.=+42 00 09.92, B2=21.51). Color-combined (BRIR) DSS image is uploaded to http://master.sai.msu.ru/static/OT/J235503+420010-BRIR5x5.jpg

There is nothing at this position in 1RXS, GALEX, 2MASS, GCVS and AAVSO VSX. This area of sky in Andromeda is not covered by SDSS. No previous outbursts were detected by Catalina Sky Survey and by Palomar/NEAT.

Based on the amplitude of variability (~5.5m) we suggest that MASTER OT J235503.22+420010.2 is a new cataclysmic variable, most likely dwarf nova of SU UMa (UGSU) type in superoutburst. Follow up observations are encouraged. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/235503.22420010.2.png

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