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Two Cataclysmic Variables discovered by MASTER

ATel #6187; D. Denisenko, V. Lipunov, E. Gorbovskoy, N. Tiurina, P. Balanutsa, V. Kornilov, N. Shatskiy, V. Chazov, A. Kuznetsov, V. Vladimirov, V. Yecheistov (Moscow State University, SAI), A. Parkhomenko, A. Tlatov, D. Dormidontov, V. Senik (Kislovodsk Solar Station of Pulkovo Observatory), 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), 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 30 May 2014; 18:13 UT
Credential Certification: Nataly Tyurina (tiurina@sai.msu.ru)

Subjects: Optical, Cataclysmic Variable, Transient

Referred to by ATel #: 6325

MASTER OT J185624.15+400311.8 - new CV in Kepler field

MASTER-Kislovodsk auto-detection system discovered OT source at (RA, Dec) = 18h 56m 24.15s +40d 03m 11.8s on 2014-05-29.94169 UT. The OT unfiltered magnitude is 18.3m (limit 20.0m). The OT is seen in 3 images. There is no minor planet at this place. We have reference image without OT on 2010-11-16.66414 UT with unfiltered magnitude limit 19.1m.

The OT at quiescence is identical to the star SDSS J185624.13+400311.7 (u=22.22 g=21.91 r=21.64 i=21.10 z=20.50) = USNO-A2.0 1275-10539524 (18 56 24.17 +40 03 12.1 R=18.6 B=18.5) = USNO-B1.0 1300-0309422 (18 56 24.128 +40 03 11.85 pmRA=-6 pmDE=-4 B1=19.60 R1=18.70 B2=19.90 R2=N/A I=N/A). Color-combined DSS finder chart is uploaded to http://master.sai.msu.ru/static/OT/J185624+400311-BRIR5x5.jpg (2x zoom). The star was obviously in outburst on the 1st epoch Palomar plates taken on 1951-09-02.

The star was included into Kepler Input Catalogue as KIC 4903085. This is the 5th CV discovered by MASTER inside the Kepler field (see ATel #6071 and references therein). It has two entries in the Kepler-INT Survey differing by ~2m: KIS J185624.15+400311.8 (g=22.09 r=21.23 i=20.47) and KIS J185624.13+400311.7 (g=19.59 r=19.29 i=18.83).

There is nothing at this position in 1RXS, 2MASS, GCVS and AAVSO VSX. This area of sky in Lyra is not covered by GALEX. MASTER OT J185624.15+400311.8 is likely a new cataclysmic variable (dwarf nova). Follow up observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/191841.98444914.5.png

MASTER OT J200357.07-183211.3 - new CV

MASTER-Kislovodsk auto-detection system discovered OT source at (RA, Dec) = 20h 03m 57.07s -18d 32m 11.3s on 2014-05-29.96318 UT. The OT unfiltered magnitude is 15.6m (limit 19.0m). The OT is seen in 6 images. There is no minor planet at this place. We have reference image without OT on 2014-05-22.95990 UT with unfiltered magnitude limit 19.2m.

The OT at quiescence is identical to the blue star USNO-A2.0 0675-34815640 (20 03 57.10 -18 32 11.1 R=18.1 B=18.6) = USNO-B1.0 0714-0797682 (20 03 57.090 -18 32 10.87 B1=18.59 R1=18.21 B2=18.83 R2=18.63 I=17.91). Color-combined DSS finder chart is uploaded to http://master.sai.msu.ru/static/OT/J200357-183211-JRIR5x5.jpg (2x zoom).

The object has an UV counterpart GALEX J200357.0-183210 (FUV=20.33+/-0.23 NUV=20.49+/-0.20). There is nothing at this position in 1RXS, 2MASS, GCVS and AAVSO VSX. This area of sky in Sagittarius is not covered by SDSS. Mount Lemmon Survey light curve of MLS 200357.1-183211 shows two previous outbursts to 15.9m on 2006-07-21 and to 15.8m on 2010-07-05.

Based on the blue color and amplitude of variability MASTER OT J200357.07-183211.3 is a new cataclysmic variable, likely a dwarf nova of UGSU (SU UMa) type in outburst. Follow up observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/200357.07-183211.3.jpg

List of Optical Transients discovered by MASTER

Global MASTER Robotic Net