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Three OTs of different types detected by MASTER

ATel #5374; D. Denisenko, P. Balanutsa, V. Lipunov, E. Gorbovskoy, N. Tiurina, V. Kornilov, N. Shatskiy, V. Chazov, A. Kuznetsov, V. Yecheistov, V. Vladimirov (Moscow State University, SAI), 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), A. Parkhomenko, A. Tlatov, D. Dormidontov, V. Senik (Kislovodsk solar station of the Pulkovo observatory RAS), P. Podvorotny, V. Shumkov, S. Shurpakov (MASTER team members), H. Levato, C. Saffe (ICATE), C. Mallamaci, C. Lopez and F. Podest (OAFA)
on 7 Sep 2013; 20:49 UT
Credential Certification: Vladimir Lipunov (lipunov2007@gmail.com)

Subjects: Optical, Cataclysmic Variable, Supernovae, Transient, Variables

MASTER OT J011539.70+381750.3 - new CV

MASTER-Amur auto-detection system discovered OT source at (RA, Dec) = 01h 15m 39.70s +38d 17m 50.3s on 2013-09-05.64799 UT. The OT unfiltered magnitude is 16.8m (limit 18.1m). The OT is seen in 8 images. We have reference image without OT on 2012-07-27.74843 UT with unfiltered m_lim=18.5.

The object is identical to the star USNO-B1.0 1282-0028758 (01 15 39.715 +38 17 51.39 B2=20.83 R2=18.37 I=N/A). It shows large variability between POSS-II plates: bright on 1989-09-07 Blue plate, faint on 1989-10-07 Red, not visible on 1991-10-03 Red and faint on 1995-08-22 Blue. Color-combined DSS finder chart is uploaded to http://master.sai.msu.ru/static/OT/J011539+381751-BRIR.jpg (10x10' FOV).

The OT has UV counterpart with two entries in GALEX catalogue: GALEX J011539.7+381751 (FUV=20.75+/-0.15 NUV=20.21+/-0.07) and GALEX J011539.6+381751 (FUV=19.42+/-0.19 NUV=19.47+/-0.10). There is nothing at this position in 1RXS, 2MASS, GCVS and AAVSO VSX. This area of sky in Andromeda is not covered by SDSS.

Object shows large variability in CRTS data with 5 outbursts to 17.6-17.7m. This region of sky was observed by Palomar/NEAT project on two nights. It was not visible on 2001 Oct. 05, but in bright outburst on 2002 Oct. 20. Comparison of combined NEAT images is uploaded to http://master.sai.msu.ru/static/OT/J011539+381751-NEAT.jpg

Based on the large amplitude of variability, UV detection and multiple previous outbursts we conclude that MASTER OT J011539.70+381750.3 is a very active cataclysmic variable (dwarf nova). Follow up observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/011539.70381750.3.png

MASTER OT J062719.22+152305.3 - flaring red dwarf

MASTER-Amur auto-detection system discovered OT source at (RA, Dec) = 06h 27m 19.22s +15d 23m 05.3s on 2013-09-06.80420 UT. The OT unfiltered magnitude is 15.7m (limit 17.2m). The OT is seen in 3 images. There is nothing on the sum of three reference images (total exposure 180 sec) on 2013-09-06.76106 UT (1 hr before) with unfiltered m_lim=17.6.

Object has faded by 0.6m (from 15.7 to 16.3) in 1.7 minutes between two 60-sec exposures starting at 19:09:09 and 19:20:50 UT. The OT is identical to the red star which shows large variability between two blue Palomar plates taken on 1955-11-10 and 1994-12-03. It is present in USNO catalogue as USNO-B1.0 1053-0111694 (06 27 19.216 +15 23 05.96 B1=19.38 R1=18.20 B2=N/A R2=18.65 I=16.63). Color-combined DSS finder chart is uploaded to http://master.sai.msu.ru/static/OT/J062719+152305-BRIR5x5.jpg (2x zoom).

There is an infrared counterpart 2MASS 06271919+1523052 (J=14.91+/-0.04 H=14.32+/-0.04 K=14.13+/-0.06). Color index J-K=0.78+/-0.07 corresponds to the red dwarf. There is nothing at this position in 1RXS, GCVS and AAVSO VSX. This area of sky in Gemini is not covered by CRTS, NEAT, SDSS and GALEX.

Based on the red color, amplitude of variability, short rise time and fast fading rate we suggest that MASTER OT J062719.22+152305.3 is a new flaring star of UV Ceti type. Follow up observations are encouraged. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/J062719.22152305.3.jpg

MASTER OT J073105.40+575610.8 - possible supernova

MASTER-Amur auto-detection system discovered OT source at (RA, Dec) = 07h 31m 05.40s +57d 56m 10.8s on 2013-09-06.81447 UT. The OT unfiltered magnitude is 16.7m (limit 18.1m). The OT is seen in 4 images. We have reference image without OT on 2012-10-20.73471 UT with unfiltered m_lim=18.9.

The OT is located 7" west and 11" south of the nucleus of the galaxy PGC 21194 = NVSS J073106+575624 (z=0.04245). This area of sky in Lynx is not covered by SDSS. Spectral observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/073105.40575610.8.png

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