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Flaring Star, Maser Flare and New CV discovered by MASTER

ATel #6477; P. Balanutsa, D. Denisenko, V. Lipunov, E. Gorbovskoy, N. Tiurina, V. Kornilov, 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 16 Sep 2014; 11:23 UT
Credential Certification: Nataly Tyurina (tiurina@sai.msu.ru)

Subjects: Optical, Cataclysmic Variable, Transient, Variables

MASTER OT J081855.19+300252.6 - flaring red dwarf

MASTER-Kislovodsk auto-detection system discovered OT source at (RA, Dec) = 08h 18m 55.19s +30d 02m 52.6s on 2014-09-12.00837 UT. The OT unfiltered magnitude is 15.3m (limit 18.4m). The OT is seen in 3 images fading to 15.7m on 2014-09-12.01054 UT (100 minutes later). We have follow-up image without OT on 2014-09-12.07841 UT with unfiltered magnitude limit 17.3m.

The OT at quiescence is identical to the red star SDSS J081855.22+300253.4 (g=20.74 r=19.23 i=17.33 z=16.20) = 2MASS J08185522+3002538 (J=14.54 H=13.93 K=13.55). There is nothing at this position in 1RXS, GCVS and AAVSO VSX.

Based on the red color, amplitude of variability and rapid fading, MASTER OT J081855.19+300252.6 is a new variable of UV Ceti type. Follow up observations are encouraged. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/081855.19300252.6.jpg

MASTER OT J213253.43+213159.7 - flare of OH maser

MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 21h 32m 53.43s +21d 31m 59.7s on 2014-09-14.73235 UT. The OT unfiltered magnitude is 14.8m (limit 18.8m). The OT is seen in 8 images. We have reference image without OT on 2011-07-07.70198 UT with unfiltered m_lim=19.4.

There is a red star within 2" on Palomar plates and in USNO-B catalog: USNO-B1.0 1115-0565128 (21 32 53.74 +21 32 00.3 R1=19.96 R2=18.77 I=16.11). Color-combined DSS finder chart is uploaded to http://master.sai.msu.ru/static/OT/J213253+213159-BRIR.jpg (10'x10' FOV). The object is identical to the infrared source 2MASS J21325363+2132006 (J=8.77 H=6.60 K=5.02) = WISE J213253.62+213200.5 (W1=4.40 W2=2.76 W3=0.67 W4=-0.93) = IRAS 21305+2118. It was observed as a maser, but is not included as a variable star in GCVS or AAVSO VSX.

This area of sky in Pegasus is not covered by SDSS. Catalina Sky Survey light curve of CSS J213254.0+213158 (blend with a star 6" to the east of the OT) shows two previous bright episodes.

Follow up observations are required. MASTER detection and reference images are available at: http://master.sai.msu.ru/static/OT/213253.43213159.7.png

MASTER OT J213809.25+212824.0 - new CV

MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 21h 38m 09.25s +21d 28m 24.0s on 2014-09-14.77706 UT. The OT unfiltered magnitude is 17.2m (limit 19.0m). The OT is seen in 6 images. We have reference image without OT on 2011-07-07.70198 UT with unfiltered m_lim=19.4.

The OT at quiescence is identical to the blue star SDSS J213809.26+212823.8 (u=21.19 g=21.00 r=20.66 i=20.64 z=20.50) = USNO-B1.0 1114-0563330 (B1=19.78 B2=20.86). Color-combined DSS finder chart is uploaded to http://master.sai.msu.ru/static/OT/J213809+212824-BRIR.jpg (10'x10' FOV).

The object has an UV counterpart GALEX J213809.2+212824 (FUV=18.94 NUV=18.63). There is nothing at this position in 2MASS, GCVS and AAVSO VSX. The OT is located 12" from the eclipsing variable BW Peg (range 14.1-15.2, P=1.58392d). There are 39 Palomar/NEAT images of this area on 14 nights from 2000 Aug. 26 to 2003 Aug. 13. The star was in outburst on 2001 Sep. 22 and 26 and at quiescence on other nights.

Based on the blue color and outburst amplitude, MASTER OT J213809.25+212824.0 is a new cataclysmic variable, most likely a dwarf nova of SU UMa type. Follow up observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/213809.25212824.0.png

List of Optical Transients discovered by MASTER

Global MASTER Robotic Net