New CV with X-ray counterpart discovered by MASTER
ATel #6328; 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), 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), A. Parkhomenko, A. Tlatov, D. Dormidontov, V. Senik (Kislovodsk Solar Station of Pulkovo Observatory), 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 19 Jul 2014; 20:07 UT
Credential Certification: Nataly Tyurina (tiurina@sai.msu.ru)
Subjects: Optical, Cataclysmic Variable, Transient
MASTER OT J202157.69+212919.4 - new CV
MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 20h 21m 57.69s +21d 29m 19.4s on 2014-07-18.75131 UT. The OT unfiltered magnitude is 16.3m (limit 19.1m). The OT is seen in 9 images. There is no minor planet at this place. We have reference image without OT on 2011-08-25.64182 UT with unfiltered magnitude limit 18.9m.
The object at quiescence is identical to the blue star USNO-B1.0 1114-0500548 (20 21 57.693 +21 29 19.94 R1=19.62 B2=19.99 R2=19.97). Color-combined DSS finder chart is uploaded to http://master.sai.msu.ru/static/OT/J202157+212919-BRIR5x5.jpg (2x zoom). PPMXL catalog gives the proper motion of (-3.3, -6.4) mas/yr in RA and Dec. The star was in outburst on 1983-08-12 Quick-V plate and at quiescence on other 8 Palomar plates. Carlsberg Meridian Catalog 15 has r'mag=16.11, likely measured during another outburst. There is a faint X-ray source 2RXP J202157.8+212919 (0.00155 cnts/s HR1=1.00 HR2=0.49) within 2" of the OT. There is nothing at this position in GCVS and AAVSO VSX. This area of sky in Vulpecula is not covered by SDSS, GALEX, NEAT and CRTS.
Based on the blue color, ROSAT hardness ratios and previous outbursts, MASTER OT J202157.69+212919.4 is 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/202157.69212919.4.jpg
List of Optical Transients discovered by MASTER
Global MASTER Robotic Net
