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"Peremennye Zvezdy", Prilozhenie, vol. 6, N 1 (2006)

USNO-B1.0 1323-0548678: a New EW Star in the Field of BL Lac

K. V. Sokolovsky, V. R. Amirkhanyan
Sternberg Astronomical Institute, Moscow, Russia

ISSN 2221–0474

Received:   23.01.2006;   accepted:   27.01.2006
(E-mail for contact: idkfa@sai.msu.ru)

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Star Name: USNO-B1.0 1323-0548678, USNO-A2.0 1275-16931746 Coordinates (J2000): 22 02 27.75, +42 18 02.8 Variability type: EW;   Limits, System: 15.8 - 16.0 (V);     Period: 0.3546 d;   Epoch(min): JD 2451069.6369

Remarks:

A series of BVR (Johnson - Cousins) images of the field of BL Lacertae was taken in 1998-2000 using the Zeiss-600 telescope of the Special Astrophysical Observatory (Russian Academy of Sciences) and the automated photometer TAZIK-1 with a liquid-nitrogen-cooled CCD (Amirkhanyan et al., 2000). The data reductions are described in Amirkhanyan (2006). The data set was examined using the Welch - Stetson method (Welch, Stetson, 1993) implemented in the VAST software (Sokolovsky, Lebedev, 2005), resulting in the discovery of a previously unknown variable star. The star can be classified as an EW eclipsing variable with a 0.3546-day period. The variability amplitude is about 0.3 magnitude (R). The observed colours are B-V=0.89+/-0.05; V-R=0.51+/-0.04. According to the NED data base, the Galactic extinction (in the version according to Schlegel et al., 1998) in the direction of BL Lac is 1.420(B), 1.091(V), and 0.880(R) magnitudes, meaning that the intrinsic colours can be as blue as B-V=0.56, V-R=0.30. There is no evidence for a change in colour during eclipse. The BVR magnitudes were calibrated using standards listed by Gonzalez-Perez et al. (2001). Acknowledgments: We would like to thank S.V. Antipin for useful discussion of the results and V.P. Goransky for providing software used for our light-curve analysis. This study made use of the SIMBAD database which is operated at CDS, Strasbourg, France and the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory of Technology under contract with the National Aeronautics and Space Administration.

References:

Amirkhanyan, V.R., 2006, Astronomy Reports, in press Amirkhanyan, V.R., Vikul'ev, N.A., Vlasyuk, V.V. et al., 2000, Bull. Special Astrophys. Obs., 50, 142 Gonzalez-Perez, J.N., Kidger, M.R., Martin-Luis, F., 2001, Astron. J., 122, 2055 Schlegel, D.J., Finkbeiner, D.P., Davis, M., 1998, Astrophys. J., 500, 525 Sokolovsky, K., Lebedev, A., 2005, in 12th Young Scientists' Conference on Astronomy and Space Physics, Kyiv, Ukraine, April 19-23, 2005, eds.: Simon, A.; Golovin, A., p.79 (VAST: http://saistud.sai.msu.ru/poisk) Welch, D., Stetson, P., 1993, Astron. J., 105, 1813