Peremennye Zvezdy (Variable Stars) 26, No. 7, 2006
Received 14 June; accepted 20 October.
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|We present the discovery and the times of primary minima for the eclipsing binary TYC 1744 2329 1 = ASAS 003933+2730.5. Our CCD observations compared to times of minima derived from the archival photographic plates and from the NSVS and ASAS-3 data clearly show that the orbital period of the system is variable.|
The eclipsing binary TYC 1744 2329 1 = USNO-A2.0 1125-00240848 =
ASAS 003933+2730.5 ( = 0393303, = +273029 3 (J2000.0)) was discovered by one of the authors (K. Sokolovsky) on the plates of Moscow collection taken with the 40-cm astrograph in Crimea. The star was estimated by eye on 112 plates for the interval JD2436077-2447835. The phased light curve for the light elements
Our first CCD photometry session was carried out in 2004 July at the 50-cm Maksutov telescope of the Crimean Laboratory (Sternberg Astronomical Institute) equipped with a Pictor 416XTE CCD camera with a Johnson filter. The images were dark subtracted, flat-fielded and analyzed with the aperture photometry software developed by V.P. Goranskij, and (Sokolovsky & Lebedev, 2005). Unfortunately, both night-time minima during our observation set could be observed only partially (Fig.3). We combined the two incomplete light curves taken on July 17 and 30 to determine a single epoch of the primary minimum.
In 2005 July, we could not observe this star in Crimea because of bad weather, so in 2005 October, we carried out one more set of observations of the variable with the instruments of the Ka-Dar Public Observatory located in the Moscow Region. The light minima were observed on October 10 (the MEADE LX200GPS Schmidt-Cassegrain Telescope and SBIG STL-6303 CCD camera with an IR-cut filter) and on October 31 (simultaneously at the MEADE LX200GPS Schmidt-Cassegrain Telescope equipped with an unfilterred SBIG ST-2000XM CCD camera and at the Vixen (D = 103 mm) refractor with an unfiltered SBIG STL-6303 CCD). The corresponding light curves are shown in Fig.4.
Table 1. Times of primary minima and residuals.
|HJD 24...||Error, d||, d||, d||Source|
The times of minima derived from all available observations are
listed in Table1. The times of minima that were obtained not
from continuous observations but are individual faint points on
the phased light curve (as in the cases of photographic or ASAS-3
observations) should be considered to have an uncertainty slightly
larger than half-duration of the total eclipse (2.4 hours). The
residuals in the Table were calculated for the average light
elements (linear elements for all available observations, which
are not good because of the period changes):
The phased light curves for the NSVS and ASAS-3 observations plotted using the current light elements are given in Fig.5.
Finally, note that the minima observed on October 9, 2005 and in July, 2004 show weak trends (decreases of brightness) during the total eclipse, while the data taken at the two Ka-Dar telescopes simultaneously on October 31, 2005 show the total eclipse to be nearly flat.
Fig. 2. The diagram for the average linear light elements. The photographic light elements and the current ones are shown as dashed and solid lines respectively. The times of the faintest light (shown as open circles) were adopted as the times of primary minima for photographic and ASAS-3 observations.
Fig. 3. The two partially observed minima. Crimea, the 50-cm Maksutov telescope with a Pictor 416XTE CCD camera.
Fig. 4. The two primary minima observed in 2005 at the telescopes of the Ka-Dar observatory, Moscow region. (a) October 10, the MEADE LX200GPS SCT and a SBIG STL-6303 CCD camera. (b) October 31, the MEADE LX200GPS SCT with a SBIG ST-2000XM CCD camera. (c) October 31, the Vixen (D = 103 mm) refractor with a SBIG STL-6303 CCD camera.
Acknowledgements: Two of the authors (K. Sokolovsky and S. Antipin) are grateful to the Russian Foundation of Basic Research (grants No. 05-02-16289 and 05-02-16688) for partial support of this study.
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