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A New Low-Mass Eclipsing Binary from SDSS-II

We present observations of a new low-mass double-lined eclipsing binary system discovered using repeat observations of the celestial equator from the Sloan Digital Sky Survey II. Using near-infrared photometry and optical spectroscopy we have measured the properties of this short-period [P=0.407037(14) d] system and its two components. We find the following parameters for the two components: M_1=0.272+/-0.020 M_sun, R_1=0.268+/-0.010 R_sun, M_2=0.240+/-0.022 M_sun, R_2=0.248+/-0.0090 R_sun, T_1=3320+/-130 K, T_2=3300+/-130 K. The masses and radii of the two components of this system agree well with theoretical expectations based on models of low-mass stars, within the admittedly large errors. Future synoptic surveys like Pan-STARRS and LSST will produce a wealth of information about low-mass eclipsing systems and should make it possible, with an increased reliance on follow-up observations, to detect many systems with low-mass and sub-stellar companions. With the large numbers of objects for which these surveys will produce high-quality photometry, we suggest that it becomes possible to identify such systems even with sparse time sampling and a relatively small number of individual observations.