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GSC 2576-02071 and GSC 2576-01248: two Algol-type eclipsing binaries studied using CCD observations and historical photographic data

An initial investigation of two poorly studied eclipsing binaries separated by ~3' in the sky is presented. The first star (GSC 2576-01248) was discovered by the TrES exoplanet search project. The second one (GSC 2576-02071) was identified by the authors during CCD observations of GSC 2576-01248. We combine our dedicated CCD photometry with the archival TrES observations and data from the digitized photographic plates of the Moscow collection to determine periods of the two variable stars with high precision. For GSC 2576-01248, addition of historical photographic data provides a major improvement in accuracy of period determination. No evidence for period change in these binary systems was found. The lightcurve of GSC 2576-01248 is characterized by a prominent variable O'Connell effect suggesting the presence of a dark starspot and asynchronous rotation of a binary component. GSC 2576-02071 shows a shift of the secondary minimum from the phase =0.5 indicating a significant orbit eccentricity.