ROTSE1 J164341.65+251748.1: a new W UMa-type eclipsing binary

ROTSE1 J164341.65+251748.1 was photometrically observed in the V band during three epochs with the 0.84-m telescope of the San Pedro Mártir Observatory in Mexico. Based on additional BVR photometry, we found that the primary star has a spectral type around G0V. The light curve of the system is typical of a W UMa type binary stars and has an orbital period of ≈ 0.323 days. In an effort to gain a better understanding of the binary system and determine its physical properties, we analyzed the light curve with the Wilson and Devinney method. We found that ROTSE1 J164341.65+251748.1 has a mass ratio of ≈ 0.34 and that the less massive component is about 230 K hotter than the primary star. The inclination of the system is ≈ 84.6 degrees, and the degree of over-contact is 11%. The analysis shows the presence of variable bright spots on the primary star.