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 find 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 \sim 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 \sim 0.34 and that the less massive component is over 230 K hotter than the primary star .
The inclination of the system is \sim 84.6 degrees , and the degree of over-contact is 11 % .
The analysis shows the presence of variable bright spots on the primary star .