New light curve analysis and period changes of the overcontact binary EQ Tauri

• We carried out new observations of the eclipsing binary EQ Tauri and plotted light curves in BVR filters.
• We obtained times of light minimum and determined new ephemeris for primary minimum of EQ Tau.
• We calculated and plotted O–C diagram of EQ Tau and calculated the period changes.
• We analyzed the BVR light curves and determined some geometrical and physical parameters.

A photometric CCD study of EQ Tauris was carried out in the R, V and B bands. These new data were analyzed by using the PHOEBE and Binary Marker 3 programs, which yielded the geometrical system parameters and mass and radius of both stars. We find these to confirm the results of Pribulla and Vanko (2002). Using these new data together with data from the literature, the orbital period variations were studied by using the Kalimeris method. We find the same timescale of variability of the orbital period as Pribulla and Vanko (2002), namely about 49 years.