Fourier analysis of the light curves of W UMa-type stars

The light curves of 30 well observed W UMa-type systems are analysed according to Kopal's method for the study of the light changes of eclipsing variables by using frequency-domain techniques. New geometric and photometric elements are derived and new values for the gravity-darkening coefficients are also given. Finally, an answer to the problem of whether or not these are contact systems is attempted. (Auth.)