Follow-On OBS of W Ursae Majoris Stars

Recent ultraviolet observations have shown that chromospheric and transitionregion emission, which is roughly directly proportional to total radiative luminosity, is produced by practically all the W UMa binaries. This emission extends to earlier spectral type than it does for single stars. Further observations are needed to investigate the cutoff of this activity at early spectral type and to provide a better comparison between the binaries of spectral type A-F and those of type G-K. Other observations are needed to give ultraviolet (2000-3000K) light curves to be used to investigate the surface brightness distributions of both early and late-type W UMa binaries. These observations will provide the means to determine the gravity darkening and temperature difference between the components of several more systems in the way Eaton, Wu, and Rucinski did recently for W UMa with ANS data.