Photospheric spots and a chromospheric place on V523 Cassiopeiae

The cool, overcontact, close binary, V523 Cassiopeiae was observed with the 1 m reflector at the US Naval Observatory, Flagstaff Station. The photomet ry was very good, with a precision on the order of a few millimagnitudes, b ut not numerous enough for complete light-curve analyses (e.g., differentia l corrections). A conventional published synthesis has been found acceptabl e as a fiducial model, and most of the observational weight has been used t o develop a spot model for the stars and to support the validity of theoret ical limb-darkening coefficients. Both photospheres and chromospheres contr ibute to the model. This result indicates that multifilter measures of this and similarly cool binaries are necessary for fuller descriptions of stell ar activity cycles. A number of newly determined times of minimum light sol idify the published rate of period variability.