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Light curves of the contact systems visible in the direction of Baade'sWindow have been analyzed using the first coefficients of the Fourierrepresentation. The results confirm that the geometric contact betweencomponents is usually weak. Systems showing significant differences in thedepths of eclipses are very rare in the volume-limited sample to 3 kpc: only 2among 98 contact systems show the difference larger than 0.065 mag; for mostsystems the difference is <0.04 mag. If this relative frequency of 1/50 isrepresentative, then one among 12,500 - 15,000 Main Sequence F-K spectral-typestars is either a semi-detached or poor-thermal-contact system. Below theorbital period of 0.37 day, no systems with appreciable differences in theeclipse depths have been discovered. Since large depth differences are expectedto be associated with the "broken-contact" phase of the Thermal RelaxationOscillations, this phase must be very short for orbital periods above 0.37 dayand possibly entirely absent for shorter periods. In the full sample, which isdominated by intrinsically bright, distant, long-period systems, largereclipse-depth differences are more common with about 9% of binaries showingthis effect. Sizes of these differences correlate with the sense of light-curveasymmetries (differing heights of maxima) for systems with orbital periodslonger than 0.4 day suggesting an admixture of semi-detached systems withaccretion hot spots on cooler components. The light-curve amplitudes in thefull sample as well as in its volume-limited sub-sample are surprisingly smalland strongly suggest a mass-ratio distribution steeply rising toward moredissimilar components. Many low mass-ratio systems remain to be discovered inthe sky field.Comment: latex 14 pages of text and 14 figures (aastex40 and psfig), submitted  to AJ; the first paper astro-ph/9607009 will appear in AJ, Jan.199

Eclipsing Binaries in the OGLE Variable Star Catalog.II.Light Curves of the W UMA-Type Systems in Baade's Window