THE CONTACT BINARY-SYSTEM YY ERI

Relatively new and unanalysed photometric data-sets of the contact bin ary system YY Eri are presented. The light curves have been analysed u sing information limit optimization techniques, and the 'Binary Maker' program of Bradstreet (1992). Comparison of the results allows insigh t into determinacy questions affecting the 'W UMa type' of light curve , which relates to our general understanding of contact binaries. A li miting contact configuration cannot be ruled out on the basis of empir ical data-analysis alone. Very careful analysis of the photospheric fl ux distribution over the surface of the Sun may help establish appropr iate values of the gravity brightening parameter for cool dwarf stars. At present, however, empirical photometric information on contact bin aries is non-discriminatory: i.e. alternative cosmogonies can find alt ernative support from available evidence. The implication is then for more and better observational data to allow better real independent pa rameter determination.