ECLIPSE MAPPING OF STARSPOTS ON XY-UMA IN 1992 AND 1995

We present and analyse V-band light curves of the detached eclipsing b inary system XY UMa, obtained in 1992 October, 1995 March and November , and 1996 February. The light-curve morphology of this system is know n to vary on time-scales of a few days. We have used eclipse mapping t echniques to search for evidence that cool starspots are the agents re sponsible for the variability of the light curve. We derive a new set of geometric system parameters, which we find to be very similar to th ose derived by Hilditch & Bell. The image derived from the 1992 light curve shows an amorphous band of unresolved spots with a low filling f actor, extending over much of the inward-facing hemisphere of the prim ary. This result is consistent with the extent of the dark-zone model proposed by Hilditch & Bell in their earlier analysis of this same lig ht curve. Irregularities in the primary eclipse profile observed in 19 95 and early 1996 are consistent with the eclipse of a dark spot or sp ots on the inner face of the primary. The major spot in this region ap pears to be resolved on our 9 degrees surface grid, indicating that th e spot consists of an unbroken umbral region some 15 degrees in radius .