Guinan, Ambruster and s. Messina (Vill. U. & U. Catania) are
working with A. F. Lanza (Catania Obs., IT.) on a study of HD 82443 in
the Pleiades Moving Group and the results of a long-term photometric
monitoring of the young Pleiades moving group member have been submitted
to A&. A sequence of eleven optical light curves obtained from 1989
to 1995 confirms the presence of a rotational modulation with a period
of 5.40
attributable to cool photospheric spots. The Maximum
Entropy and the Tikhonov regularization criteria have been applied to
compute maps of the photospheric spot pattern. They show that the total
spotted area is subject to changes as large as 
of the star's
surface over time scales of 1-2 years, but without any indication of a
cyclical behavior. The overall spot pattern migrates at a variable rate
in the sense of the stellar rotation, suggesting the presence of a
latitudinal differential rotation with relative amplitude
. Nearly simultaneous UV
observations obtained in 1991 by Ambruster show the presence of
chromospheric and transition region plages which do not seem to be in
close spatial association with the photospheric spots. This research
was supported under grants from NSF and NASA.