The densely spotted photospheres of active type stars S.V.JEFFERS

Abstract. We have used the unique spectrophotometric capabilities of the HST to eclipse map the inner face of the F5V primary of the short period RS CVn binary SV Cam. By using STIS as a photometer, we observed three primary eclipses at intervals of 2 days, with a photometric precision of 0.0002 magnitude and cadence of 40s, over a wavelength range of 2900A ̊ to 5700Å. A preliminary analysis of the data reveals fluctuations in the lightcurve which vary from one visit to the next. These fluctuations are more pronounced at shorter wavelengths, consistent with occultations of sizeable spots and faculae on the primary