1998A&A...331..612M

Optical observations of the galactic supersoft X-ray source RX J0019.8+2156 reveal essential changes of the lightcurve from night to night. From October to December 1996 time resolved UBVRI photometry was performed with the high speed multichannel multicolour photometer MCCP at the 80cm telescope of the Wendelstein Observatory of the Universitaets-Sternwarte Muenchen. To model these observations we compute lightcurves using a code which includes as sources of radiation the irradiated disk with an elevated outer rim and the irradiated secondary star in a consistent way. As found earlier the accretion disk rim is an important feature. We show in our investigation, that the variability of the optical flux can be understood as resulting from changes of the rim height, either from night to night or even within hours.