The long-term X-ray lightcurve of RX J0527.8--6954
  Supersoft X-ray sources are commonly believed to be stably burning white dwarfs. However, the observations of some supersoft sources show dramatic variability of their X-ray flux on timescales ranging from days to years. Here, we present further observational data of the supersoft X-ray source RX J0527.8--6954 exhibiting a continuous decline over the past 5 yrs. With no clear trend of a concordant temperature decrease this might suggest a evolutionary scenario where the WD leaves the steady burning branch and the combined effect of reduced luminosity and cooling at constant radius produces the observed effect. 
J. Greiner, R. Schwarz, G. Hasinger, M. Orio