We caught IP Peg in four nights on decline from an outburst. The introduction of a disk rim in our reconstruction method allowed us to apply the eclipse mapping method without light curve decomposition or spline correction. The results show a disk with regions having a flat brightness temperature profile. Simulations show that an assumed hole in the disk is not able to explain this flat profile. Also a high disk rim, shading the inner regions, is not likely. A possible explanation could be an optically thick and geometrically flat wind-layer on the disk's surface, correlated with the hot part of the disk and decreasing in radius during the decline from outburst. During decline from outburst the part of the disk which is assumed to be the cooling front, travelled inward about 0.35 in three days, which gives a travelling speed of about 800 m/s. The brightness temperature during the decline from outburst varied between about 8000 Kelvin in the "hot" and about 4500 Kelvin in the "cold" regions of the disk.
© European Southern Observatory (ESO) 1997
Online publication: April 6, 1998