The transmitted data consists of Solar limb data from the SAS, CCD pixels around the intersection of a Solar image with three linear CCDs, and Star event data from the RAS, CCD pixels induced by passages of Star images over a linear CCD. Fig. 2 shows the flow diagram of the aspect solution software. The Solar limbs and the Star events are fitted independently. Knowing the geometry of all features of the SAS, the position of the Sun center, with respect to a spacecraft fixed coordinate system, can be calculated, and a list of position angle marks can be generated by fitting of the Star events and subsequent comparison with a Star catalog. Integrating these information allows a correction and interpolation of the roll angles. Finally, the coordinates are converted into the needed pointing and roll angle format with respect to a Solar fixed coordinate system.