Alignment of the HERA-B RICH optical system with data

We present a method for alignment of the mirror segments in the Ring Image Cherenkov Counter of the HERA-B spectrometer. The method will use recorded data, and was tested by using simulated events. The study shows that the mirrors can be aligned accurately enough to make the corresponding error in Cherenkov angle measurement negligible compared to other contributions. The mirrors are aligned relative to one mirror segment which can be chosen arbitrarily.