Mapping system for star sensors with two focal lengths

The star sensor (1) comprises an optical imaging system (2) with a lens (4) imaging a predetermined field of view (17,19) around an optical axis (7) on a sensor surface (6) of a detector (5) along an optical path (10,11). The lens has two partial lenses (8,9) with different focal lengths imaging simultaneously on the sensor surface with light patterns (15,22) separated partially from each other by a computing unit (3). An independent claim is included for a method for operating a star sensor.