Real sky performance of the prototype Orsted advanced stellar compass

The Danish microsatellite, Orsted, is equipped with an autonomous, advanced stellar compass (ASC). The ASC consists of two separate units, a Charge Coupled Device (CCD) camera head (based on a commercial Sony interline CCD detector) and a data processing unit with a powerful microcomputer (Intel 80486 type processor). The microcomputer memory contains a star catalogue which enables the microcomputer to recognize the constellations of stars in the field of view and thus derive the attitude of the ASC camera head. The mission, and the design, operation, and performance of the ASC are described. Results of ASC prototype tests at the JPL Table Mountain Observatory (TMO) facility are given.