Acquisition and track algorithms for the Astros star tracker

The Astros star tracker has been designed for an employment with the Space Shuttle. An achievement of the performance levels needed has required critical trade-offs between the hardware design and the control algorithms. This paper provides a description of the development of the acquisition and track algorithms. Attention is given to an Astros system overview, a system firmware description, cluster evaluation, guide star selection, exposure time determination, video data input, update interval timing, exposure time sequencing full frame video A/D conversion, analog threshold for acquisition, minimum threshold determination, and the theoretical basis for the track algorithm.