Development of Mission Catalog and Robust Identification Algorithm for Daytime Performance Extension of Star Trackers

In this article, requirement to extend star tracker performance to daytime including mission catalog and image based robust identification algorithm is considered. According to infrared point source catalogs such as 2 Micron All Sky Survey (2MASS), millions of stars are available in certain wavebands of short and near infrared. Mission catalog is filtered and uniformed version of 4000 highest quality infrared point sources2MASS. Most of 2MASS stars will be present in the star tracker field of view as spikes but not available in database. Therefore it is necessary to avoid their influence on recognition. In this algorithm, information extracted from a single pixel, whether it contains the star centroid or not is utilized. Euclidean distance transform (EDT) of every star with respect to its nearest star centroid is evaluated using Voronoi diagram of image with reduced dimension and stored in database. After processing the image, the map from each guide star is compared to database and in case the matching criterion is not satisfied, the star is eliminated in two greater loops until a similar pattern is recognizable. The algorithm shows considerable performance in the presence of spikes in the field of view.