Аннотация:Accuracy assessment of the satellite remote sensing depends on the angular attitude
estimation precision. The 1 arc second error in attitude estimation causes 2.5-meter error in the
accuracy derived from remote sensing data for the 500 km orbit.
Different kind of momentum wheels, propulsions and sensors help correct spacecraft
torque moment to stabilize it in the orbit. Star tracker is the most precise optical sensor for
spacecraft angular attitude estimation.
An onboard guide star catalog containing data for star pattern identification is essential for
star tracker operating. The total number of stars, the faintest stellar magnitude, completeness and
uniformity are the key specifications of a star catalog influencing many characteristic of a star
tracker.
The steps of creating guide star catalog are: instrumental stellar magnitude estimation with
respect to the star tracker spectral response, clusterization of nearby stars, removing of unreliable
stars and final star selection.
An iterative algorithm for thinning down the catalog allows reducing appreciably the
number of stars in the catalog and improving its uniformity. The key point of the algorithm is the
lower bound evaluation of star number in the FOV (field of view) for every boresight position
within a triangle area. The algorithm uses recursive quaternary division of the icosahedron for the
celestial sphere tessellation. The correction methods of stellar aberration and star proper motion
are discussed as well.