are used to determine spacecraft orientation. A typical star catalogue for high-fidelity attitude determination is originated from a standard base catalog (for example from the United States Naval Observatory) and then filtered to remove problematic stars, for example due to apparent magnitude variability, color index uncertainty, or a location within the Hertzsprung-Russell diagram implying unreliability. These types of star catalogs can have thousands of stars stored in memory on board the spacecraft, or else processed using tools at the ground station and then uploaded. See also Celestial navigation GoTo (telescopes) Sun sensor References Spacecraft attitude control Astrodynamics Orbits Spaceflight concepts Celestial navigation Navigational equipment