SATELLITE NAVIGATION BY TERRESTRIAL OCCULTATIONS OF STARS I: GENERAL CONSIDERATIONS NEGLECTING ATMOSPHERIC REFRACTION AND EXTINCTION

The condition for terrestrial occultation of a star as seen from a satellite is derived in terms of the orbital elements of the satellite and the equatorial coordinates of the star. An occultation equation relating the time of occultation to the orbital elements is also derived. Relevant stellar properties are discussed. The frequency of occultations as a function of perigee distance and eccentricity of the orbit is obtained. A general discussion of the minimum number of stars required for satellite navigation, and the corresponding limiting magnitude of the satellite-borne telescope is given. Except for references to other reports of this series where atmospheric effects are considered, all results are derived on the assumption that the earth is a perfect sphere and has no atmosphere.