In the altazimuth system of coordinates, the position of a star is uniquely specified by its azimuth and either its altitude or its zenith distance. Of course the altitude and azimuth of a star are c...In the altazimuth system of coordinates, the position of a star is uniquely specified by its azimuth and either its altitude or its zenith distance. Of course the altitude and azimuth of a star are changing continuously all the time, and they are also different for all observers at different geographical locations.