Before revision: In a terrestrial spherical model, the equation of isoazimuth line of initial course C passing through point S(B, L) is: Isoazimutal of a star In this case the X point is the illuminating pole of the observed star, and the angle Z is its azimuth.
After revision: In a terrestrial spherical model, the equation of isoazimuth curve with initial course C passing through point S(B, L) is: Isoazimutal of a star In this case the X point is the illuminating pole of the observed star, and the angle Z is its azimuth.