Some navigation and almanac algorithms

Abstract

This report presents a detailed discussion of the use of the general spherical triangle as a means of eliminating the many special cases of quadrant determination that plague most navigation computations and steal memory from computer programs. Also included are two programs, NAVALGOR and NAVEPHM which are written for the Radio Shack TRS-80 Model 4 Computer. NAVALGOR implements three sets of computational procedures: direct solution algorithms for speroid and spherical earth models, inverse solution algorithms for spheroid and spherical earth models, and rhumb line approximations to great circle routes. NAVEPHM implements a procedure for the determination of the position of the Sun, Moon and navigational planets that reproduce 'The Nautical Almanac' and 'The Air Almanac' to within 0.2'. Keywords include: Navigation, Air Almanac, Ephemeris, Spheroid Earth, Spherical Triangle, Almanac, Nautical Almanac, Great Circle, Rhumb Line, and General Spherical Triangle