Celestial navigation with the stereographic projection

Abstract

The major exercise in celestial navigation requires the calculation of the observer's latitude and longitude given a standard time, the data, some celestial data (almanac) and some celestial observations, usually the sextant heights of two celestial objects. Although this method successfully solves the problem, in practice it is more normal first of all to assume one's dead reckoning position, then for a given time precalculate the heights of two stars. Both of the major steps in these methods involve the use of the astronomical spherical triangle and many students stumble at this step and lose sight of the processes involved. The use of the stereographic projection allows the concepts to remain clear and the calculations and measurements to be completed rapidly, which more than compensates in the learning situation for the limitation in accuracy to +or-0.5.