Celestial Navigation

The observations involve two measurements: the angle of the body above the horizon, and the exact time that angle is measured. At least two sets of measurements are needed, either from two different celestial objects, or for the same celestial object at two different times (at least a few minutes apart).

Mathematics is used to find one's position on the surface of the Earth from the measurements. Centuries of tradition and refinements by such men as Nathaniel Bowditch have reduced the mathematical part to a series of lookups in printed tables of numerical data, which a navigator can use without understanding the mathematical details.

However, the underlying geometrical concepts can easily be translated into algebra, which in turn can be written into simple programs on virtually any computer system or programmable calculator. Approaching the subject in this way will result in a much deeper understanding of it, as well as a much easier method of application, once the computer programs are functioning.

Various pages of this site will present:

• Pub. 229 calculator
• Calculate fix from 2 GPs & Heights
• The geometrical relation between the sky and the Earth,
• The representation of this geometry via vectors and their algebra,
• Translating the algebra into various computer versions (HP41C, C on a PC),
• The construction, function, and use of the sextant,
• The measurements made by a celestial navigator,
• The astronomical data in the Nautical Almanac.

For comments and questions please send e-mail to blubwat@optonline.net