Astral, or Celestial Navigation : finding your way, or your position on the planet, by observation of heavenly bodies; that is, the stars, the sun, the planets, or the moon, (not Elle McPherson), using as tools the sextant, chronometer, and sight reduction tables.
The Science of astral navigation as described above is now virtually obsolete, since satellite navigation using pre-programmed computing devices has superseded the sextant. When, as occasionally happens, electronic navigation and communication devices are rendered inoperative by adverse conditions at sea (i.e. they get wet), the study of sight reduction may be a life-saving exercise. The Student will find suitable information to research this subject, however, there have never been available the absolutely necessary logical worksheets on which to enter information and calculation. Old admiralty forms provide no guidance, though since publication (25 years ago now) others have been devised, but none so concise and inclusive of all possible data. Careful reading of the two worksheets will reveal how every contingency is allowed for, step by step. The Sight-reduction Worksheets and Instructions (© 1988) reproduced below have proved to be invaluable tool at sea, and in combination with initial study of the science. The Worksheets were originally printed in blocks of 50 and sold for a nominal price. The first sheet contains introductory instructions for use, each other leaf has the worksheet on the recto, and noon sight form on the verso, bound A5 and perforated for a standard folder. The Reader is welcome to reproduce these forms free of any charge or caveat, with my best wishes. But think of the labour that went into designing them!
