The art of celestial navigation, centuries old, continues to be exciting in the era of electronic navigation. Making physical measurements and evaluating calculated results is intellectually stimulating and satisfying. Electronic systems, with their ease of use, have made navigation accessible even to those deterred by long mathematical processes. Computers (PCs) are among these devices. The PC (or a handheld calculator) replaces bookkeeping tedium. Results are the same but with speed and accuracy. Regardless, we need to remain faithful to the basic skills and keep our almanacs and sight reduction tables handy.
This CELESTIAL series of programs are designed to fulfill the celestial navigation requirements of both a short cruise or an ocean crossing. No attempt is made to add piloting, dead reckoning [DR] methods, great circle courses, bearing evaluation, etc. to avoid cluttering a pure celestial series. These topics are interesting but are part of the basic skills of a navigator who has progressed beyond the beginner mysteries of piloting, vectors, and DR.
These are four (4) different programs which accomplish separate tasks in a user-friendly manner. The user is led through each program by a simple question-and-answer format requiring yes/no answers and decisions on navigation and data inputs. These answers are those normally required to complete any celestial problem.
Accuracy produced by these programs is to small-boat accuracy requirements. This means that you will not be dealing in yards, as some programs claim (or remain silent), but in miles or parts of miles. While based on astronomical methods, astronomers would not use these types of calculations except for very casual observations. Accuracy is bounded by the method used to calculate sidereal time, sidereal hour angle [SHA], and Declination. Once these values are obtained, the accuracies of celestial navigation computations become a matter of decimal places.
Conservatively, these programs should be valid and give excellent results for about 100 years from 1992. Beyond that, the simple methods for computing star precession and planetary orbit element constants will begin to affect the results. Whether or not this is significant for a small boat navigator may be debatable.
These programs are not tutorial.
Click on these links:
Email me if you have questions at agrupp@earthlink.net.
George Rupp