Author(s): P. K. Seidelmann, P. M. Janiczek and R. F. Haupt
Published in: NAVIGATION, Journal of the Institute of Navigation, Volume 23, Number 4
Pages: 303 - 312
Cite this article: Seidelmann, P. K., Janiczek, P. M., Haupt, R. F., "THE ALMANACS- YESTERDAY, TODAY AND TOMORROW", NAVIGATION, Journal of The Institute of Navigation, Vol. 23, No. 4, Winter 1976-1977, pp. 303-312.
Full Paper: ION Members/Non-Members: 1 Download Credit
Sign In
Abstract: During the last two centuries an evolution has taken place in the almanacs available to navigators and it appears that it will continue into the future. While almanacs have been available for at least two thousand years, the first official almanac, Connaissante des Temps, was issued in 1679, the British Nautical Almanac was first published in 1767, and the American Ephemeris and Nautical Almanac first appeared for 1856. The British and Americans have combined their separate publications into the Nautical Almanac and the Air Almanac. The contents of the almanacs have changed over the years from publications of lunar distances and the use of astronomical days to publishing the data in Greenwich hour angles and the use of Universal Time. The publication methods have progressed from hand set type for a letter press, to intermediate methods involving offset printing where the camera copy has been prepared on a tabulator and a card- operated typewriter. During the last decade electronic printing methods have been used where the flow of information at electronic speeds is automatic from the basic data to the printed page. The near future, with hand-held calculators, digital sextants wired to specialized computers, and shipboard computers promises even greater changes. The almanac for the computer might contain algorithms for calculating such items as stellar positions, refraction corrections and solutions of the navigational triangle and Chebyshev series for calculating the hour angles of the Sun, Moon and planets. A realistic evaluation of the capabilities that the new computers and calculators can provide for celestial navigation indicates that the navigator will require, in addition to the present almanacs, data specially prepared for his calculator, machine readable tapes or cards containing the almanac, or algorithms which he can include in his computer programs.