Long Term Almanac 2000 - 2050

As electronic systems become the principal means of navigation, celestial navigation is being relegated to a backup role. However, the usefulness (if not the necessity) of a celestial navigation backup capability makes attractive an almanac which is easily stowed and does not need annual replacement, thus avoiding the danger of it being out of date when needed.

The main body of the Almanac consists of Ephemerides from which the Greenwich Hour Angle (GHA) of the sun, the declination of the sun and the GHA of Aries may be determined for any time from the year 2000 to 2050.

These are based on the fact that approximately correct values for the position of the sun and the GHA of Aries may be obtained from any almanac that is exactly four years out of date. By applying quadrennial correction factors, an ephemeris for any given year may be used to determine the position of the sun and GHA of Aries to good accuracy, exactly four years hence and multiples thereof.

The period of validity of these tables has been set at 50 years, that being the period for which simple, linear, quadrennial correction factors will still give good accuracy (about 0.3') for corrected table values.

Tables for the positions of 39 selected navigational stars, including Polaris, are given for the year 2000. Annual correction factors are also given to account for their subsequent apparent motion, so that their positions may be calculated for any subsequent year.

Star charts showing the positions of the selected stars are also given. These stars are also shown in the context of prominent constellations and other stars.

As well as the usual tables for refraction and dip, concise tables for sight reduction are given. These tables may be used to compute a calculated altitude and azimuth from an estimated position. These tables should determine the altitude within one minute.

To order your book

You can order your book online using any popular credit card. The sale of the book will be handled by the "CCNow" e-commerce company. The sales price are given in US dollars. Just click on the price appropriate to the place where you live.

For those living in the UK, the price including Post and Packing is $23

For those living in Europe, the price including Post and Packing is $24

For those living anywhere else in the world, the price including Post and Packing is $29

Sight Reduction Tables worksheet

A worksheet for the concise sight reduction tables used in the Almanac is now available. It will fit on one side of A4 paper, but it is in A5 format. If a number of sheets are printed on both sides, they can be folded and stapled together to form an A5 sized booklet.

If your paper format is 8.5"x 11", then it may be necessary to scale down the worksheet to fit the paper. This is easily done when you print out the worksheet using Adobe Acrobat.

Travels in the Sahara Desert - An Exercise in Celestial Navigation

The author recently participated in an expedition to the Southern Sahara desert. He visited the Libyan Desert Glass area, saw rock engravings in Wadi Abd el Melik (the site of the fabled lost city of Zerzura) and saw cave paintings in the Gilf Kebir. He also visited the site of a crater newly discovered from examining satellite images of the Sahara. See an account of this trip in which the Long Term Almanac 2000 - 2050 was used to stay found in the desert.