Celestial Navigation Net - ZetaTalk

Navigator Light Software
Artificial Horizon
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If you live in a city far from the sea, you can't take altitudes of celestial bodies with a marine sextant, because
you can't see the sea horizon. One way to work around this problem is to use an artificial horizon. The artificial
horizon can easily be made with a plate filled with liquid. Water will do, but oil is better. The surface of a pool can
also be used, if there is no wind or waves (the water surface must be completely flat).
To take the altitude with the artificial horizon, point the sextant towards
the artificial horizon and make reflected image of the celestial body
coincide with the direct image. The angle you read is twice the altitude of
the body, as illustrated in the figure below.
Also read the index error.
Navigator automatically corrects for the use of artificial horizons:
● The program divides instrumental altitude by two. Enter sextant reading directly.
● The Dip and semi-diameter corrections are set to zero.
● The index error is also divided by two.
Printing Nautical Almanac Pages
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Navigator (registered version 2.5 or latter) has a Nautical Almanac page generator/printer. These pages are not
exactly the same as real almanac pages, but they contain most of the information needed to do celestial
calculations in the traditional way, without the computer.
Navigator generates the so-called "daily pages" (the ones with 3-day celestial data for planets, stars, Sun, Aries
and Moon). The yellow ("increments") pages are not generated because they don't change from year to year.
You can use the yellow pages of an old almanac or do the interpolations with a pocket calculator.
I choose to make the Navigator daily pages as similar as possible to actual almanac pages. But there are
differences:
● Did not include the latitude dependent tables (Twilights, Sunrise, Moonrise, Sunset, Moonset).
● Did not include the Aries meridian passage time. This number is used to calculate the meridian passage of
stars, and is seldom used.
● Did not include the Sun's Equation of Time and meridian passage table. You may use an old almanac for
the Sun's meridian passage calculations, as these tables are almost unchanged from year to year. Just
use the table of the same day.
● Did not include the Moon's meridian passage and age table.
● Did not include the planets' SHA and meridian passage table.
● Added three stars not included in most Nautical Almanacs
I plan to include some of these numbers in future versions. Feedback from users about what features are most
important is welcome.
If you compare the Navigator's almanac pages with nautical almanac pages, you will note small differences in the
http://www.tecepe.com.br/nav/navpro.htm (12 of 28) [9/6/2004 1:15:33 PM]