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Subject: Bowditch Long Term Almanac Tables
From: Dan Allen (danallen46@XXX.XXX)
Date: Wed Oct 23 2002 - 12:39:58 EDT
One of the nice features of the Bowditch volumes from 1958 until 1984
is Appendix H:
Long Term Almanac
It made carrying along a Bowditch (or two from 1975 until 1984)
self-contained: it
had the theory and the tables needed to do "lifeboat" navigation. Now
of course
this useful table has been removed with no replacement in later
editions. How sad.
(These editions also had H.O. 211 as Table 35, "The Ageton Method",
also now deleted.)
The Appendix had two pages for the Sun's GHA and Dec for 10 different
dates per month,
for each month of the year. There are corrections based upon year so
that the maximum
error for altitude would not exceed 2.0' of arc. It also has
information for 38
navigational stars in a compact little table with promised errors of
less than 1.3'
of arc, as well as a table of the GHA of Aries, along with 2 auxiliary
tables. The
whole thing with explanation takes up about 5 pages. Very neat.
Question: does anyone know the source of this table? Is it just
Newcomb's formulas
put into a table? (Newcomb's formulas were the basis of the Nautical
Almanac before
computers and DE405.)
Question #2: could we come up with a newer, better, more compact long
term almanac
ourselves? Just a thought.
Dan
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