| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 882.1 | | CTCADM::ROTH | If you plant ice you'll harvest wind | Fri Jun 03 1988 16:07 | 13 |
| Look in the Nautical Almanac; the expression is actually very
complex, involving an expansion in Chebyshev polynomials.
It results from a hairy perturbation analysis of the orbits
of the planets, etc.
There is a version of the Almanac that does have the series
expansions - it's the one commonly used by astronomers.
For a sundial, you don't really need the accuracy though. It may
be simpler to look in one of the Dover paperbacks that explains
the theory of sundials.
- Jim
|
| 882.2 | | CTCADM::ROTH | If you plant ice you'll harvest wind | Fri Jun 03 1988 16:08 | 4 |
| One other note - the Almanac is available in diskette form nowadays.
That may be more useful than the paper copy...
- Jim
|
| 882.3 | Keep horology nuclear free, bring back sundials. | BIOMIC::TURRELL | I will not Reason and Compare: | Mon Jun 06 1988 16:05 | 8 |
| Jim,
Thanks for the reference, I'll see if I can dig it out. I take your
point re the accuracy but you know how these things can get under the
skin when you get going. Also I rather liked the idea of coding a
short simulation program.
Pete_T.
|
| 882.4 | From the Mills Book... | SDOGUS::DRAKE | Dave (Diskcrash) Drake 619-292-1818 | Mon Jun 13 1988 05:37 | 25 |
| There is a good reference to be found in,
"Positional Astronomy and Astro-Navigation Made Easy"
H.R. Mills Halsted Press, John Wiley and Sons of New York
ISBN 0-470-99324-3
From page 218
assume w=(360 * number of days from January 1st / 365.25)
assume RA= sun's right assention on the given date
The approximate Equation of Time
E= -7.64 sin (w) + 9.863 sin (2 * RA)
another approximation
L= sun's longitude from Norton's Star Atlas or similar
E = -7.64 sin (L +78) + 9.863 sin (2 * L)
page 220 discusses analemmatic noon marks for sundial fabrication.
Hope this helps.
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