Art Carlson wrote:
> That's exactly what I had in mind. This is a rule that can be easily
> understood and remembered, as opposed to remember to ADD nine hours to the
> clock time for a three-quarter moon, if it is WANING. What I would like to
> figure out is the errors involved in both methods, given orbital parameters.
[...]
> --Art Carlson
Here are some rough parameters. The maximum deviation of the ecliptic
from the equator is 23.5 degrees. In other words the maximum
deviation of the point where the ecliptic meets the horizon from the
true east or west compass point is 23.5 degrees. That's where my
remarks about knowing the time of year and time of day comes in--it
gives the information about this deviation. If you have a celestial
planisphere, it probably has markings for the ecliptic and celestial
latitude. Give it a good examination to get a feel for how the
deviations behave over the course of a year and day.
However, the moon does not lie precisely along the ecliptic, but can
deviate from it by a maximum of about 5 degrees (I'm not certain of
that max. deviation, and I don't have my books with me). Plus, there
will be error in tracing out the ecliptic through the sky as I first
suggested.
In sum, the procedure I gave is pretty rough.
Jim
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| Jim Cobb | 540 Arapeen Dr. #100 | [EMAIL PROTECTED] |
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Through infinite mist, software reverberates
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