On Wed, 04 May 2005 16:01:07 GMT, Dennis Lee Bieber <[EMAIL PROTECTED]> wrote:
>On Tue, 03 May 2005 16:28:34 GMT, Dennis Lee Bieber
><[EMAIL PROTECTED]> declaimed the following in comp.lang.python:
>
>
>> It's not going to be easy, though... <G>
>
> Yes, talking to myself... I crawled through one of my texts (at
>work) yesterday. This is incomplete -- I wasn't going to copy the entire
>chapter -- but may serve as an example of some of the complexity that
>goes into some of the entries found in almanacs:
>
>From: "Spherical Astronomy" [Robin M. Green; 1985 Cambridge University]
>
>"The 1980 theory of nutation contains 106 terms both in longitude and
>the obliquity"
>
>Displacement of true celestial pole from mean pole, /principal/ terms
>only -- lunar caused nutation
>
>Nutation in longitude = -17".1996 sin omega
> -1".3187 sin (2F - 2D + 2 omega)
> -0".2274 sin (2F - 2 omega)
>Nutation in obliquity = 9".2025 cos omega
> + 0".5736 cos (2F - 2D + 2 omega)
> + 0".0927 cos (2F - 2 omega)
>
>Where:
> omega = mean longitude of the node (I presume of the moon)
> F = mean argument from node (moon)
> D = mean elongation from sun (moon)
>
>Periods of interest:
>18.6 year lunar (movement of the node),
>6 month solar,
>14 day lunar...
>
>26000 year luni-solar precession
>
I wonder why the original post, which I presume was
http://mail.python.org/pipermail/python-list/2005-April/278752.html
doesn't show up in google groups, but can seemingly only be found indirectly
by google search on "smoothing algorithms" site:python.org giving one main post
http://mail.python.org/pipermail/python-list/2005-April/278871.html
which is a reply with no immediate apparent parent. And then going to the
sorted-by-thread index, where you can find the original.
Maybe it's because there was an html attachment (which I didn't "wget" to
investigate)?
Anyway, the original post sounds like the OP was really just looking for better
numbers
than in some text tables he found, and not really for a way of estimating
better numbers based
on flawed data (though that was what he apparently thought his best option was,
using the
rounded text tables as data). I'd bet that is not his best option, especially
since distributions
of actual roundoff errors can be weird. There must be tons of
telescope-pointing and planetarium-driving
software out there that can do similar stuff. And if that's not accurate
enough, the relevant
newsgroup crowd will be able to advise, I'd bet.
Regards,
Bengt Richter
--
http://mail.python.org/mailman/listinfo/python-list
