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Re: "keps" for Sun



At 08:46 AM 10/23/01 -0700, laura halliday wrote:
>No such animal, nor can there be - the Sun does not orbit
>the Earth, so satellite orbital models do not apply. The NORAD
>orbital models don't apply to the Earth/Moon system either.

Chuck and Laura are right technically, but in practice if you don't
need very high accuracy, you can use the Keplerian model to get
decent predictions for the Sun. While the Sun doesn't orbit the
Earth, the Earth does orbit the Sun, so the situation is more or
less symmetrical.

Here is a set given by P. Gerber, HB9BNI, in the documentation for his
program MoonKeps (which generates temporary pseudo-Keplerian
element sets for the Moon, and is available at
http://www.amsat.org/amsat/ftpsoft.html#pc-eme):

Sun 1995:

Epoch time: 80.092361111    year 1995
Inclination: 23.44 deg.
RAAN: 0
Arg. of perigee: 282.87 deg.
MA: 75.2803
MM: 0.0027379093

Note, however, that many tracking programs (including InstantTrack)
will reject these values as being outside the reasonable range for an
Earth satellite.

73  -Paul
kb5mu@amsat.org


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