SOLARSYSTEM, Version 3
RETURNED
VALUE:
(short int)
0...Everything OK.
1...Input Julian date ('tjd') out of range.
2...Invalid value of 'body'.
Discussion:
This version of solarsystem provides the position and velocity of the Earth or Sun without reference to
any external data file. The heliocentric position and velocity of the Earth are computed by evaluating
trigonometric series. When barycentric positions and velocities are required, a number of somewhat crude
approximations are involved; therefore, barycentric positions and velocities computed by this version of
SOLSYS are less accurate than heliocentric positions and velocities. The resulting errors should be less
than the following values:
Maximum error in heliocentric positions:
6
×
10
-6
AU
Maximum error in heliocentric velocities:
8
×
10
-7
AU/day
Maximum error in barycentric positions:
8
×
10
-4
AU
Maximum error in barycentric velocities:
2
×
10
-6
AU/day
When this version of solarsystem is used in the computation of the apparent place of the Sun, it should
contribute less than 2 arcseconds error. When this version of solarsystem is used in the computation of
apparent places of stars, it should contribute less than 2 milliarcseconds error.
The above error assessment applies to the interval 18002050.
Note: This version of solarsystem calls several other functions in the NOVAS-C package.
The body identification numbers to be used with this version are: Sun,
body
=0,
body
=1, or
body
=10; Earth,
body
=2 or
body
=3.
