Astronomical Applications Department, U.S. Naval Observatory novas c 2 doc Page 40
40
4.18.1.2
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 solarsystem
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:
7
×
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. This 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.
