Astronomical Applications Department, U.S. Naval Observatory - novas c 2 doc (Page 37)

37

4.18.1.1

SOLARSYSTEM, Version 2

RETURNED

VALUE:
(short int)
0...Everything OK.
1...Invalid value of body or origin.
2...Error detected by JPL software.

Discussion:

This version serves as the interface between the Jet Propulsion Laboratory's lunar and

planetary ephemeris software and NOVAS-C. The function contains a single call to
Fortran subroutine jplint, which in turn calls pleph and other Fortran subroutines in the
JPL ephemeris software package. The user is responsible for obtaining the Fortran
ephemeris code and data, setting up the binary, random-access ephemeris file, and linking
the JPL Fortran code with NOVAS-C. See the Implementation Notes below.

The body identification numbers to be used with this version are: Sun,

body

= 10;

Mercury,

body

= 1; Venus,

body

= 2; Earth,

body

= 3; Mars,

body

= 4; Jupiter,

body

= 5; Saturn,

body

= 6; Uranus,

body

= 7; Neptune,

body

= 8; Pluto,

body

= 9;

Moon,

body

= 11.

Implementation Notes:

In order to use NOVAS-C with solarsystem version 2, you must first obtain the

export planetary ephemeris package from JPL. Be sure to choose an ephemeris whose
coordinates are oriented to the mean equator and equinox of standard epoch J2000.0,
such as DE200, DE405, or DE406. The export package is available over the Internet
from the anonymous ftp server navigator.jpl.nasa.gov/ephem/export and consists of
several large ASCII data files and software provided in the form of Fortran source code.
An installation guide is also included. Alternatively, the export package is also available
on CD-ROM from Willmann-Bell, Inc. (www.willbell.com) for a modest fee. The
installation process consists of converting (large) files of ASCII ephemeris data to binary,
direct-access form using a supplied utility program. Then, the binary file is verified using
another utility program and a file of comparison data. If the verification process is
successful, the ephemeris file is ready to use. The ephemeris data is obtained from the
binary file by calling the access subroutines provided in the export package.

Important Note

Over the years, there have been several versions of the JPL export ephemeris software.
The following discussion specifically refers to the software version available on the "JPL
Planetary and Lunar Ephemerides" CD-ROM ©1997.

Version 2 of solarsystem (C code) obtains ephemeris data from the binary file by

calling Fortran subroutine jplint, which is part of the NOVAS-C package. Subroutine