This data sets consist of Voyager 1 & 2 Jupiter encounter ephemeris data in Heliographic coordinates. Two versions, both covering the same time period, but containing slightly different data, are provided. One version was generated by the Voyager MAG team from Voyager 1 SEDR, the other by the PDS/PPI node using the VG1_JUP.BSP and PCK00003.TPC SPICE kernels. Two versions of the spacecraft ephemeris data are provided as an attempt to correct some of the problems in the Voyager SEDR while preserving the ability to reproduce early results. The original SEDR data has a variety of problems which may affect the knowledge of the spacecraft position, or conversely, the timing associated with certain events such as ring plane crossings. The SPICE SPK kernels provided in the data set include corrections to some, but not all, of the problems associated with the Voyager SEDR. The Navigation and Ancillary Information Facility (NAIF) at JPL may issue a new Voyager SPK kernel in the future that will further improve the knowledge of the spacecraft location in inertial space.
There are other differences in the two versions of ephemeris data that are the result of improvements in the knowledge of some of the physical constants associated with Jupiter and its moons. Since the Voyager era, there have been updates to the orientation of the jovian spin axis right ascension and declination, the radius of Jupiter, as well as the orbital characteristic and other physical parameters of many of the moons of Jupiter. These changes affect the stated position of the spacecraft in jovigraphic coordinate systems like System III without changing the position of the spacecraft in inertial space. The spin rate of Jupiter is not changed from the System III (1965) rate of 9h 55m 29.71sec (870.536 deg/day). The SPICE planetary constants kernel (PCK) contains both the current IAU definitions of the physical constants for the bodies within in the jovian system (as data) as well as the older IAU definitions (as comments).
These data are housed in the PDS/PPI node (See below)
VG1 at Jupiter: VG1-J-POS-6-SUMM-HGCOORDS-V1.0
1979-02-26 to 1979-03-24.
VG1 at Jupiter: VG1-J-POS-6-SUMM-S3COORDS-V1.1
1979-03-03 to 1979-03-16.
VG2 at Jupiter: VG2-J-POS-6-SUMM-HGCOORDS-V1.0
1979-06-20 to 1979-08-18.
VG2 at Jupiter: VG2-J-POS-6-SUMM-S3COORDS-V1.1
1979-07-05 to 1979-08-12.
- A listing of team members to facilitate literature searches.