Data Set Overview
      =================
      This data set consists of Voyager 2 Jupiter encounter
      ephemeris data in Heliographic coordinates covering the period
      1979-06-20 to 1979-08-18. 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 2 SEDR, the other by the PDS/PPI node using the
      VG2_JUP.BSP and PCK00003.TPC SPICE kernels.

      Due to inaccuracies in Voyager SEDR, as well as changes in the
      values of some key parameters (e.g. Jovian radius) the timing
      is improved for the SPICE generated data. However, since much
      of the original analysis was based upon the SEDR generated
      ephemeris, this data has been included as well.

      SEDR generated ephemeris
      ------------------------
      Data Supplier         : NSSDC
      Data sampling rate    : 96 seconds
      Data Set Start Time   : 1979-06-20T00:00:00.334Z
      Data Set Stop Time    : 1979-08-18T23:59:08.143Z

      SPICE generated ephemeris
      -------------------------
      Data Supplier         : S. Joy
      Data sampling rate    : 48 seconds
      Data Set Start Time   : 1979-06-20T00:00:00.334Z
      Data Set Stop Time    : 1979-08-18T23:59:56.143Z

      Parameters
      ==========

      SEDR generated ephemeris
      ------------------------

      PARAMETER  RESOLUTION/  DESCRIPTION
      NAME       UNITS

      time       96.0 Sec.    time of the sample (UT) in the format
                              yyyy-mm-ddThh:mm:ss.sssZ

      m65536     counts       spacecraft clock counts
      mod60
      fds_line

      sc_x       AU           heliographic cartesian coordinates
      sc_y                    position vectors: X, Y, and Z
      sc_z

      vel_x      km/s         heliocentric X, Y, and Z spacecraft
      vel_y                   velocity components
      vel_z

      sc_r       AU           heliographic spherical coordinates
      sc_lat     degrees      position vectors: range, latitude, and
      sc_lon     degrees      longitude

      SolEquatorial_to_HG     solar equatorial to heliographic
                              coordinates rotation matrix containing
                              9 1pe15.8 elements

      HG_to_EarthOrbTrue      heliographic to earth orbit true
                              coordinates rotation matrix containing
                              9 1pe15.8 elements

      Spacecraft_to_HG        payload (spacecraft) to heliographic
                              coordinates rotation matrix containing
                              9 1pe15.8 elements

      SPICE generated ephemeris
      -------------------------
      PARAMETER  RESOLUTION/  DESCRIPTION
      NAME       UNITS

      time       48.0 Sec     time of the sample (UT) in the
                              format yyyy-mm-ddThh:mm:ss.sssZ

      R          AU           heliographic spherical coordinates
      LAT        degrees      position vectors: range, latitude, and
      LON        degrees      and longitude


      Coordinate System
      =================
      The Heliographic coordinate system is a heliocentric system
      defined in the reference epoch of 1950. The unit vectors which
      define the coordinate system are as follows:

      Heliographic cartesian coordinates

      X                points towards the the first point of Aries
                       in the solar equatorial plane on the vernal
                       equinox of the reference epoch 1950 (positive
                       away from the Sun)

      Y                completes the right handed set (X x Z)

      Z                points along the Sun's spin axis (positive
                       above the equatorial plane)

      Heliographic spherical coordinates

      R (Range)        the distance from the Sun's position at the
                       reference epoch to the spacecraft in AU

      LAT (Latitude)   the angle between the solar equatorial plane
                       of the reference epoch measured in the plane
                       containing the solar spin axis of that epoch
                       (positive above the equatorial plane)

      LON (Longitude)  longitude is zero in the direction of the
                       ascending node at the reference epoch (X
                       direction) and increasing in the direction of
                       planetary orbital motion (note that LON does
                       not rotate with the Sun)

      For the SPICE data, the definition used for astronomical units
      is 1 AU = 149674000 km. The longitude of the ascending node
      was calculated using the equation:

        LON = 74 [degrees] 22' + 0.84' * ( year - 1900 ).

      The inclination of the Sun's North pole measured relative to
      the ecliptic was defined as being 7 [degrees] 15' in 1950.

      Data Coverage
      =============
Filename         Records             Start                 Stop
-------------------------------------------------------------------
Volume ID: VG_1502
 SEDR_HG_96S.TAB 45925  1979-06-20T00:00:00.334Z  1979-08-18T23:59:08.143Z
SPICE_HG_48S.TAB 91855  1979-06-20T00:00:00.334Z  1979-08-18T23:59:56.143Z

Confidence Level Overview
      =========================

      SPICE generated ephemeris
      -------------------------
      The SPICE generated data were derived from SPICE using software
      that has been extensively tested. They should give as accurate
      representation of spacecraft ephemeris as possible using these
      kernels.

      Missing Data Flag
      =================
      Any SEDR generated ephemeris data column whose value is
      -9.99999999e+10 is a missing data value.