Data Set Overview
    =================
      This data set contains Ulysses ephemeris data near Jupiter
      covering the dates 1992-01-25 to 1992-02-18. Two slightly
      different versions of these data are included. The first
      (TRJ25_48.TAB), provided by the Ulysses MAG team (Imperial
      College/JPL), includes position data in Sys 3 spherical, ECL50
      spherical, and ECL50 Cartesian coordinates. The Ulysses spin
      axis position is also provided in ECL50 spherical coordinates.
      The second version (SPK25_48.TAB), generated at the PDS/PPI
      node (UCLA), includes Sys 3 spherical trajectory, plus a
      spacecraft local time. Note that the position values for these
      two versions differ slightly. This variation is due to
      differences in the definitions of the Jovian physical
      constants used to generate them.
 
 
    Data
    ====
 
    TRJ25_48.TAB
    ------------
      The file TRJ25_48.TAB contains positions and attitude of
      Ulysses. Time resolution is the same as the final SEDR: 3
      hours for Days 25-31, 1 minute for Days 32-47, 1 hour for Day
      48.
 
      This file simply contains convenient extractions of parameters
      from the Final SEDR. These were reformatted at the PDS/PPI
      node to provide time tags consistent with those used on the
      rest of the ULYSSES JUPITER ENCOUNTER CD-ROM, and merged from
      multiple data files into a single encounter file.
 
      TRJ25_48.TAB is an ASCII (CR/LF) format file consisting of the
      following columns:
 
      column   type     description
 
      time     a24      time in the format yyyy-mm-ddThh:mm:ss.sssZ
      R        f10.5    distance from Jupiter to Ulysses (RJ; 1 RJ =
                        71398 km)
      RLATJG   f8.3     spacecraft jovian (Sys 3) latitude (degrees)
      RLONJG   f8.3     spacecraft west (Sys 3) longitude (degrees)
      RLATEC   f8.3     latitude of the Jupiter-to-Ulysses unit
                        vector in ECL50 (degrees)
      RLONEC   f8.3     longitude of the Jupiter-to-Ulysses unit
                        vector in ECL50 (degrees)
      AXISLAT  f8.3     latitude of Ulysses spin axis in ECL50
                        (degrees)
      AXISLON  f8.3     longitude of Ulysses spin axis in ECL50
                        coordinates (degrees)
      XSU      1pe15.8  Cartesian X of Sun-to-Ulysses vector in
                        ECL50 (km)
      YSU      1pe15.8  Cartesian Y of Sun-to-Ulysses vector in
                        ECL50 (km)
      ZSU      1pe15.8  Cartesian Y of Sun-to-Ulysses vector in
                        ECL50 (km)
 
      This file may be read according to the fortran format
      statement: '(a24,1x,f10.5,6(1x,f8.3),3(1x,1pe15.8))'.
 
 
    SPK25_48.TAB
    ------------
      This file contains positions in Sys 3 coordinates,
      plus a local time to provide a sun reference. Positions are
      provided in 60 second samples for the entire interval. Times
      coincide with those for the 60 second averaged magnetometer
      data provided to the PDS/PPI node by the Ulysses MAG team.
 
      These data were generated from Ulysses SPICE at the PDS/PPI
      node (UCLA). SPICE uses the latest IAU conventions as the
      Jovian physical constants. The values used in this case
      were those cited in the 1991 IAU report. The value used for
      1 RJ = 71492 km.
 
      SPK25_48.TAB is an ASCII (CR/LF) format file consisting of the
      following columns:
 
      column   type     description
 
      time     a24      time in the format yyyy-mm-ddThh:mm:ss.sssZ
      R        f10.5    Jupiter to spacecraft range (jovian radii)
      LAT      f8.3     spacecraft Jovian (Sys 3) latitude
                        (degrees)
      LON      f8.3     spacecraft Jovian west longitude (degrees)
      LocTime  f8.3     angular separation between the meridian
                        containing the sun and the one containing
                        the spacecraft converted to a time. The sun
                        meridian is defined to be noon (12.000), with
                        midnight (0.000) opposite it. Dawn (6.000)
                        and dusk (18.000) are where the sun rises and
                        sets according to the planet's rotation
 
      This file may be read according to the fortran format
      statement: '(a24,1x,f10.5,3(1x,f8.3))'.
 
 
    Coordinate System
    =================
      System III (1965.0) (Sys 3) is a jovicentric left handed
      coordinate system defined such that longitude increases with
      time as viewed by a stationary remote observer.
 
      Jovicentric System III (1965.0) spherical coordinates
 
      R      Jupiter to spacecraft range (positive away from
             Jupiter)
 
      LAT    completes the left handed, orthogonal set
 
      LON    System III (1965) west longitude (with longitude
             increasing westward from a specific jovian prime
             meridian)
 
 
    Coordinate Transformation Matrices
    ----------------------------------
      The file TRJ25_48.TAB contains all the parameters necessary to
      transform the field components into System III, ECL50, or
      inertial spacecraft coordinates. The paragraphs below give
      methods for computing transformation matrices using these
      parameters. As an alternative, note that the appendix in
      [SMITH&WENZEL1993] contains the orbital elements of Ulysses
      with respect to Jupiter and demonstrates how to calculate the
      position of Ulysses in System III and other coordinate systems
      without recourse to trajectory data files.
 
      The transformation matrix from R-THETA-PHI to System III
      (1965.0) consists of the column vectors of the R, THETA, and
      PHI axes expressed in System III. The R-axis in System III is
      cos(RLATJG) cos(360-RLONJG), cos(RLATJG) sin(360-RLONJG),
      sin(RLATJG). The PHI axis is the normalized crossproduct J x
      R, where J is the rotation axis which is just 0,0,1, so the
      unit vector in the PHI direction is -sin(360-RLONJG),
      cos(360-RLONJG), 0. The unit vector in the THETA direction is
      the crossproduct PHI x R = sin(RLATJG) cos(360-RLONJG),
      sin(RLATJG) sin(360-RLONJG), -cos(RLATJG).
 
      The transformation matrix from R-THETA-PHI back to ECL50
      consists of the column vectors of the R, THETA, and PHI axes
      expressed in ECL50. R is cos(RLATEC) cos(RLONEC), cos(RLATEC)
      sin(RLONEC), sin(RLATEC). PHI is the normalized crossproduct
      J x R, where J (North Pole of Jupiter) is given in the
      reference [SMITH&WENZEL1993] as -92.002 RA, 64.504 DEC,
      Earth Mean Equinox and Equator 1950.0. Rotating by 23.4458
      deg (1950.0 obliquity) gives J in ECL50 = (-.015037545, -
      .035534090, 0.999255323). The THETA axis is PHI x R.
 
      Inertial spacecraft coordinates are defined as follows: Z is
      the Ulysses spin axis, which points approximately towards
      Earth; X is is perpendicular to Z and lies in the plane
      containing Z and S, where S is the Ulysses-to-Sun vector. X is
      positive toward the Sun. Z in ECL50 is cos(AXISLAT)
      cos(AXISLON), cos(AXISLAT) sin(AXISLON), sin(AXISLAT). S in
      ECL50 is -XSU, -YSU, -ZSU. The Y axis is the normalized
      crossproduct Z x S, and the X axis is Y x Z. The
      transformation matrix from ECL50 back to inertial spacecraft
      coordinates consists of the column vectors X, Y, and Z.
 
      The EPHEM files in this submission include all the parameters
      necessary to calculate the above transformations. In a few
      cases where the direction of the spin axis was not available
      in the SEDR, the Ulysses-to-Earth direction was substituted in
      the EPHEM files. It is suggested that interpolations in time
      be performed on vector components rather than angles in order
      to avoid difficulties near 0 or 360, and that double precision
      arithmetic be used in matrix multiplication.