This data set contains the Galileo spacecraft trajectory data in three coordinate systems commonly used in the analysis of jovian magnetospheric data. These include System III (1965.0), Jupiter Solar Equatorial (JSE), and Jupiter Solar Magnetospheric (JSM) coordinates. The data are sampled every minute inside of 30 Jupiter radii, every ten minutes between 30 and 100 Rj, and every 30 minutes outside of 100 Rj. These data are all derived from the Galileo SPICE SP kernel (S980326B.XSP) which is archived with the data on volume GOMW_5001.

The Jupiter System III (1965) coordinate system follows the definition of Dr. Alex Dessler in Appendix B of 'Physics of the Jovian Magnetosphere' [DESSLER1983]. This coordinate system is the accepted standard for analysis of data from the jovian system. System III is a spherical, planetographic coordinate system where the planetary rotation rate of (9h, 55m, 29.71s) is based on the rate of rotation of Jupiter's magnetic field. The prime meridian is defined as the sub-Earth meridian at 00:00:00 UT on Jan 1, 1965. Range is measured from the Jupiter center of mass. Longitude for standard System III is measured west. This direction choice causes the coordinate system to be left-handed and to a stationary or distant observer, longitude increases with time. Left handed coordinate systems are not in common use among physicists and this definition has lead to substantial confusion over the years. Both east and west longitudes are included in this data set. Also included is the local time of the spacecraft where noon is defined to be the sub-Sun direction, midnight in the anti-Sun direction, etc.

The Jupiter Solar Equatorial (JSE) coordinate system is a Cartesian coordinate system defined by using the Sun direction and the Jupiter spin axis and equator. Distances are measured from the Jupiter center of mass and are provided here in units of jovian radii (1 Rj = 71492 km). Z-axis is taken along the Jupiter spin axis, positive in the northern hemisphere (OMEGA). The X-Z plane contains the instantaneous vector to the Sun center of mass (SUN), as observed by Jupiter. Thus:

   JSE_Z = OMEGA                                                              
   JSE_Y = OMEGA x SUN                                                        
   JSE_X = JSE_Y x JSE_Z                                                      

The Jupiter Solar Magnetospheric (JSM) coordinate system is a Cartesian coordinate system defined by using the Sun direction and the Jupiter dipole moment vector as principal vectors. The dipole selected is the best fit, centered dipole, defined to be tilted 9.6 degrees towards 202 degrees System III (1965.0) west longitude [CONNERNEY1981] in the northern hemisphere. The positive X direction is taken to be the instantaneous direction to the Sun center of mass, as observed by the Jupiter center of mass. The XZ-plane is defined to contain the magnetic dipole vector (M). Thus M x X = Y and X x Y = Z. Distances are measured from the Jupiter center of mass and are provided here in units of jovian radii.

The JSM coordinate system is primarily used in the analysis of data from regions where both the solar wind flow velocity (-X) and the rotating Jovian magnetic field are important but where the solar wind flow is still the dominant force (near the magnetopause and in the magnetosheath).

Data are stored in a single ASCII file (POS_DATA.TAB). 
File structure is described by the detached PDS label files: 
    POS_DATA.LBL  (Describes file parameters)


Columns in all data files:
=====================================================
name      type       description
-----------------------------------------------------
time      char       Sample time in PDS time format number    
R         float      Range from Jupiter in Rj where 1 Rj) = 71492 km.
S3_LAT    float      Joviagraphic latitude of the S/C in degrees.
S3_WLON   float      System III west longitude of the S/C in degrees
JSE_X     float      X Jupiter Solar Equatorial (JSE) coordinates (Rj)
JSE_Y     float      Y Jupiter Solar Equatorial (JSE) coordinates (Rj)
JSE_Z     float      Z Jupiter Solar Equatorial (JSE) coordinates (Rj)
JSM_X     float      X Jupiter Solar Magnetospheric (JSM) coordinates (Rj)
JSM_Y     float      Y Jupiter Solar Magnetospheric (JSM) coordinates (Rj)
JSM_Z     float      Z Jupiter Solar Magnetospheric (JSM) coordinates (Rj)
local_hr  float      Local time  (decimal hours)
mag_hr    float      Magnetic local time  (decimal hours)   


Any data column whose value is 999.999 is a missing data value.


Useful Documents:

   Mission description

   Spacecraft description

   Data set description