PDS_VERSION_ID                    = PDS3
RECORD_TYPE = STREAM
OBJECT = TEXT
NOTE = "Notes on using pointing geometry software."
PUBLICATION_DATE = 2012-024
END_OBJECT = TEXT
END
The geometry values included in the data object labels are computed using 
the software contained in the GEOMETRY_ENGINE.PRO file located under the
SOFTWARE/GEOM directory and using the NAIF SPICE software library. The latter
is freely available for most platforms and operating systems (FTP site: 
naif.jpl.nasa.gov pub/naif/toolkit directory). In order to perform these
calculations, the SPICE software requires kernel files including a spacecraft
clock coefficients file (.tsc), a leap seconds file (.tls), a Cassini p
constants file (.tpc), a Cassini Spacecraft Frame Definitions Kernel (.tf), a
UVIS Instrument Kernel (ti), and all sp kernels relevant to the time of the
observations.  Kernels can also be obtained from the NAIF FTP site.          
Users seeking geometry information do not need to use these programs; users 
should refer to the PDS labels.  All geometry values in the label are computed
at the time given by the START_TIME keyword value.  Geometry values in the
labels include:

RIGHT_ASCENSION: 
  right ascension of the instrument axis on the celestial sphere.  Computed
  using CSPICE_PXFORM and CSPICE_RECRAD
DECLINATION: 
  declination of the instrument axis on the celestial sphere.  Computed
  using CSPICE_PXFORM and CSPICE_RECRAD
SUB_SOLAR_LATITUDE:
  latitude of sub-solar point (using nearpoint method) (deg).
  Computed using CSPICE_SUBSOL and CSPICE_RECLAT
SUB_SOLAR_LONGITUDE:
  latitude of sub-solar point (using nearpoint method) (deg).
  Computed using CSPICE_SUBSOL and CSPICE_RECLAT
SUB_SPACECRAFT_LATITUDE:
  latitude of sub-spacecraft point (using nearpoint method) (deg).
  Computed using CSPICE_SUBPT and CSPICE_RECLAT
SUB_SPACECRAFT_LON:
  longitude of sub-spacecraft point (using nearpoint method) (deg).
  Computed using CSPICE_SUBPT and CSPICE_RECLAT
PHASE_ANGLE:
  phase angle on the specified target at the specified time at the the point
  intersected by the instrument boresight (deg).  Computed using CSPICE_ILLUM.
EMISSION_ANGLE:
  emission angle on the specified target at the specified time at the point
  intersected by the instrument boresight (deg).  Computed using CSPICE_ILLUM.
SOLAR_INCIDENCE_ANGLE:
  solar incidence angle, measured from the local target surface. Computed
  using CSPICE_ILLUM.
CENTRAL_BODY_DISTANCE:
  distance above target surface (km). Computed using CSPICE_SUBPT.
SC_PLANET_POSITION_VECTOR:
  low order 3-elements of the  state of the spacecraft with respect to planet.
  If the target is a satellite, this value is with respect to the planet that
  the satellite orbits.  Computed using CSPICE_SPKEZR.
SC_PLANET_VELOCITY_VECTOR:
  high order 3-elements of the  state of the spacecraft with respect to
  planet.  If the target is a satellite, this value is with respect to the
  planet that the satellite orbits.  Computed using CSPICE_SPKEZR.
SC_TARGET_POSITION_VECTOR:
  3-element vector with position of S/C wrt to target (km) in inertial frame.
  Computed using CSPICE_SPKEZR.
SC_TARGET_VELOCITY_VECTOR:
  3-element vector with velocity of S/C wrt to target (km/sec) in inertial
  frame.  Computed using CSPICE_SPKEZR.
SC_SUN_POSITION_VECTOR:
  3-element position of Sun with respect to the target body. 
  Computed using CSPICE_SPKEZR.
SC_SUN_VELOCITY_VECTOR:
  3-element vector with velocity of S/C wrt to target (km/sec) in inertial
  frame.  Computed using CSPICE_SPKEZR.
PLANET_CENTER_POSITION_VECTOR:
  3-element position of planet with respect to the solar system barycenter.
  Computed using CSPICE_SPKSSB
PLANET_CENTER_VELOCITY_VECTOR:
  3-element velocity vector of planet with respect to the solar system
  barycenter.  Computed using CSPICE_SPKSSB