<h2>Rosetta Ephemeris</h2>
 
<UL>

    Rosetta Ephemeris data are calculated using SPICE kernels taken from the
           <a href="ftp://ssols01.esac.esa.int/pub/data/SPICE/ROSETTA/kernels/" TARGET=_BLANK>
            PSA</a><br/><br/>   
   <UL> <b>Coordinates :</b> <br/><br/>  
   <li><b>GSE</b> : Geocentric Solar Ecliptic -
         This system has its X axis towards the Sun and its Z axis
         perpendicular to the plane of the Earth's orbit around the
         Sun (positive North). Y completes the right-handed system.
   <li> <b>GSM</b> : Geocentric Solar Magnetospheric -
         This system has its X axis towards the Sun and its Z axis
         is the projection of the Earth's magnetic dipole axis
         (positive North) on to the plane perpendicular to the X
         axis. Y completes the right-handed system.
    
    <li> <b>MSO</b> : Mars-centric Solar Orbital   -  
        the +X-axis points toward the Sun, 
        +Z points northward perpendicular to Mars's orbit plane, and 
        Y completes the right hand system nominally directed opposite Mars's orbital velocity around the Sun.
        
    <li><b>HCI</b>: Heliocentric Inertial Frame -
         All vectors are geometric: no aberration corrections are used.
         The solar rotation axis is the primary vector: the Z axis points
         in the solar north direction.
         The solar ascending node on the ecliptic of J2000 forms the X axis.
         The Y axis is Z cross X, completing the right-handed reference frame.
    <li><b>HEE</b> : Heliocentric Earth Ecliptic Frame -

         All vectors are geometric: no aberration corrections are used.

         The position of the Earth relative to the Sun is the primary vector:
         the X axis points from the Sun to the Earth.

         The northern surface normal to the mean ecliptic of date is the
         secondary vector: the Z axis is the component of this vector
         orthogonal to the X axis.

         The Y axis is Z cross X, completing the right-handed reference frame.
    <li><b>HEEQ</b> : Heliocentric Earth Equatorial Frame -

         All vectors are geometric: no aberration corrections are used.

         The solar rotation axis is the primary vector: the Z axis points
         in the solar north direction.

         The position of the Sun relative to the Earth is the secondary
         vector: the X axis is the component of this position vector
         orthogonal to the Z axis.

         The Y axis is Z cross X, completing the right-handed reference frame.
     
   
  <li><b>CSO</b> The body-Centered Solar Orbital frames for the Rosetta primary
   target comet 67P/Churyumov-Gerasimenko, incidental target comet
   45P/Honda-Mrkos-Pajdusakowa (Rosetta passed through its ion tail in
   July 2006), and secondary targets asteroids 2867/STEINS and
   21/LUTETIA are named '67P/C-G_CSO', '45P/H-M-P_CSO',
   '2867/STEINS_CSO', and '21/LUTETIA_CSO'. 
   These frames are defined as
   a two-vector style dynamic frames as follows:
 
      -  The position of the sun relative to the body is the primary
         vector: the X axis points from the body to the sun.

      -  The inertially referenced velocity of the sun relative to the
         body is the secondary vector: the Y axis is the component of
         this velocity vector orthogonal to the X axis.

      -  The Z axis is X cross Y, completing the right-handed reference
         frame.

      -  All vectors are geometric: no aberration corrections are used.
 
    

   <li><b>CSEQ</b>  The body-Centered Solar EQuatorial frames for the Rosetta
   primary target comet 67P/Churyumov-Gerasimenko and secondary target
   asteroid 21/LUTETIA are named '67P/C-G_CSEQ' and '21/LUTETIA_CSEQ'.
   These frames are defined as a two-vector style dynamic frames as
   follows:
 
      -  +X axis is the position of the Sun relative to the body; it's
         the primary vector and points from the body to the Sun;

      -  +Z axis is the component of the Sun's north pole of date
         orthogonal to the +X axis;

      -  +Y axis completes the right-handed reference frame;

      -  the origin of this frame is the body's center of mass.

   All the vectors are geometric: no aberration corrections are used.
  </UL>
<br/>