<h2>GIOTTO Ephemeris: P1/Halley FlyBy</h2>
 
<UL>
    GIOTTO Ephemeris data are calculated using SPICE kernels taken from the
           <a href="http://naif.jpl.nasa.gov/pub/naif/GIOTTO/kernels/" TARGET=_BLANK>
            NAIF</a><br/><br/>   
   <UL> <b>Coordinates :</b> <br/><br/>  
   <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 GIOTTO
   target comet P1/Halley, is named 'P1/H_CSO' 
   This frame is   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.
 
  </UL>
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