KPL/PCK

      The SPK creations applications (mkspk, mkspk_c) require the data in
      this kernel to produce Type 10 SPK segments based upon the Two-Line
      element sets available from NORAD/SPACETRACK. The data applies ONLY
      to the Two-Line Element sets and only to the SGP4 implementations
      included in the SPICE library [1][2]. The SPK application copies 
      this data to the constants partition of the Type 10 segment, so the
      user has no need for the kernel after creation of the corresponding
      SPK.

      Bill Taber (JPL)
      Edward Wright (JPL)

      The assigned values are taken from the Spacetrack #3 report, referred
      to as WGS721 in Vallado [2]. It is possible to edit this file
      to use the high accuracy WGS-72 values (WGS72) or the WGS-84
      values (WGS84). The KE parameter value for WGS72 and WGS84
      is calculated from the MU and ER values. The lists include MU only
      for the calculation of KE.

      MU, the standard gravitational parameter, in cubic kilometer per
      second squared.

      WGS721 (STR#3 values) [1]

         ER =    6378.135

         J2   =    0.001082616
         J3   =   -0.00000253881
         J4   =   -0.00000165597

         KE   =    0.0743669161


      WGS72 [2]

         MU   =  398600.8
         ER   =  6378.135

         J2   =   0.001082616
         J3   =  -0.00000253881
         J4   =  -0.00000165597

         KE   =  60.0D0/DSQRT(ER**3/MU)
              =  0.074366916133173


      WGS84 [2]

         MU   =  398600.5
         ER   =  6378.137

         J2   =   0.00108262998905
         J3   =  -0.00000253215306
         J4   =  -0.00000161098761

         KE   =  60.0D0/DSQRT(ER**3/MU)
              =  0.074366853168714


      The BODY399_Jn values are un-normalized zonal harmonic values
      for the earth. These numbers are dimensionless.

\begindata

      BODY399_J2 =    1.082616D-3
      BODY399_J3 =   -2.53881D-6
      BODY399_J4 =   -1.65597D-6

\begintext

      The next item is the square root of GM for the earth given
      in units of earth-radii**1.5/Minute

\begindata

      BODY399_KE =    7.43669161D-2

\begintext

      The next two items define the top and bottom of the atmospheric
      drag model, distance above the surface in kilometers, used by
      the type 10 ephemeris type.

\begindata

      BODY399_QO =  120.0D0
      BODY399_SO =   78.0D0

\begintext

      The equatorial radius of the earth in kilometers as used by
      the TLE propagator.

\begindata

      BODY399_ER = 6378.135D0

\begintext

      The value of AE is the number of distance units per earth
      radii used by the NORAD state propagation software. Don't
      change this value.

\begindata

      BODY399_AE = 1.0D0

\begintext

References:

   [1] Hoots, F. R., and Roehrich, R., l. 1980. "Spacetrack Report #3, Models
       for Propagation of the NORAD Element Sets." U.S. Air Force, CO.

   [2] Vallado, David, Crawford, Paul, Hujsak, Richard,
       and Kelso, T.S. 2006. Revisiting Spacetrack Report #3. Paper
       AIAA 2006-6753 presented at the AIAA/AAS Astrodynamics
       Specialist Conference, August 21-24, 2006. Keystone, CO.