EarthBody.cpp

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#pragma ident "$Id: EarthBody.cpp 2457 2010-08-18 14:20:12Z coandrei $"

//============================================================================
//
//  This file is part of GPSTk, the GPS Toolkit.
//
//  The GPSTk is free software; you can redistribute it and/or modify
//  it under the terms of the GNU Lesser General Public License as published
//  by the Free Software Foundation; either version 2.1 of the License, or
//  any later version.
//
//  The GPSTk is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU Lesser General Public License for more details.
//
//  You should have received a copy of the GNU Lesser General Public
//  License along with GPSTk; if not, write to the Free Software Foundation,
//  Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//
//  Wei Yan - Chinese Academy of Sciences . 2009, 2010
//
//============================================================================


#include "EarthBody.hpp"
#include "ASConstant.hpp"

namespace gpstk
{
      // Earth's rotation rate in rad/s.
   const double EarthBody::omegaEarth = 7.292115E-05;  
   
      // Equatorial radius of earth in m from WGS-84
   const double EarthBody::radiusEarth = 6378.1363e3;
   
      // Flattening factor of earth from WGS-84
   const double EarthBody::flatEarth = 0.00335281; 
   
      // Earth gravity constant in m^3/s^2 from JGM3
   const double EarthBody::gmEarth = 398600.4415e+9;    // [m^3/s^2]; JGM3

   
   
      // Returnts the dynamic Earth rotation rate. 
   double EarthBody::getSpinRate(UTCTime t)
   {
      double mjdUT1 = t.mjdUT1();
   
      double Mjd0 = floor(mjdUT1);;
      double Tu   = (Mjd0  - ASConstant::MJD_J2000)/36525.0;

      return (7292115.8553e-11 + 4.3e-15 * Tu);

   }  // End of method 'EarthBody::getSpinRate()'


}  // End of namespace 'gpstk'

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