ksasteroid.cpp

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/***************************************************************************
                          ksasteroid.cpp  -  K Desktop Planetarium
                             -------------------
    begin                : Wed 19 Feb 2003
    copyright            : (C) 2001 by Jason Harris
    email                : jharris@30doradus.org
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/

#include "ksasteroid.h"

#include <kdebug.h>

#include "dms.h"
#include "ksnumbers.h"
#include "kstarsdata.h"

KSAsteroid::KSAsteroid( int _catN, const QString &s, const QString &imfile,
                        long double _JD, double _a, double _e, dms _i, dms _w, dms _Node, dms _M, double _H, double _G )
        : KSPlanetBase(s, imfile),
          catN(_catN), JD(_JD), a(_a), e(_e), i(_i), w(_w), M(_M), N(_Node), H(_H), G(_G)
{
    setType( SkyObject::ASTEROID );
    //Compute the orbital Period from Kepler's 3rd law:
    P = 365.2568984 * pow(a, 1.5); //period in days
}

KSAsteroid* KSAsteroid::clone() const
{
    return new KSAsteroid(*this);
}

bool KSAsteroid::findGeocentricPosition( const KSNumbers *num, const KSPlanetBase *Earth ) {
    //determine the mean anomaly for the desired date.  This is the mean anomaly for the
    //ephemeis epoch, plus the number of days between the desired date and ephemeris epoch,
    //times the asteroid's mean daily motion (360/P):
    dms m = dms( double( M.Degrees() + ( num->julianDay() - JD ) * 360.0/P ) ).reduce();
    double sinm, cosm;
    m.SinCos( sinm, cosm );

    //compute eccentric anomaly:
    double E = m.Degrees() + e*180.0/dms::PI * sinm * ( 1.0 + e*cosm );

    if ( e > 0.05 ) { //need more accurate approximation, iterate...
        double E0;
        int iter(0);
        do {
            E0 = E;
            iter++;
            E = E0 - ( E0 - e*180.0/dms::PI *sin( E0*dms::DegToRad ) - m.Degrees() )/(1 - e*cos( E0*dms::DegToRad ) );
        } while ( fabs( E - E0 ) > 0.001 && iter < 1000 );
    }

    double sinE, cosE;
    dms E1( E );
    E1.SinCos( sinE, cosE );

    double xv = a * ( cosE - e );
    double yv = a * sqrt( 1.0 - e*e ) * sinE;

    //v is the true anomaly; r is the distance from the Sun
    double v = atan2( yv, xv ) / dms::DegToRad;
    double r = sqrt( xv*xv + yv*yv );

    //vw is the sum of the true anomaly and the argument of perihelion
    dms vw( v + w.Degrees() );
    double sinN, cosN, sinvw, cosvw, sini, cosi;

    N.SinCos( sinN, cosN );
    vw.SinCos( sinvw, cosvw );
    i.SinCos( sini, cosi );

    //xh, yh, zh are the heliocentric cartesian coords with the ecliptic plane congruent with zh=0.
    double xh = r * ( cosN * cosvw - sinN * sinvw * cosi );
    double yh = r * ( sinN * cosvw + cosN * sinvw * cosi );
    double zh = r * ( sinvw * sini );

    //the spherical ecliptic coordinates:
    double ELongRad = atan2( yh, xh );
    double ELatRad = atan2( zh, r );

    helEcPos.longitude.setRadians( ELongRad );
    helEcPos.latitude.setRadians( ELatRad );
    setRsun( r );

    if ( Earth ) {
        //xe, ye, ze are the Earth's heliocentric cartesian coords
        double cosBe, sinBe, cosLe, sinLe;
        Earth->ecLong().SinCos( sinLe, cosLe );
        Earth->ecLat().SinCos( sinBe, cosBe );

        double xe = Earth->rsun() * cosBe * cosLe;
        double ye = Earth->rsun() * cosBe * sinLe;
        double ze = Earth->rsun() * sinBe;

        //convert to geocentric ecliptic coordinates by subtracting Earth's coords:
        xh -= xe;
        yh -= ye;
        zh -= ze;
    }

    //the spherical geocentricecliptic coordinates:
    ELongRad = atan2( yh, xh );
    double rr = sqrt( xh*xh + yh*yh + zh*zh );
    ELatRad = atan2( zh, rr );

    ep.longitude.setRadians( ELongRad );
    ep.latitude.setRadians( ELatRad );
    if ( Earth ) setRearth( Earth );

    EclipticToEquatorial( num->obliquity() );
    nutate( num );
    aberrate( num );

    return true;
}

void KSAsteroid::findMagnitude(const KSNumbers*)
{
    double param     = 5 * log10(rsun() * rearth() );
    double phase_rad = phase().radians();
    double phi1      = exp( -3.33 * pow( tan( phase_rad / 2 ), 0.63 ) );
    double phi2      = exp( -1.87 * pow( tan( phase_rad / 2 ), 1.22 ) );
    
    setMag( H + param - 2.5 * log( (1 - G) * phi1 + G * phi2 ) );
}

void KSAsteroid::setPerihelion( double perihelion )
{
    q = perihelion;
}

void KSAsteroid::setEarthMOID( double earth_moid )
{
    EarthMOID = earth_moid;
}

void KSAsteroid::setAlbedo( float albedo )
{
    Albedo = albedo;
}

void KSAsteroid::setDiameter( float diam )
{
    Diameter = diam;
}

void KSAsteroid::setDimensions( QString dim )
{
    Dimensions = dim;
}

void KSAsteroid::setNEO( bool neo )
{
    NEO = neo;
}

void KSAsteroid::setOrbitClass( QString orbit_class )
{
    OrbitClass = orbit_class;
}

void KSAsteroid::setOrbitID( QString orbit_id )
{
    OrbitID = orbit_id;
}

void KSAsteroid::setPeriod( float per )
{
    Period = per;
}

void KSAsteroid::setRotationPeriod(float rot_per)
{
    RotationPeriod = rot_per;
}

//Unused virtual function from KSPlanetBase
bool KSAsteroid::loadData() { return false; }

SkyObject::UID KSAsteroid::getUID() const
{
    return solarsysUID(UID_SOL_ASTEROID) | catN;
}