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Diffstat (limited to 'kstars/kstars/ksasteroid.cpp')
| -rw-r--r-- | kstars/kstars/ksasteroid.cpp | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/kstars/kstars/ksasteroid.cpp b/kstars/kstars/ksasteroid.cpp new file mode 100644 index 00000000..4ac314fb --- /dev/null +++ b/kstars/kstars/ksasteroid.cpp @@ -0,0 +1,135 @@ +/*************************************************************************** + 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 <kdebug.h> + +#include "ksasteroid.h" +#include "dms.h" +#include "ksnumbers.h" +#include "ksutils.h" +#include "kstarsdata.h" + +KSAsteroid::KSAsteroid( KStarsData *_kd, QString s, QString imfile, + long double _JD, double _a, double _e, dms _i, dms _w, dms _Node, dms _M, double _H ) + : KSPlanetBase(_kd, s, imfile), kd(_kd), JD(_JD), a(_a), e(_e), H(_H), i(_i), w(_w), M(_M), N(_Node) { + + setType( 10 ); //Asteroid + setMag( H ); + //Compute the orbital Period from Kepler's 3rd law: + P = 365.2568984 * pow(a, 1.5); //period in days +} + +bool KSAsteroid::findGeocentricPosition( const KSNumbers *num, const KSPlanetBase *Earth ) { + //Precess the longitude of the Ascending Node to the desired epoch: + dms n = dms( double( N.Degrees() - 3.82394E-5 * ( num->julianDay() - J2000 )) ).reduce(); + + //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 = atan( yv/xv ) / dms::DegToRad; + //resolve atan ambiguity + if ( xv < 0.0 ) v += 180.0; + + 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 = atan( yh/xh ); + //resolve atan ambiguity + if ( xh < 0.0 ) ELongRad += dms::PI; + double ELatRad = atan( zh/r ); //(r can't possibly be negative, so no atan ambiguity) + + 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 = atan( yh/xh ); + //resolve atan ambiguity + if ( xh < 0.0 ) ELongRad += dms::PI; + + double rr = sqrt( xh*xh + yh*yh + zh*zh ); + ELatRad = atan( zh/rr ); //(rr can't possibly be negative, so no atan ambiguity) + + ep.longitude.setRadians( ELongRad ); + ep.latitude.setRadians( ELatRad ); + if ( Earth ) setRearth( Earth ); + + EclipticToEquatorial( num->obliquity() ); + nutate( num ); + aberrate( num ); + + return true; +} + +//Unused virtual function from KSPlanetBase +bool KSAsteroid::loadData() { return false; } + |