void KSPlanetBase::findPhase() {
/* Compute the phase of the planet in degrees */
double earthSun = KStarsData::Instance()->skyComposite()->earth()->rsun();
double cosPhase = (rsun()*rsun() + rearth()*rearth() - earthSun*earthSun)
/ (2 * rsun() * rearth() );
Phase = acos ( cosPhase ) * 180.0 / dms::PI;
/* More elegant way of doing it, but requires the Sun.
TODO: Switch to this if and when we make KSSun a singleton */
// Phase = ecLong()->Degrees() - Sun->ecLong()->Degrees();
}
void KSPlanetBase::findMagnitude(const KSNumbers *num) {
double cosDec, sinDec;
dec()->SinCos(cosDec, sinDec);
/* Phase of the planet in degrees */
double earthSun = 1.;
double cosPhase = (rsun()*rsun() + rearth()*rearth() - earthSun*earthSun)
/ (2 * rsun() * rearth() );
double phase = acos ( cosPhase ) * 180.0 / dms::PI;
/* Computation of the visual magnitude (V band) of the planet.
* Algorithm provided by Pere Planesas (Observatorio Astronomico Nacional)
* It has some simmilarity to J. Meeus algorithm in Astronomical Algorithms, Chapter 40.
* */
// Initialized to the faintest magnitude observable with the HST
float magnitude = 30;
double param = 5 * log10(rsun() * rearth() );
double f1 = phase/100.;
if ( name() == "Mercury" ) {
if ( phase > 150. ) f1 = 1.5;
magnitude = -0.36 + param + 3.8*f1 - 2.73*f1*f1 + 2*f1*f1*f1;
}
if ( name() =="Venus")
magnitude = -4.29 + param + 0.09*f1 + 2.39*f1*f1 - 0.65*f1*f1*f1;
if( name() == "Mars")
magnitude = -1.52 + param + 0.016*phase;
if( name() == "Jupiter")
magnitude = -9.25 + param + 0.005*phase;
if( name() == "Saturn") {
double T = num->julianCenturies();
double a0 = (40.66-4.695*T)* dms::PI / 180.;
double d0 = (83.52+0.403*T)* dms::PI / 180.;
double sinx = -cos(d0)*cosDec*cos(a0 - ra()->radians());
sinx = fabs(sinx-sin(d0)*sinDec);
double rings = -2.6*sinx + 1.25*sinx*sinx;
magnitude = -8.88 + param + 0.044*phase + rings;
}
if( name() == "Uranus")
magnitude = -7.19 + param + 0.0028*phase;
if( name() == "Neptune")
magnitude = -6.87 + param;
if( name() == "Pluto" )
magnitude = -1.01 + param + 0.041*phase;
setMag(magnitude);
}
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 KSPluto::findMagnitude(const KSNumbers*)
{
setMag( -1.01 + 5*log10(rsun() * rearth()) + 0.041*phase().Degrees() );
}
