/// <summary>
/// Based on Chapter 39, Meeus and Chapter 10
/// </summary>
/// <param name="obs"></param>
public void makeTopocentric(GPObserver obs)
{
double u, h, delta_alpha;
double rho_sin, rho_cos;
const double b_a = 0.99664719;
// geocentric position of observer on the earth surface
// 10.1 - 10.3
u = GPMath.arctanDeg(b_a * b_a * GPMath.tanDeg(obs.GetLatitudeNorthPositive()));
rho_sin = b_a * GPMath.sinDeg(u) + obs.GetAltitude() / 6378140.0 * GPMath.sinDeg(obs.GetLatitudeNorthPositive());
rho_cos = GPMath.cosDeg(u) + obs.GetAltitude() / 6378140.0 * GPMath.cosDeg(obs.GetLatitudeNorthPositive());
// equatorial horizontal paralax
// 39.1
this.parallax = GPMath.arcsinDeg(GPMath.sinDeg(8.794 / 3600) / (this.distanceFromEarth / GPAstroEngine.AU));
// geocentric hour angle of the body
h = apparent_sidereal_time - obs.GetLongitudeWestPositive() - right_ascession;
// 39.2
delta_alpha = GPMath.arctanDeg(
(-rho_cos * GPMath.sinDeg(this.parallax) * GPMath.sinDeg(h)) /
(GPMath.cosDeg(this.declination) - rho_cos * GPMath.sinDeg(this.parallax) * GPMath.cosDeg(h)));
this.right_ascession += delta_alpha;
this.declination = GPMath.arctanDeg(
((GPMath.sinDeg(this.declination) - rho_sin * GPMath.sinDeg(this.parallax)) * GPMath.cosDeg(delta_alpha)) /
(GPMath.cosDeg(this.declination) - rho_cos * GPMath.sinDeg(this.parallax) * GPMath.cosDeg(h)));
}
private void calculateRiseSetMethodA(GPGregorianTime vct, GPLocationProvider ed, double DayHours, GPSun sun, double DG, double RAD)
{
double time = vct.getJulianLocalNoon() - 0.5 + DayHours / 360 - vct.getTimeZoneOffsetHours() / 24.0;
double dLatitude = ed.getLocation(time).GetLatitudeNorthPositive();
double dLongitude = ed.getLocation(time).GetLongitudeEastPositive();
//Debugger.Log(0,"",String.Format("{0} {1} {2}\n", vct.getLongDateString(), dLatitude, dLongitude));
// definition of event
// eventdef = 0.0;
// civil twilight eventdef = 0.10453;
// nautical twilight eventdef = 0.20791;
// astronomical twilight eventdef = 0.30902;
// center of the sun on the horizont eventdef = 0.01454;
double eventdef = 0.01454;
double x = GPMath.tanDeg(dLatitude) * GPMath.tanDeg(sun.declination) + eventdef / (GPMath.cosDeg(dLatitude) * GPMath.cosDeg(sun.declination));
if (x < -1.0 || x > 1.0)
{
// initial values for the case
// that no rise no set for that day
sun.sunrise_deg = -360;
sun.noon_deg = -360;
sun.sunset_deg = -360;
return;
}
double hourAngle = GPMath.arcsinDeg(x);
// time of sunrise
sun.sunrise_deg = 90.0 - dLongitude - hourAngle + equationOfTime;
// time of noon
sun.noon_deg = 180.0 - dLongitude + equationOfTime;
// time of sunset
sun.sunset_deg = 270.0 - dLongitude + hourAngle + equationOfTime;
}
public static void calc_geocentric(ref double longitude, ref double latitude, ref double rektaszension, ref double declination, double date)
{
//var
double epsilon; //: extended;
double delta_phi; //: extended;
double alpha, delta; //: extended;
calc_epsilon_phi(date, out delta_phi, out epsilon);
longitude = GPMath.putIn360(longitude + delta_phi);
alpha = GPMath.arctan2Deg(GPMath.sinDeg(longitude) * GPMath.cosDeg(epsilon) - GPMath.tanDeg(latitude) * GPMath.sinDeg(epsilon), GPMath.cosDeg(longitude));
delta = GPMath.arcsinDeg(GPMath.sinDeg(latitude) * GPMath.cosDeg(epsilon) + GPMath.cosDeg(latitude) * GPMath.sinDeg(epsilon) * GPMath.sinDeg(longitude));
rektaszension = alpha;
declination = delta;
double xg, yg, zg;
xg = GPMath.cosDeg(longitude) * GPMath.cosDeg(latitude);
yg = GPMath.sinDeg(longitude) * GPMath.cosDeg(latitude);
zg = GPMath.sinDeg(latitude);
alpha = GPMath.arctan2Deg(yg * GPMath.cosDeg(epsilon) - zg * GPMath.sinDeg(epsilon), GPMath.cosDeg(longitude) * GPMath.cosDeg(latitude));
}