public static double SiderealTimeGreenwich(double date)
{
double jd, t;
double delta_phi = 0.0, epsilon = 0.0;
jd = date;
t = (jd - 2451545.0) / 36525.0;
GCEarthData.CalculateNutations(date, out delta_phi, out epsilon);
return(GCMath.putIn360(280.46061837 + 360.98564736629 * (jd - 2451545.0) +
t * t * (0.000387933 - t / 38710000) +
delta_phi * GCMath.cosDeg(epsilon)));
}
/// <summary>
///
/// </summary>
/// <param name="julianDateUTC">Time in UT1 or for general use UTC. This should reflect also hours, minutes and seconds. When finding local sidereal time,
/// this argument should contains time that is observed on Greenwich meridian. Use function GetJulianDetailed or GetGreenwichDateTime</param>
/// <param name="longitudeDegrees"></param>
/// <returns></returns>
public static double SiderealTimeLocal(double julianDateUTC, double longitudeDegrees, double timezoneDegrees)
{
double julianDate2000, julianMillenium;
double delta_phi = 0.0, epsilon = 0.0;
julianDate2000 = julianDateUTC - 2451545.0;
julianMillenium = julianDate2000 / 36525.0;
GCEarthData.CalculateNutations(julianDateUTC, out delta_phi, out epsilon);
return(GCMath.putIn360(280.46061837 + 360.98564736629 * julianDate2000 +
julianMillenium * julianMillenium * (0.000387933 - julianMillenium / 38710000) +
delta_phi * GCMath.cosDeg(epsilon) + longitudeDegrees - timezoneDegrees));
}
public static GCEquatorialCoords eclipticalToEquatorialCoords(ref GCEclipticalCoords ecc, double date)
{
//var
GCEquatorialCoords eqc;
double epsilon;
double nutationLongitude;
GCEarthData.CalculateNutations(date, out nutationLongitude, out epsilon);
// formula from Chapter 21
ecc.longitude = GCMath.putIn360(ecc.longitude + nutationLongitude);
// formulas from Chapter 12
eqc.rightAscension = GCMath.arcTan2Deg(GCMath.sinDeg(ecc.longitude) * GCMath.cosDeg(epsilon) - GCMath.tanDeg(ecc.latitude) * GCMath.sinDeg(epsilon),
GCMath.cosDeg(ecc.longitude));
eqc.declination = GCMath.arcSinDeg(GCMath.sinDeg(ecc.latitude) * GCMath.cosDeg(epsilon) + GCMath.cosDeg(ecc.latitude) * GCMath.sinDeg(epsilon) * GCMath.sinDeg(ecc.longitude));
return(eqc);
}
