// Time not used in current calculation, but might be need in future refinements public static EquatorialCoordinate From(EclipticCoordinate eclipticCoordinate, Time time) { // Calculate right ascension and declination Angle angleEpsilon = Angle.FromDegrees(23.4392911); // obliquity of the ecliptic -- see Meeus, pg. 92 Angle angleRightAscension = Angle.ArcTangent(eclipticCoordinate.Longitude.Sine * angleEpsilon.Cosine - eclipticCoordinate.Latitude.Tangent * angleEpsilon.Sine, eclipticCoordinate.Longitude.Cosine); angleRightAscension.NormalizePositive(); Angle angleDeclination = Angle.Zero; angleDeclination.Sine = eclipticCoordinate.Latitude.Sine * angleEpsilon.Cosine + eclipticCoordinate.Latitude.Cosine * angleEpsilon.Sine * eclipticCoordinate.Longitude.Sine; angleDeclination.NormalizeAroundZero(); return(new EquatorialCoordinate(angleRightAscension, angleDeclination)); }
public static HorizontalCoordinate From(EquatorialCoordinate equatorialCoordinate, GeographicCoordinate geographicCoordinate, Time time) { // Calculate hour angle Angle localHourAngle = time.GreenwichSiderealTime - geographicCoordinate.Longitude - equatorialCoordinate.RightAscension; // Calculate azimuth Angle azimuth = Angle.ArcTangent(localHourAngle.Sine, localHourAngle.Cosine * geographicCoordinate.Latitude.Sine - equatorialCoordinate.Declination.Tangent * geographicCoordinate.Latitude.Cosine); // Adjustment for azimuth eastward from north azimuth += Angle.Straight; azimuth.NormalizeAroundZero(); // Calculate altitude Angle altitude = Angle.Zero; altitude.Sine = geographicCoordinate.Latitude.Sine * equatorialCoordinate.Declination.Sine + geographicCoordinate.Latitude.Cosine * equatorialCoordinate.Declination.Cosine * localHourAngle.Cosine; altitude.NormalizeAroundZero(); return(new HorizontalCoordinate(azimuth, altitude)); }