private static void CalculateSetHelper(ref AASRiseTransitSetDetails details, double theta0, double deltaT, double Alpha1, double Delta1, double Alpha2, double Delta2, double Alpha3, double Delta3, double Longitude, double Latitude, double LatitudeRad, double h0, ref double M2)
{
for (int i = 0; i < 2; i++)
{
//Calculate the details of setting
if (details.bSetValid)
{
double theta1 = theta0 + 360.985647 * M2;
theta1 = AASCoordinateTransformation.MapTo0To360Range(theta1);
double n = M2 + deltaT / 86400;
double Alpha = AASInterpolate.Interpolate(n, Alpha1, Alpha2, Alpha3);
double Delta = AASInterpolate.Interpolate(n, Delta1, Delta2, Delta3);
double H = theta1 - Longitude - Alpha * 15;
AAS2DCoordinate Horizontal = AASCoordinateTransformation.Equatorial2Horizontal(H / 15, Delta, Latitude);
double DeltaM = (Horizontal.Y - h0) / (360 * Math.Cos(AASCoordinateTransformation.DegreesToRadians(Delta)) * Math.Cos(LatitudeRad) * Math.Sin(AASCoordinateTransformation.DegreesToRadians(H)));
M2 += DeltaM;
if ((M2 < 0) || (M2 >= 1))
{
details.bSetValid = false;
}
}
}
}
public static AASRiseTransitSetDetails Calculate(double JD, double Alpha1, double Delta1, double Alpha2, double Delta2, double Alpha3, double Delta3, double Longitude, double Latitude, double h0)
{
//What will be the return value
AASRiseTransitSetDetails details = new AASRiseTransitSetDetails();
details.bRiseValid = false;
details.bSetValid = false;
details.bTransitAboveHorizon = false;
//Calculate the sidereal time
double theta0 = AASSidereal.ApparentGreenwichSiderealTime(JD);
theta0 *= 15; //Express it as degrees
//Calculate deltat
double deltaT = AASDynamicalTime.DeltaT(JD);
//Convert values to radians
double Delta2Rad = AASCoordinateTransformation.DegreesToRadians(Delta2);
double LatitudeRad = AASCoordinateTransformation.DegreesToRadians(Latitude);
//Convert the standard latitude to radians
double h0Rad = AASCoordinateTransformation.DegreesToRadians(h0);
double cosH0 = (Math.Sin(h0Rad) - Math.Sin(LatitudeRad) * Math.Sin(Delta2Rad)) / (Math.Cos(LatitudeRad) * Math.Cos(Delta2Rad));
//Calculate and ensure the M0 is in the range 0 to +1
double M0 = (Alpha2 * 15 + Longitude - theta0) / 360;
while (M0 > 1)
{
M0 -= 1;
}
while (M0 < 0)
{
M0 += 1;
}
//Check that the object actually rises
double M1 = 0;
double M2 = 0;
if ((cosH0 > -1) && (cosH0 < 1))
{
details.bRiseValid = true;
details.bSetValid = true;
details.bTransitAboveHorizon = true;
double H0 = Math.Acos(cosH0);
H0 = AASCoordinateTransformation.RadiansToDegrees(H0);
//Calculate and ensure the M1 and M2 is in the range 0 to +1
M1 = M0 - H0 / 360;
M2 = M0 + H0 / 360;
while (M1 > 1)
{
M1 -= 1;
}
while (M1 < 0)
{
M1 += 1;
}
while (M2 > 1)
{
M2 -= 1;
}
while (M2 < 0)
{
M2 += 1;
}
}
else
if (cosH0 < 1)
{
details.bTransitAboveHorizon = true;
}
//Ensure the RA values are corrected for interpolation. Due to important Remark 2 by Meeus on Interopolation of RA values
if ((Alpha2 - Alpha1) > 12.0)
{
Alpha1 += 24;
}
else
if ((Alpha2 - Alpha1) < -12.0)
{
Alpha2 += 24;
}
if ((Alpha3 - Alpha2) > 12.0)
{
Alpha2 += 24;
}
else
if ((Alpha3 - Alpha2) < -12.0)
{
Alpha3 += 24;
}
for (int i = 0; i < 2; i++)
{
//Calculate the details of rising
if (details.bRiseValid)
{
double theta1 = theta0 + 360.985647 * M1;
theta1 = AASCoordinateTransformation.MapTo0To360Range(theta1);
double n = M1 + deltaT / 86400;
double Alpha = AASInterpolate.Interpolate(n, Alpha1, Alpha2, Alpha3);
double Delta = AASInterpolate.Interpolate(n, Delta1, Delta2, Delta3);
double H = theta1 - Longitude - Alpha * 15;
AAS2DCoordinate Horizontal = AASCoordinateTransformation.Equatorial2Horizontal(H / 15, Delta, Latitude);
double DeltaM = (Horizontal.Y - h0) / (360 * Math.Cos(AASCoordinateTransformation.DegreesToRadians(Delta)) * Math.Cos(LatitudeRad) * Math.Sin(AASCoordinateTransformation.DegreesToRadians(H)));
M1 += DeltaM;
}
//Calculate the details of setting
if (details.bSetValid)
{
double theta1 = theta0 + 360.985647 * M2;
theta1 = AASCoordinateTransformation.MapTo0To360Range(theta1);
double n = M2 + deltaT / 86400;
double Alpha = AASInterpolate.Interpolate(n, Alpha1, Alpha2, Alpha3);
double Delta = AASInterpolate.Interpolate(n, Delta1, Delta2, Delta3);
double H = theta1 - Longitude - Alpha * 15;
AAS2DCoordinate Horizontal = AASCoordinateTransformation.Equatorial2Horizontal(H / 15, Delta, Latitude);
double DeltaM = (Horizontal.Y - h0) / (360 * Math.Cos(AASCoordinateTransformation.DegreesToRadians(Delta)) * Math.Cos(LatitudeRad) * Math.Sin(AASCoordinateTransformation.DegreesToRadians(H)));
M2 += DeltaM;
}
{
//Calculate the details of transit
double theta1 = theta0 + 360.985647 * M0;
theta1 = AASCoordinateTransformation.MapTo0To360Range(theta1);
double n = M0 + deltaT / 86400;
double Alpha = AASInterpolate.Interpolate(n, Alpha1, Alpha2, Alpha3);
double H = theta1 - Longitude - Alpha * 15;
H = AASCoordinateTransformation.MapTo0To360Range(H);
if (H > 180)
{
H -= 360;
}
double DeltaM = -H / 360;
M0 += DeltaM;
}
}
details.Rise = details.bRiseValid ? (M1 * 24) : 0.0;
details.Set = details.bSetValid ? (M2 * 24) : 0.0;
details.Transit = M0 * 24; //We always return the transit time even if it occurs below the horizon
return(details);
}