private static void CalculateTransitHelper(ref AASRiseTransitSetDetails details, double theta0, double deltaT, double Alpha1, double Alpha2, double Alpha3, double Longitude, ref double M0)
        {
            for (int i = 0; i < 2; i++)
            {
                //Calculate the details of transit
                if (details.bTransitValid)
                {
                    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;

                    if (M0 < 0 || M0 >= 1)
                    {
                        details.bTransitValid = false;
                    }
                }
            }
        }
        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;
                    }
                }
            }
        }
Example #3
0
        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);
        }