Ejemplo n.º 1
0
        public static AASPhysicalSunDetails Calculate(double JD)
        {
            double theta = AASCoordinateTransformation.MapTo0To360Range((JD - 2398220) * 360 / 25.38);
            double I     = 7.25;
            double K     = 73.6667 + 1.3958333 * (JD - 2396758) / 36525;

            //Calculate the apparent longitude of the sun (excluding the effect of nutation)
            double L       = AASEarth.EclipticLongitude(JD);
            double R       = AASEarth.RadiusVector(JD);
            double SunLong = L + 180 - AASCoordinateTransformation.DMSToDegrees(0, 0, 20.4898 / R);

            double epsilon = AASNutation.TrueObliquityOfEcliptic(JD);

            //Convert to radians
            epsilon = AASCoordinateTransformation.DegreesToRadians(epsilon);
            SunLong = AASCoordinateTransformation.DegreesToRadians(SunLong);
            K       = AASCoordinateTransformation.DegreesToRadians(K);
            I       = AASCoordinateTransformation.DegreesToRadians(I);
            theta   = AASCoordinateTransformation.DegreesToRadians(theta);

            double x = Math.Atan(-Math.Cos(SunLong) * Math.Tan(epsilon));
            double y = Math.Atan(-Math.Cos(SunLong - K) * Math.Tan(I));

            AASPhysicalSunDetails details = new AASPhysicalSunDetails();

            details.P  = AASCoordinateTransformation.RadiansToDegrees(x + y);
            details.B0 = AASCoordinateTransformation.RadiansToDegrees(Math.Asin(Math.Sin(SunLong - K) * Math.Sin(I)));

            double eta = Math.Atan(Math.Tan(SunLong - K) * Math.Cos(I));

            details.L0 = AASCoordinateTransformation.MapTo0To360Range(AASCoordinateTransformation.RadiansToDegrees(eta - theta));

            return(details);
        }
Ejemplo n.º 2
0
        public static double Calculate(double JD)
        {
            double rho        = (JD - 2451545) / 365250;
            double rhosquared = rho * rho;
            double rhocubed   = rhosquared * rho;
            double rho4       = rhocubed * rho;
            double rho5       = rho4 * rho;

            //Calculate the Suns mean longitude
            double L0 = AASCoordinateTransformation.MapTo0To360Range(280.4664567 + 360007.6982779 * rho + 0.03032028 * rhosquared +
                                                                     rhocubed / 49931 - rho4 / 15300 - rho5 / 2000000);

            //Calculate the Suns apparent right ascension
            double          SunLong    = AASSun.ApparentEclipticLongitude(JD);
            double          SunLat     = AASSun.ApparentEclipticLatitude(JD);
            double          epsilon    = AASNutation.TrueObliquityOfEcliptic(JD);
            AAS2DCoordinate Equatorial = AASCoordinateTransformation.Ecliptic2Equatorial(SunLong, SunLat, epsilon);

            epsilon = AASCoordinateTransformation.DegreesToRadians(epsilon);
            double E = L0 - 0.0057183 - Equatorial.X * 15 + AASCoordinateTransformation.DMSToDegrees(0, 0, AASNutation.NutationInLongitude(JD)) * Math.Cos(epsilon);

            if (E > 180)
            {
                E = -(360 - E);
            }
            E *= 4; //Convert to minutes of time

            return(E);
        }
Ejemplo n.º 3
0
        public static double EclipticLongitude(double JD)
        {
            double Ldash        = MeanLongitude(JD);
            double LdashDegrees = Ldash;

            Ldash = AASCoordinateTransformation.DegreesToRadians(Ldash);
            double D = MeanElongation(JD);

            D = AASCoordinateTransformation.DegreesToRadians(D);
            double M = AASEarth.SunMeanAnomaly(JD);

            M = AASCoordinateTransformation.DegreesToRadians(M);
            double Mdash = MeanAnomaly(JD);

            Mdash = AASCoordinateTransformation.DegreesToRadians(Mdash);
            double F = ArgumentOfLatitude(JD);

            F = AASCoordinateTransformation.DegreesToRadians(F);

            double E        = AASEarth.Eccentricity(JD);
            double Esquared = E * E;
            double T        = (JD - 2451545) / 36525;

            double A1 = AASCoordinateTransformation.MapTo0To360Range(119.75 + 131.849 * T);

            A1 = AASCoordinateTransformation.DegreesToRadians(A1);
            double A2 = AASCoordinateTransformation.MapTo0To360Range(53.09 + 479264.290 * T);

            A2 = AASCoordinateTransformation.DegreesToRadians(A2);

            int    nLCoefficients = g_MoonCoefficients1.Length;
            double SigmaL         = 0;

            for (int i = 0; i < nLCoefficients; i++)
            {
                double ThisSigma = g_MoonCoefficients2[i].A * Math.Sin(g_MoonCoefficients1[i].D * D + g_MoonCoefficients1[i].M * M +
                                                                       g_MoonCoefficients1[i].Mdash * Mdash + g_MoonCoefficients1[i].F * F);

                if ((g_MoonCoefficients1[i].M == 1) || (g_MoonCoefficients1[i].M == -1))
                {
                    ThisSigma *= E;
                }
                else if ((g_MoonCoefficients1[i].M == 2) || (g_MoonCoefficients1[i].M == -2))
                {
                    ThisSigma *= Esquared;
                }

                SigmaL += ThisSigma;
            }

            //Finally the additive terms
            SigmaL += 3958 * Math.Sin(A1);
            SigmaL += 1962 * Math.Sin(Ldash - F);
            SigmaL += 318 * Math.Sin(A2);

            //And finally apply the nutation in longitude
            double NutationInLong = AASNutation.NutationInLongitude(JD);

            return(AASCoordinateTransformation.MapTo0To360Range(LdashDegrees + SigmaL / 1000000 + NutationInLong / 3600));
        }
        public static double ApparentGreenwichSiderealTime(double JD)
        {
            double MeanObliquity       = AASNutation.MeanObliquityOfEcliptic(JD);
            double TrueObliquity       = MeanObliquity + AASNutation.NutationInObliquity(JD) / 3600;
            double NutationInLongitude = AASNutation.NutationInLongitude(JD);

            double Value = MeanGreenwichSiderealTime(JD) + (NutationInLongitude * Math.Cos(AASCoordinateTransformation.DegreesToRadians(TrueObliquity)) / 54000);

            return(AASCoordinateTransformation.MapTo0To24Range(Value));
        }
Ejemplo n.º 5
0
        public static double ApparentEclipticLongitude(double JD)
        {
            double Longitude = GeometricFK5EclipticLongitude(JD);

            //Apply the correction in longitude due to nutation
            Longitude += AASCoordinateTransformation.DMSToDegrees(0, 0, AASNutation.NutationInLongitude(JD));

            //Apply the correction in longitude due to aberration
            double R = AASEarth.RadiusVector(JD);

            Longitude -= AASCoordinateTransformation.DMSToDegrees(0, 0, 20.4898 / R);

            return(Longitude);
        }
Ejemplo n.º 6
0
        public static AAS3DCoordinate EquatorialRectangularCoordinatesMeanEquinox(double JD, bool bHighPrecision)
        {
            double Longitude = AASCoordinateTransformation.DegreesToRadians(GeometricFK5EclipticLongitude(JD, bHighPrecision));
            double Latitude  = AASCoordinateTransformation.DegreesToRadians(GeometricFK5EclipticLatitude(JD, bHighPrecision));
            double R         = AASEarth.RadiusVector(JD, bHighPrecision);
            double epsilon   = AASCoordinateTransformation.DegreesToRadians(AASNutation.MeanObliquityOfEcliptic(JD));

            AAS3DCoordinate value = new AAS3DCoordinate
            {
                X = R * Math.Cos(Latitude) * Math.Cos(Longitude),
                Y = R * (Math.Cos(Latitude) * Math.Sin(Longitude) * Math.Cos(epsilon) - Math.Sin(Latitude) * Math.Sin(epsilon)),
                Z = R * (Math.Cos(Latitude) * Math.Sin(Longitude) * Math.Sin(epsilon) + Math.Sin(Latitude) * Math.Cos(epsilon))
            };

            return(value);
        }
Ejemplo n.º 7
0
        public static double ApparentEclipticLongitude(double JD, bool bHighPrecision)
        {
            double Longitude = GeometricFK5EclipticLongitude(JD, bHighPrecision);

            //Apply the correction in longitude due to nutation
            Longitude += AASCoordinateTransformation.DMSToDegrees(0, 0, AASNutation.NutationInLongitude(JD));

            //Apply the correction in longitude due to aberration
            double R = AASEarth.RadiusVector(JD, bHighPrecision);

            if (bHighPrecision)
            {
                Longitude -= (0.005775518 * R * AASCoordinateTransformation.DMSToDegrees(0, 0, VariationGeometricEclipticLongitude(JD)));
            }
            else
            {
                Longitude -= AASCoordinateTransformation.DMSToDegrees(0, 0, 20.4898 / R);
            }

            return(Longitude);
        }
Ejemplo n.º 8
0
        public static void CalculateOpticalLibration(double JD, double Lambda, double Beta, ref double ldash, ref double bdash, ref double ldash2, ref double bdash2, ref double epsilon, ref double omega, ref double DeltaU, ref double sigma, ref double I, ref double rho)
        {
            //Calculate the initial quantities
            double Lambdarad = AASCoordinateTransformation.DegreesToRadians(Lambda);
            double Betarad   = AASCoordinateTransformation.DegreesToRadians(Beta);

            I      = AASCoordinateTransformation.DegreesToRadians(1.54242);
            DeltaU = AASCoordinateTransformation.DegreesToRadians(AASNutation.NutationInLongitude(JD) / 3600);
            double F = AASCoordinateTransformation.DegreesToRadians(AASMoon.ArgumentOfLatitude(JD));

            omega   = AASCoordinateTransformation.DegreesToRadians(AASMoon.MeanLongitudeAscendingNode(JD));
            epsilon = AASNutation.MeanObliquityOfEcliptic(JD) + AASNutation.NutationInObliquity(JD) / 3600;

            //Calculate the optical librations
            double W = Lambdarad - DeltaU / 3600 - omega;
            double A = Math.Atan2(Math.Sin(W) * Math.Cos(Betarad) * Math.Cos(I) - Math.Sin(Betarad) * Math.Sin(I), Math.Cos(W) * Math.Cos(Betarad));

            ldash = AASCoordinateTransformation.MapTo0To360Range(AASCoordinateTransformation.RadiansToDegrees(A) - AASCoordinateTransformation.RadiansToDegrees(F));
            if (ldash > 180)
            {
                ldash -= 360;
            }
            bdash = Math.Asin(-Math.Sin(W) * Math.Cos(Betarad) * Math.Sin(I) - Math.Sin(Betarad) * Math.Cos(I));

            //Calculate the physical librations
            double T  = (JD - 2451545.0) / 36525;
            double K1 = 119.75 + 131.849 * T;

            K1 = AASCoordinateTransformation.DegreesToRadians(K1);
            double K2 = 72.56 + 20.186 * T;

            K2 = AASCoordinateTransformation.DegreesToRadians(K2);

            double M = AASEarth.SunMeanAnomaly(JD);

            M = AASCoordinateTransformation.DegreesToRadians(M);
            double Mdash = AASMoon.MeanAnomaly(JD);

            Mdash = AASCoordinateTransformation.DegreesToRadians(Mdash);
            double D = AASMoon.MeanElongation(JD);

            D = AASCoordinateTransformation.DegreesToRadians(D);
            double E = AASEarth.Eccentricity(JD);

            rho = -0.02752 * Math.Cos(Mdash) +
                  -0.02245 * Math.Sin(F) +
                  0.00684 * Math.Cos(Mdash - 2 * F) +
                  -0.00293 * Math.Cos(2 * F) +
                  -0.00085 * Math.Cos(2 * F - 2 * D) +
                  -0.00054 * Math.Cos(Mdash - 2 * D) +
                  -0.00020 * Math.Sin(Mdash + F) +
                  -0.00020 * Math.Cos(Mdash + 2 * F) +
                  -0.00020 * Math.Cos(Mdash - F) +
                  0.00014 * Math.Cos(Mdash + 2 * F - 2 * D);

            sigma = -0.02816 * Math.Sin(Mdash) +
                    0.02244 * Math.Cos(F) +
                    -0.00682 * Math.Sin(Mdash - 2 * F) +
                    -0.00279 * Math.Sin(2 * F) +
                    -0.00083 * Math.Sin(2 * F - 2 * D) +
                    0.00069 * Math.Sin(Mdash - 2 * D) +
                    0.00040 * Math.Cos(Mdash + F) +
                    -0.00025 * Math.Sin(2 * Mdash) +
                    -0.00023 * Math.Sin(Mdash + 2 * F) +
                    0.00020 * Math.Cos(Mdash - F) +
                    0.00019 * Math.Sin(Mdash - F) +
                    0.00013 * Math.Sin(Mdash + 2 * F - 2 * D) +
                    -0.00010 * Math.Cos(Mdash - 3 * F);

            double tau = 0.02520 * E * Math.Sin(M) +
                         0.00473 * Math.Sin(2 * Mdash - 2 * F) +
                         -0.00467 * Math.Sin(Mdash) +
                         0.00396 * Math.Sin(K1) +
                         0.00276 * Math.Sin(2 * Mdash - 2 * D) +
                         0.00196 * Math.Sin(omega) +
                         -0.00183 * Math.Cos(Mdash - F) +
                         0.00115 * Math.Sin(Mdash - 2 * D) +
                         -0.00096 * Math.Sin(Mdash - D) +
                         0.00046 * Math.Sin(2 * F - 2 * D) +
                         -0.00039 * Math.Sin(Mdash - F) +
                         -0.00032 * Math.Sin(Mdash - M - D) +
                         0.00027 * Math.Sin(2 * Mdash - M - 2 * D) +
                         0.00023 * Math.Sin(K2) +
                         -0.00014 * Math.Sin(2 * D) +
                         0.00014 * Math.Cos(2 * Mdash - 2 * F) +
                         -0.00012 * Math.Sin(Mdash - 2 * F) +
                         -0.00012 * Math.Sin(2 * Mdash) +
                         0.00011 * Math.Sin(2 * Mdash - 2 * M - 2 * D);

            ldash2 = -tau + (rho * Math.Cos(A) + sigma * Math.Sin(A)) * Math.Tan(bdash);
            bdash  = AASCoordinateTransformation.RadiansToDegrees(bdash);
            bdash2 = sigma * Math.Cos(A) - rho * Math.Sin(A);
        }
        public static CAAPhysicalMarsDetails Calculate(double JD, bool bHighPrecision)
        {
            //What will be the return value
            CAAPhysicalMarsDetails details = new CAAPhysicalMarsDetails();

            //Step 1
            double T          = (JD - 2451545) / 36525;
            double Lambda0    = 352.9065 + 1.17330 * T;
            double Lambda0rad = AASCoordinateTransformation.DegreesToRadians(Lambda0);
            double Beta0      = 63.2818 - 0.00394 * T;
            double Beta0rad   = AASCoordinateTransformation.DegreesToRadians(Beta0);

            //Step 2
            double l0    = AASEarth.EclipticLongitude(JD, bHighPrecision);
            double l0rad = AASCoordinateTransformation.DegreesToRadians(l0);
            double b0    = AASEarth.EclipticLatitude(JD, bHighPrecision);
            double b0rad = AASCoordinateTransformation.DegreesToRadians(b0);
            double R     = AASEarth.RadiusVector(JD, bHighPrecision);

            double PreviousLightTravelTime = 0;
            double LightTravelTime         = 0;
            double x        = 0;
            double y        = 0;
            double z        = 0;
            bool   bIterate = true;
            double DELTA    = 0;
            double l        = 0;
            double lrad     = 0;
            double b        = 0;
            double r        = 0;

            while (bIterate)
            {
                double JD2 = JD - LightTravelTime;

                //Step 3
                l    = AASMars.EclipticLongitude(JD2, bHighPrecision);
                lrad = AASCoordinateTransformation.DegreesToRadians(l);
                b    = AASMars.EclipticLatitude(JD2, bHighPrecision);
                double brad = AASCoordinateTransformation.DegreesToRadians(b);
                r = AASMars.RadiusVector(JD2, bHighPrecision);

                //Step 4
                x               = r * Math.Cos(brad) * Math.Cos(lrad) - R * Math.Cos(l0rad);
                y               = r * Math.Cos(brad) * Math.Sin(lrad) - R * Math.Sin(l0rad);
                z               = r * Math.Sin(brad) - R * Math.Sin(b0rad);
                DELTA           = Math.Sqrt(x * x + y * y + z * z);
                LightTravelTime = AASElliptical.DistanceToLightTime(DELTA);

                //Prepare for the next loop around
                bIterate = (Math.Abs(LightTravelTime - PreviousLightTravelTime) > 2E-6); //2E-6 correponds to 0.17 of a second
                if (bIterate)
                {
                    PreviousLightTravelTime = LightTravelTime;
                }
            }

            //Step 5
            double lambdarad = Math.Atan2(y, x);
            double lambda    = AASCoordinateTransformation.RadiansToDegrees(lambdarad);
            double betarad   = Math.Atan2(z, Math.Sqrt(x * x + y * y));
            double beta      = AASCoordinateTransformation.RadiansToDegrees(betarad);

            //Step 6
            details.DE = AASCoordinateTransformation.RadiansToDegrees(Math.Asin(-Math.Sin(Beta0rad) * Math.Sin(betarad) - Math.Cos(Beta0rad) * Math.Cos(betarad) * Math.Cos(Lambda0rad - lambdarad)));

            //Step 7
            double N    = 49.5581 + 0.7721 * T;
            double Nrad = AASCoordinateTransformation.DegreesToRadians(N);

            double ldash    = l - 0.00697 / r;
            double ldashrad = AASCoordinateTransformation.DegreesToRadians(ldash);
            double bdash    = b - 0.000225 * (Math.Cos(lrad - Nrad) / r);
            double bdashrad = AASCoordinateTransformation.DegreesToRadians(bdash);

            //Step 8
            details.DS = AASCoordinateTransformation.RadiansToDegrees(Math.Asin(-Math.Sin(Beta0rad) * Math.Sin(bdashrad) - Math.Cos(Beta0rad) * Math.Cos(bdashrad) * Math.Cos(Lambda0rad - ldashrad)));

            //Step 9
            double W = AASCoordinateTransformation.MapTo0To360Range(11.504 + 350.89200025 * (JD - LightTravelTime - 2433282.5));

            //Step 10
            double          e0             = AASNutation.MeanObliquityOfEcliptic(JD);
            double          e0rad          = AASCoordinateTransformation.DegreesToRadians(e0);
            AAS2DCoordinate PoleEquatorial = AASCoordinateTransformation.Ecliptic2Equatorial(Lambda0, Beta0, e0);
            double          alpha0rad      = AASCoordinateTransformation.HoursToRadians(PoleEquatorial.X);
            double          delta0rad      = AASCoordinateTransformation.DegreesToRadians(PoleEquatorial.Y);

            //Step 11
            double u        = y * Math.Cos(e0rad) - z * Math.Sin(e0rad);
            double v        = y * Math.Sin(e0rad) + z * Math.Cos(e0rad);
            double alpharad = Math.Atan2(u, x);
            double alpha    = AASCoordinateTransformation.RadiansToHours(alpharad);
            double deltarad = Math.Atan2(v, Math.Sqrt(x * x + u * u));
            double delta    = AASCoordinateTransformation.RadiansToDegrees(deltarad);
            double xi       = Math.Atan2(Math.Sin(delta0rad) * Math.Cos(deltarad) * Math.Cos(alpha0rad - alpharad) - Math.Sin(deltarad) * Math.Cos(delta0rad), Math.Cos(deltarad) * Math.Sin(alpha0rad - alpharad));

            //Step 12
            details.w = AASCoordinateTransformation.MapTo0To360Range(W - AASCoordinateTransformation.RadiansToDegrees(xi));

            //Step 13
            double NutationInLongitude = AASNutation.NutationInLongitude(JD);
            double NutationInObliquity = AASNutation.NutationInObliquity(JD);

            //Step 14
            lambda += 0.005693 * Math.Cos(l0rad - lambdarad) / Math.Cos(betarad);
            beta   += 0.005693 * Math.Sin(l0rad - lambdarad) * Math.Sin(betarad);

            //Step 15
            Lambda0 += NutationInLongitude / 3600;
            lambda  += NutationInLongitude / 3600;
            e0      += NutationInObliquity / 3600;

            //Step 16
            AAS2DCoordinate ApparentPoleEquatorial = AASCoordinateTransformation.Ecliptic2Equatorial(Lambda0, Beta0, e0);
            double          alpha0dash             = AASCoordinateTransformation.HoursToRadians(ApparentPoleEquatorial.X);
            double          delta0dash             = AASCoordinateTransformation.DegreesToRadians(ApparentPoleEquatorial.Y);
            AAS2DCoordinate ApparentMars           = AASCoordinateTransformation.Ecliptic2Equatorial(lambda, beta, e0);
            double          alphadash = AASCoordinateTransformation.HoursToRadians(ApparentMars.X);
            double          deltadash = AASCoordinateTransformation.DegreesToRadians(ApparentMars.Y);

            //Step 17
            details.P = AASCoordinateTransformation.MapTo0To360Range(AASCoordinateTransformation.RadiansToDegrees(Math.Atan2(Math.Cos(delta0dash) * Math.Sin(alpha0dash - alphadash), Math.Sin(delta0dash) * Math.Cos(deltadash) - Math.Cos(delta0dash) * Math.Sin(deltadash) * Math.Cos(alpha0dash - alphadash))));

            //Step 18
            double          SunLambda     = AASSun.GeometricEclipticLongitude(JD, bHighPrecision);
            double          SunBeta       = AASSun.GeometricEclipticLatitude(JD, bHighPrecision);
            AAS2DCoordinate SunEquatorial = AASCoordinateTransformation.Ecliptic2Equatorial(SunLambda, SunBeta, e0);

            details.X = AASMoonIlluminatedFraction.PositionAngle(SunEquatorial.X, SunEquatorial.Y, alpha, delta);

            //Step 19
            details.d = 9.36 / DELTA;
            details.k = AASIlluminatedFraction.IlluminatedFraction(r, R, DELTA);
            details.q = (1 - details.k) * details.d;

            return(details);
        }
Ejemplo n.º 10
0
        public static AASNearParabolicObjectDetails Calculate(double JD, ref AASNearParabolicObjectElements elements, bool bHighPrecision)
        {
            double Epsilon = AASNutation.MeanObliquityOfEcliptic(elements.JDEquinox);

            double JD0 = JD;

            //What will be the return value
            AASNearParabolicObjectDetails details = new AASNearParabolicObjectDetails();

            Epsilon = AASCoordinateTransformation.DegreesToRadians(Epsilon);
            double omega = AASCoordinateTransformation.DegreesToRadians(elements.omega);
            double w     = AASCoordinateTransformation.DegreesToRadians(elements.w);
            double i     = AASCoordinateTransformation.DegreesToRadians(elements.i);

            double sinEpsilon = Math.Sin(Epsilon);
            double cosEpsilon = Math.Cos(Epsilon);
            double sinOmega   = Math.Sin(omega);
            double cosOmega   = Math.Cos(omega);
            double cosi       = Math.Cos(i);
            double sini       = Math.Sin(i);

            double F = cosOmega;
            double G = sinOmega * cosEpsilon;
            double H = sinOmega * sinEpsilon;
            double P = -sinOmega * cosi;
            double Q = cosOmega * cosi * cosEpsilon - sini * sinEpsilon;
            double R = cosOmega * cosi * sinEpsilon + sini * cosEpsilon;
            double a = Math.Sqrt(F * F + P * P);
            double b = Math.Sqrt(G * G + Q * Q);
            double c = Math.Sqrt(H * H + R * R);
            double A = Math.Atan2(F, P);
            double B = Math.Atan2(G, Q);
            double C = Math.Atan2(H, R);

            AAS3DCoordinate SunCoord = AASSun.EquatorialRectangularCoordinatesAnyEquinox(JD, elements.JDEquinox, bHighPrecision);

            for (int j = 0; j < 2; j++)
            {
                double v = 0;
                double r = 0;
                CalulateTrueAnnomalyAndRadius(JD0, ref elements, ref v, ref r);

                double x = r * a * Math.Sin(A + w + v);
                double y = r * b * Math.Sin(B + w + v);
                double z = r * c * Math.Sin(C + w + v);

                if (j == 0)
                {
                    details.HeliocentricRectangularEquatorial.X = x;
                    details.HeliocentricRectangularEquatorial.Y = y;
                    details.HeliocentricRectangularEquatorial.Z = z;

                    //Calculate the heliocentric ecliptic coordinates also
                    double u    = w + v;
                    double cosu = Math.Cos(u);
                    double sinu = Math.Sin(u);

                    details.HeliocentricRectangularEcliptical.X = r * (cosOmega * cosu - sinOmega * sinu * cosi);
                    details.HeliocentricRectangularEcliptical.Y = r * (sinOmega * cosu + cosOmega * sinu * cosi);
                    details.HeliocentricRectangularEcliptical.Z = r * sini * sinu;

                    details.HeliocentricEclipticLongitude = AASCoordinateTransformation.MapTo0To360Range(AASCoordinateTransformation.RadiansToDegrees(Math.Atan2(details.HeliocentricRectangularEcliptical.Y, details.HeliocentricRectangularEcliptical.X)));
                    details.HeliocentricEclipticLatitude  = AASCoordinateTransformation.RadiansToDegrees(Math.Asin(details.HeliocentricRectangularEcliptical.Z / r));
                }

                double psi   = SunCoord.X + x;
                double nu    = SunCoord.Y + y;
                double sigma = SunCoord.Z + z;

                double Alpha = Math.Atan2(nu, psi);
                Alpha = AASCoordinateTransformation.RadiansToDegrees(Alpha);
                double Delta = Math.Atan2(sigma, Math.Sqrt(psi * psi + nu * nu));
                Delta = AASCoordinateTransformation.RadiansToDegrees(Delta);
                double Distance = Math.Sqrt(psi * psi + nu * nu + sigma * sigma);

                if (j == 0)
                {
                    details.TrueGeocentricRA          = AASCoordinateTransformation.MapTo0To24Range(Alpha / 15);
                    details.TrueGeocentricDeclination = Delta;
                    details.TrueGeocentricDistance    = Distance;
                    details.TrueGeocentricLightTime   = AASElliptical.DistanceToLightTime(Distance);
                }
                else
                {
                    details.AstrometricGeocentricRA          = AASCoordinateTransformation.MapTo0To24Range(Alpha / 15);
                    details.AstrometricGeocentricDeclination = Delta;
                    details.AstrometricGeocentricDistance    = Distance;
                    details.AstrometricGeocentricLightTime   = AASElliptical.DistanceToLightTime(Distance);

                    double RES = Math.Sqrt(SunCoord.X * SunCoord.X + SunCoord.Y * SunCoord.Y + SunCoord.Z * SunCoord.Z);

                    details.Elongation = AASCoordinateTransformation.RadiansToDegrees(Math.Acos((RES * RES + Distance * Distance - r * r) / (2 * RES * Distance)));
                    details.PhaseAngle = AASCoordinateTransformation.RadiansToDegrees(Math.Acos((r * r + Distance * Distance - RES * RES) / (2 * r * Distance)));
                }

                if (j == 0) //Prepare for the next loop around
                {
                    JD0 = JD - details.TrueGeocentricLightTime;
                }
            }

            return(details);
        }
        public static AASSaturnRingDetails Calculate(double JD, bool bHighPrecision)
        {
            //What will be the return value
            AASSaturnRingDetails details = new AASSaturnRingDetails();

            double T  = (JD - 2451545) / 36525;
            double T2 = T * T;

            //Step 1. Calculate the inclination of the plane of the ring and the longitude of the ascending node referred to the ecliptic and mean equinox of the date
            double i        = 28.075216 - 0.012998 * T + 0.000004 * T2;
            double irad     = AASCoordinateTransformation.DegreesToRadians(i);
            double omega    = 169.508470 + 1.394681 * T + 0.000412 * T2;
            double omegarad = AASCoordinateTransformation.DegreesToRadians(omega);

            //Step 2. Calculate the heliocentric longitude, latitude and radius vector of the Earth in the FK5 system
            double l0 = AASEarth.EclipticLongitude(JD, bHighPrecision);
            double b0 = AASEarth.EclipticLatitude(JD, bHighPrecision);

            l0 += AASFK5.CorrectionInLongitude(l0, b0, JD);
            double l0rad = AASCoordinateTransformation.DegreesToRadians(l0);

            b0 += AASFK5.CorrectionInLatitude(l0, JD);
            double b0rad = AASCoordinateTransformation.DegreesToRadians(b0);
            double R     = AASEarth.RadiusVector(JD, bHighPrecision);

            //Step 3. Calculate the corresponding coordinates l,b,r for Saturn but for the instance t-lightraveltime
            double DELTA = 9;
            double PreviousEarthLightTravelTime = 0;
            double EarthLightTravelTime         = AASElliptical.DistanceToLightTime(DELTA);
            double JD1      = JD - EarthLightTravelTime;
            bool   bIterate = true;
            double x        = 0;
            double y        = 0;
            double z        = 0;
            double l        = 0;
            double b        = 0;
            double r        = 0;

            while (bIterate)
            {
                //Calculate the position of Saturn
                l  = AASSaturn.EclipticLongitude(JD1, bHighPrecision);
                b  = AASSaturn.EclipticLatitude(JD1, bHighPrecision);
                l += AASFK5.CorrectionInLongitude(l, b, JD1);
                b += AASFK5.CorrectionInLatitude(l, JD1);

                double lrad = AASCoordinateTransformation.DegreesToRadians(l);
                double brad = AASCoordinateTransformation.DegreesToRadians(b);
                r = AASSaturn.RadiusVector(JD1, bHighPrecision);

                //Step 4
                x     = r * Math.Cos(brad) * Math.Cos(lrad) - R * Math.Cos(l0rad);
                y     = r * Math.Cos(brad) * Math.Sin(lrad) - R * Math.Sin(l0rad);
                z     = r * Math.Sin(brad) - R * Math.Sin(b0rad);
                DELTA = Math.Sqrt(x * x + y * y + z * z);
                EarthLightTravelTime = AASElliptical.DistanceToLightTime(DELTA);

                //Prepare for the next loop around
                bIterate = (Math.Abs(EarthLightTravelTime - PreviousEarthLightTravelTime) > 2e-6); //2e-6 corresponds to 0.17 of a second
                if (bIterate)
                {
                    JD1 = JD - EarthLightTravelTime;
                    PreviousEarthLightTravelTime = EarthLightTravelTime;
                }
            }

            //Step 5. Calculate Saturn's geocentric Longitude and Latitude
            double lambda = Math.Atan2(y, x);
            double beta   = Math.Atan2(z, Math.Sqrt(x * x + y * y));

            //Step 6. Calculate B, a and b
            details.B = Math.Asin(Math.Sin(irad) * Math.Cos(beta) * Math.Sin(lambda - omegarad) - Math.Cos(irad) * Math.Sin(beta));
            details.a = 375.35 / DELTA;
            details.b = details.a * Math.Sin(Math.Abs(details.B));
            details.B = AASCoordinateTransformation.RadiansToDegrees(details.B);

            //Step 7. Calculate the longitude of the ascending node of Saturn's orbit
            double N        = 113.6655 + 0.8771 * T;
            double Nrad     = AASCoordinateTransformation.DegreesToRadians(N);
            double ldash    = l - 0.01759 / r;
            double ldashrad = AASCoordinateTransformation.DegreesToRadians(ldash);
            double bdash    = b - 0.000764 * Math.Cos(ldashrad - Nrad) / r;
            double bdashrad = AASCoordinateTransformation.DegreesToRadians(bdash);

            //Step 8. Calculate Bdash
            details.Bdash = AASCoordinateTransformation.RadiansToDegrees(Math.Asin(Math.Sin(irad) * Math.Cos(bdashrad) * Math.Sin(ldashrad - omegarad) - Math.Cos(irad) * Math.Sin(bdashrad)));

            //Step 9. Calculate DeltaU
            details.U1     = AASCoordinateTransformation.MapTo0To360Range(AASCoordinateTransformation.RadiansToDegrees(Math.Atan2(Math.Sin(irad) * Math.Sin(bdashrad) + Math.Cos(irad) * Math.Cos(bdashrad) * Math.Sin(ldashrad - omegarad), Math.Cos(bdashrad) * Math.Cos(ldashrad - omegarad))));
            details.U2     = AASCoordinateTransformation.MapTo0To360Range(AASCoordinateTransformation.RadiansToDegrees(Math.Atan2(Math.Sin(irad) * Math.Sin(beta) + Math.Cos(irad) * Math.Cos(beta) * Math.Sin(lambda - omegarad), Math.Cos(beta) * Math.Cos(lambda - omegarad))));
            details.DeltaU = Math.Abs(details.U1 - details.U2);
            if (details.DeltaU > 180)
            {
                details.DeltaU = 360 - details.DeltaU;
            }

            //Step 10. Calculate the Nutations
            double Obliquity           = AASNutation.TrueObliquityOfEcliptic(JD);
            double NutationInLongitude = AASNutation.NutationInLongitude(JD);

            //Step 11. Calculate the Ecliptical longitude and latitude of the northern pole of the ring plane
            double lambda0 = omega - 90;
            double beta0   = 90 - i;

            //Step 12. Correct lambda and beta for the aberration of Saturn
            lambda += AASCoordinateTransformation.DegreesToRadians(0.005693 * Math.Cos(l0rad - lambda) / Math.Cos(beta));
            beta   += AASCoordinateTransformation.DegreesToRadians(0.005693 * Math.Sin(l0rad - lambda) * Math.Sin(beta));

            //Step 13. Add nutation in longitude to lambda0 and lambda
            lambda   = AASCoordinateTransformation.RadiansToDegrees(lambda);
            lambda  += NutationInLongitude / 3600;
            lambda   = AASCoordinateTransformation.MapTo0To360Range(lambda);
            lambda0 += NutationInLongitude / 3600;
            lambda0  = AASCoordinateTransformation.MapTo0To360Range(lambda0);

            //Step 14. Convert to equatorial coordinates
            beta = AASCoordinateTransformation.RadiansToDegrees(beta);
            AAS2DCoordinate GeocentricEclipticSaturn = AASCoordinateTransformation.Ecliptic2Equatorial(lambda, beta, Obliquity);
            double          alpha = AASCoordinateTransformation.HoursToRadians(GeocentricEclipticSaturn.X);
            double          delta = AASCoordinateTransformation.DegreesToRadians(GeocentricEclipticSaturn.Y);
            AAS2DCoordinate GeocentricEclipticNorthPole = AASCoordinateTransformation.Ecliptic2Equatorial(lambda0, beta0, Obliquity);
            double          alpha0 = AASCoordinateTransformation.HoursToRadians(GeocentricEclipticNorthPole.X);
            double          delta0 = AASCoordinateTransformation.DegreesToRadians(GeocentricEclipticNorthPole.Y);

            //Step 15. Calculate the Position angle
            details.P = AASCoordinateTransformation.RadiansToDegrees(Math.Atan2(Math.Cos(delta0) * Math.Sin(alpha0 - alpha), Math.Sin(delta0) * Math.Cos(delta) - Math.Cos(delta0) * Math.Sin(delta) * Math.Cos(alpha0 - alpha)));

            return(details);
        }
Ejemplo n.º 12
0
        public static AASEllipticalPlanetaryDetails Calculate(double JD, AASEllipticalObject ellipticalObject, bool bHighPrecision)
        {
            //What will the the return value
            AASEllipticalPlanetaryDetails details = new AASEllipticalPlanetaryDetails();

            //Calculate the position of the earth first
            double JD0 = JD;
            double L0  = AASEarth.EclipticLongitude(JD0, bHighPrecision);
            double B0  = AASEarth.EclipticLatitude(JD0, bHighPrecision);
            double R0  = AASEarth.RadiusVector(JD0, bHighPrecision);

            L0 = AASCoordinateTransformation.DegreesToRadians(L0);
            B0 = AASCoordinateTransformation.DegreesToRadians(B0);
            double cosB0 = Math.Cos(B0);

            //Iterate to find the positions adjusting for light-time correction if required
            double L = 0;
            double B = 0;
            double R = 0;

            if (ellipticalObject != AASEllipticalObject.SUN)
            {
                bool   bRecalc      = true;
                bool   bFirstRecalc = true;
                double LPrevious    = 0;
                double BPrevious    = 0;
                double RPrevious    = 0;

                while (bRecalc)
                {
                    switch (ellipticalObject)
                    {
                    case AASEllipticalObject.SUN:

                        L = AASSun.GeometricEclipticLongitude(JD0, bHighPrecision);
                        B = AASSun.GeometricEclipticLatitude(JD0, bHighPrecision);
                        R = AASEarth.RadiusVector(JD0, bHighPrecision);
                        break;

                    case AASEllipticalObject.MERCURY:

                        L = AASMercury.EclipticLongitude(JD0, bHighPrecision);
                        B = AASMercury.EclipticLatitude(JD0, bHighPrecision);
                        R = AASMercury.RadiusVector(JD0, bHighPrecision);
                        break;

                    case AASEllipticalObject.VENUS:

                        L = AASVenus.EclipticLongitude(JD0, bHighPrecision);
                        B = AASVenus.EclipticLatitude(JD0, bHighPrecision);
                        R = AASVenus.RadiusVector(JD0, bHighPrecision);
                        break;

                    case AASEllipticalObject.MARS:

                        L = AASMars.EclipticLongitude(JD0, bHighPrecision);
                        B = AASMars.EclipticLatitude(JD0, bHighPrecision);
                        R = AASMars.RadiusVector(JD0, bHighPrecision);
                        break;

                    case AASEllipticalObject.JUPITER:

                        L = AASJupiter.EclipticLongitude(JD0, bHighPrecision);
                        B = AASJupiter.EclipticLatitude(JD0, bHighPrecision);
                        R = AASJupiter.RadiusVector(JD0, bHighPrecision);
                        break;

                    case AASEllipticalObject.SATURN:

                        L = AASSaturn.EclipticLongitude(JD0, bHighPrecision);
                        B = AASSaturn.EclipticLatitude(JD0, bHighPrecision);
                        R = AASSaturn.RadiusVector(JD0, bHighPrecision);
                        break;

                    case AASEllipticalObject.URANUS:

                        L = AASUranus.EclipticLongitude(JD0, bHighPrecision);
                        B = AASUranus.EclipticLatitude(JD0, bHighPrecision);
                        R = AASUranus.RadiusVector(JD0, bHighPrecision);
                        break;

                    case AASEllipticalObject.NEPTUNE:

                        L = AASNeptune.EclipticLongitude(JD0, bHighPrecision);
                        B = AASNeptune.EclipticLatitude(JD0, bHighPrecision);
                        R = AASNeptune.RadiusVector(JD0, bHighPrecision);
                        break;

                    case AASEllipticalObject.PLUTO:

                        L = AASPluto.EclipticLongitude(JD0);
                        B = AASPluto.EclipticLatitude(JD0);
                        R = AASPluto.RadiusVector(JD0);
                        break;

                    default:
                        break;
                    }

                    if (!bFirstRecalc)
                    {
                        bRecalc   = ((Math.Abs(L - LPrevious) > 0.00001) || (Math.Abs(B - BPrevious) > 0.00001) || (Math.Abs(R - RPrevious) > 0.000001));
                        LPrevious = L;
                        BPrevious = B;
                        RPrevious = R;
                    }
                    else
                    {
                        bFirstRecalc = false;
                    }

                    //Calculate the new value
                    if (bRecalc)
                    {
                        double Lrad     = AASCoordinateTransformation.DegreesToRadians(L);
                        double Brad     = AASCoordinateTransformation.DegreesToRadians(B);
                        double cosB     = Math.Cos(Brad);
                        double cosL     = Math.Cos(Lrad);
                        double x1       = R * cosB * cosL - R0 * cosB0 * Math.Cos(L0);
                        double y1       = R * cosB * Math.Sin(Lrad) - R0 * cosB0 * Math.Sin(L0);
                        double z1       = R * Math.Sin(Brad) - R0 * Math.Sin(B0);
                        double distance = Math.Sqrt(x1 * x1 + y1 * y1 + z1 * z1);

                        //Prepare for the next loop around
                        JD0 = JD - AASElliptical.DistanceToLightTime(distance);
                    }
                }
            }

            double x = 0;
            double y = 0;
            double z = 0;

            if (ellipticalObject != AASEllipticalObject.SUN)
            {
                double Lrad = AASCoordinateTransformation.DegreesToRadians(L);
                double Brad = AASCoordinateTransformation.DegreesToRadians(B);
                double cosB = Math.Cos(Brad);
                double cosL = Math.Cos(Lrad);

                x = R * cosB * cosL - R0 * cosB0 * Math.Cos(L0);
                y = R * cosB * Math.Sin(Lrad) - R0 * cosB0 * Math.Sin(L0);
                z = R * Math.Sin(Brad) - R0 * Math.Sin(B0);
            }
            else
            {
                x = -R0 *cosB0 *Math.Cos(L0);

                y = -R0 *cosB0 *Math.Sin(L0);

                z = -R0 *Math.Sin(B0);
            }

            double x2 = x * x;
            double y2 = y * y;

            details.ApparentGeocentricLatitude  = AASCoordinateTransformation.RadiansToDegrees(Math.Atan2(z, Math.Sqrt(x2 + y2)));
            details.ApparentGeocentricDistance  = Math.Sqrt(x2 + y2 + z * z);
            details.ApparentGeocentricLongitude = AASCoordinateTransformation.MapTo0To360Range(AASCoordinateTransformation.RadiansToDegrees(Math.Atan2(y, x)));
            details.ApparentLightTime           = AASElliptical.DistanceToLightTime(details.ApparentGeocentricDistance);

            //Adjust for Aberration
            AAS2DCoordinate Aberration = AASAberration.EclipticAberration(details.ApparentGeocentricLongitude, details.ApparentGeocentricLatitude, JD, bHighPrecision);

            details.ApparentGeocentricLongitude += Aberration.X;
            details.ApparentGeocentricLatitude  += Aberration.Y;

            //convert to the FK5 system
            double DeltaLong = AASFK5.CorrectionInLongitude(details.ApparentGeocentricLongitude, details.ApparentGeocentricLatitude, JD);

            details.ApparentGeocentricLatitude  += AASFK5.CorrectionInLatitude(details.ApparentGeocentricLongitude, JD);
            details.ApparentGeocentricLongitude += DeltaLong;

            //Correct for nutation
            double NutationInLongitude = AASNutation.NutationInLongitude(JD);
            double Epsilon             = AASNutation.TrueObliquityOfEcliptic(JD);

            details.ApparentGeocentricLongitude += AASCoordinateTransformation.DMSToDegrees(0, 0, NutationInLongitude);

            //Convert to RA and Dec
            AAS2DCoordinate ApparentEqu = AASCoordinateTransformation.Ecliptic2Equatorial(details.ApparentGeocentricLongitude, details.ApparentGeocentricLatitude, Epsilon);

            details.ApparentGeocentricRA          = ApparentEqu.X;
            details.ApparentGeocentricDeclination = ApparentEqu.Y;

            return(details);
        }
Ejemplo n.º 13
0
        public static CAAPhysicalJupiterDetails Calculate(double JD, bool bHighPrecision)
        {
            //What will be the return value
            CAAPhysicalJupiterDetails details = new CAAPhysicalJupiterDetails();

            //Step 1
            double d         = JD - 2433282.5;
            double T1        = d / 36525;
            double alpha0    = 268.00 + 0.1061 * T1;
            double alpha0rad = AASCoordinateTransformation.DegreesToRadians(alpha0);
            double delta0    = 64.50 - 0.0164 * T1;
            double delta0rad = AASCoordinateTransformation.DegreesToRadians(delta0);

            //Step 2
            double W1 = AASCoordinateTransformation.MapTo0To360Range(17.710 + 877.90003539 * d);
            double W2 = AASCoordinateTransformation.MapTo0To360Range(16.838 + 870.27003539 * d);

            //Step 3
            double l0    = AASEarth.EclipticLongitude(JD, bHighPrecision);
            double l0rad = AASCoordinateTransformation.DegreesToRadians(l0);
            double b0    = AASEarth.EclipticLatitude(JD, bHighPrecision);
            double b0rad = AASCoordinateTransformation.DegreesToRadians(b0);
            double R     = AASEarth.RadiusVector(JD, bHighPrecision);

            //Step 4
            double l    = AASJupiter.EclipticLongitude(JD, bHighPrecision);
            double lrad = AASCoordinateTransformation.DegreesToRadians(l);
            double b    = AASJupiter.EclipticLatitude(JD, bHighPrecision);
            double brad = AASCoordinateTransformation.DegreesToRadians(b);
            double r    = AASJupiter.RadiusVector(JD, bHighPrecision);

            //Step 5
            double x     = r * Math.Cos(brad) * Math.Cos(lrad) - R * Math.Cos(l0rad);
            double y     = r * Math.Cos(brad) * Math.Sin(lrad) - R * Math.Sin(l0rad);
            double z     = r * Math.Sin(brad) - R * Math.Sin(b0rad);
            double DELTA = Math.Sqrt(x * x + y * y + z * z);

            //Step 6
            l   -= 0.012990 * DELTA / (r * r);
            lrad = AASCoordinateTransformation.DegreesToRadians(l);

            //Step 7
            x     = r * Math.Cos(brad) * Math.Cos(lrad) - R * Math.Cos(l0rad);
            y     = r * Math.Cos(brad) * Math.Sin(lrad) - R * Math.Sin(l0rad);
            z     = r * Math.Sin(brad) - R * Math.Sin(b0rad);
            DELTA = Math.Sqrt(x * x + y * y + z * z);

            //Step 8
            double e0    = AASNutation.MeanObliquityOfEcliptic(JD);
            double e0rad = AASCoordinateTransformation.DegreesToRadians(e0);

            //Step 9
            double alphas = Math.Atan2(Math.Cos(e0rad) * Math.Sin(lrad) - Math.Sin(e0rad) * Math.Tan(brad), Math.Cos(lrad));
            double deltas = Math.Asin(Math.Cos(e0rad) * Math.Sin(brad) + Math.Sin(e0rad) * Math.Cos(brad) * Math.Sin(lrad));

            //Step 10
            details.DS = AASCoordinateTransformation.RadiansToDegrees(Math.Asin(-Math.Sin(delta0rad) * Math.Sin(deltas) - Math.Cos(delta0rad) * Math.Cos(deltas) * Math.Cos(alpha0rad - alphas)));

            //Step 11
            double u        = y * Math.Cos(e0rad) - z * Math.Sin(e0rad);
            double v        = y * Math.Sin(e0rad) + z * Math.Cos(e0rad);
            double alpharad = Math.Atan2(u, x);
            double alpha    = AASCoordinateTransformation.RadiansToDegrees(alpharad);
            double deltarad = Math.Atan2(v, Math.Sqrt(x * x + u * u));
            double delta    = AASCoordinateTransformation.RadiansToDegrees(deltarad);
            double xi       = Math.Atan2(Math.Sin(delta0rad) * Math.Cos(deltarad) * Math.Cos(alpha0rad - alpharad) - Math.Sin(deltarad) * Math.Cos(delta0rad), Math.Cos(deltarad) * Math.Sin(alpha0rad - alpharad));

            //Step 12
            details.DE = AASCoordinateTransformation.RadiansToDegrees(Math.Asin(-Math.Sin(delta0rad) * Math.Sin(deltarad) - Math.Cos(delta0rad) * Math.Cos(deltarad) * Math.Cos(alpha0rad - alpharad)));

            //Step 13
            details.Geometricw1 = AASCoordinateTransformation.MapTo0To360Range(W1 - AASCoordinateTransformation.RadiansToDegrees(xi) - 5.07033 * DELTA);
            details.Geometricw2 = AASCoordinateTransformation.MapTo0To360Range(W2 - AASCoordinateTransformation.RadiansToDegrees(xi) - 5.02626 * DELTA);

            //Step 14
            double C = 57.2958 * (2 * r * DELTA + R * R - r * r - DELTA * DELTA) / (4 * r * DELTA);

            if (Math.Sin(lrad - l0rad) > 0)
            {
                details.Apparentw1 = AASCoordinateTransformation.MapTo0To360Range(details.Geometricw1 + C);
                details.Apparentw2 = AASCoordinateTransformation.MapTo0To360Range(details.Geometricw2 + C);
            }
            else
            {
                details.Apparentw1 = AASCoordinateTransformation.MapTo0To360Range(details.Geometricw1 - C);
                details.Apparentw2 = AASCoordinateTransformation.MapTo0To360Range(details.Geometricw2 - C);
            }

            //Step 15
            double NutationInLongitude = AASNutation.NutationInLongitude(JD);
            double NutationInObliquity = AASNutation.NutationInObliquity(JD);

            e0   += NutationInObliquity / 3600;
            e0rad = AASCoordinateTransformation.DegreesToRadians(e0);

            //Step 16
            alpha   += 0.005693 * (Math.Cos(alpharad) * Math.Cos(l0rad) * Math.Cos(e0rad) + Math.Sin(alpharad) * Math.Sin(l0rad)) / Math.Cos(deltarad);
            alpha    = AASCoordinateTransformation.MapTo0To360Range(alpha);
            alpharad = AASCoordinateTransformation.DegreesToRadians(alpha);
            delta   += 0.005693 * (Math.Cos(l0rad) * Math.Cos(e0rad) * (Math.Tan(e0rad) * Math.Cos(deltarad) - Math.Sin(alpharad) * Math.Sin(deltarad)) + Math.Cos(alpharad) * Math.Sin(deltarad) * Math.Sin(l0rad));

            //Step 17
            double NutationRA   = AASNutation.NutationInRightAscension(alpha / 15, delta, e0, NutationInLongitude, NutationInObliquity);
            double alphadash    = alpha + NutationRA / 3600;
            double alphadashrad = AASCoordinateTransformation.DegreesToRadians(alphadash);
            double NutationDec  = AASNutation.NutationInDeclination(alpha / 15, e0, NutationInLongitude, NutationInObliquity);
            double deltadash    = delta + NutationDec / 3600;
            double deltadashrad = AASCoordinateTransformation.DegreesToRadians(deltadash);

            NutationRA = AASNutation.NutationInRightAscension(alpha0 / 15, delta0, e0, NutationInLongitude, NutationInObliquity);
            double alpha0dash    = alpha0 + NutationRA / 3600;
            double alpha0dashrad = AASCoordinateTransformation.DegreesToRadians(alpha0dash);

            NutationDec = AASNutation.NutationInDeclination(alpha0 / 15, e0, NutationInLongitude, NutationInObliquity);
            double delta0dash    = delta0 + NutationDec / 3600;
            double delta0dashrad = AASCoordinateTransformation.DegreesToRadians(delta0dash);

            //Step 18
            details.P = AASCoordinateTransformation.MapTo0To360Range(AASCoordinateTransformation.RadiansToDegrees(Math.Atan2(Math.Cos(delta0dashrad) * Math.Sin(alpha0dashrad - alphadashrad), Math.Sin(delta0dashrad) * Math.Cos(deltadashrad) - Math.Cos(delta0dashrad) * Math.Sin(deltadashrad) * Math.Cos(alpha0dashrad - alphadashrad))));

            return(details);
        }