public GCEquatorialCoords getTopocentricEquatorial(GCEarthData obs, double jdate)
{
double u, h, delta_alpha;
double rho_sin, rho_cos;
const double b_a = 0.99664719;
GCEquatorialCoords tec = new GCEquatorialCoords();
double altitude = 0;
// geocentric position of observer on the earth surface
// 10.1 - 10.3
u = GCMath.arcTanDeg(b_a * b_a * GCMath.tanDeg(obs.latitudeDeg));
rho_sin = b_a * GCMath.sinDeg(u) + altitude / 6378140.0 * GCMath.sinDeg(obs.latitudeDeg);
rho_cos = GCMath.cosDeg(u) + altitude / 6378140.0 * GCMath.cosDeg(obs.latitudeDeg);
// equatorial horizontal paralax
// 39.1
double parallax = GCMath.arcSinDeg(GCMath.sinDeg(8.794 / 3600) / (radius / GCMath.AU));
// geocentric hour angle of the body
h = GCEarthData.SiderealTimeGreenwich(jdate) + obs.longitudeDeg - rightAscension;
// 39.2
delta_alpha = GCMath.arcTanDeg(
(-rho_cos * GCMath.sinDeg(parallax) * GCMath.sinDeg(h)) /
(GCMath.cosDeg(this.declination) - rho_cos * GCMath.sinDeg(parallax) * GCMath.cosDeg(h)));
tec.rightAscension = rightAscension + delta_alpha;
tec.declination = declination + GCMath.arcTanDeg(
((GCMath.sinDeg(declination) - rho_sin * GCMath.sinDeg(parallax)) * GCMath.cosDeg(delta_alpha)) /
(GCMath.cosDeg(declination) - rho_cos * GCMath.sinDeg(parallax) * GCMath.cosDeg(h)));
return(tec);
}
//==================================================================================
//
//==================================================================================
public void calc_horizontal(double date, double longitude, double latitude)
{
double h;
h = GCMath.putIn360(GCEarthData.SiderealTimeGreenwich(date) - this.rightAscension + longitude);
this.azimuth = GCMath.rad2deg(Math.Atan2(GCMath.sinDeg(h),
GCMath.cosDeg(h) * GCMath.sinDeg(latitude) -
GCMath.tanDeg(this.declination) * GCMath.cosDeg(latitude)));
this.elevation = GCMath.rad2deg(Math.Asin(GCMath.sinDeg(latitude) * GCMath.sinDeg(this.declination) +
GCMath.cosDeg(latitude) * GCMath.cosDeg(this.declination) * GCMath.cosDeg(h)));
}
/// <summary>
///
/// </summary>
/// <param name="julianDateUTC">This contains time UTC, that means time observed on Greenwich meridian. DateTime in other
/// timezones should be converted into timezone UTC+0h before using in this method.</param>
/// <returns></returns>
public double GetAscendantDegrees(double julianDateUTC)
{
double A = GCEarthData.SiderealTimeLocal(julianDateUTC, longitudeDeg, OffsetUtcHours * 15.0);
double E = 23.4392911;
double ascendant = GCMath.arcTan2Deg(-GCMath.cosDeg(A), GCMath.sinDeg(A) * GCMath.cosDeg(E) + GCMath.tanDeg(latitudeDeg) * GCMath.sinDeg(E));
if (ascendant < 180)
{
ascendant += 180;
}
else
{
ascendant -= 180;
}
return(GCMath.putIn360(ascendant - GCAyanamsha.GetAyanamsa(julianDateUTC)));
}
public static GCHorizontalCoords equatorialToHorizontalCoords(GCEquatorialCoords eqc, GCEarthData obs, double date)
{
double localHourAngle;
GCHorizontalCoords hc;
localHourAngle = GCMath.putIn360(GCEarthData.SiderealTimeGreenwich(date) - eqc.rightAscension + obs.longitudeDeg);
hc.azimut = GCMath.rad2deg(Math.Atan2(GCMath.sinDeg(localHourAngle),
GCMath.cosDeg(localHourAngle) * GCMath.sinDeg(obs.latitudeDeg) -
GCMath.tanDeg(eqc.declination) * GCMath.cosDeg(obs.latitudeDeg)));
hc.elevation = GCMath.rad2deg(Math.Asin(GCMath.sinDeg(obs.latitudeDeg) * GCMath.sinDeg(eqc.declination) +
GCMath.cosDeg(obs.latitudeDeg) * GCMath.cosDeg(eqc.declination) * GCMath.cosDeg(localHourAngle)));
return(hc);
}
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);
}
public void CorrectEqatorialWithParallax(double jdate, double latitude, double longitude, double height)
{
double u, hourAngleBody, delta_alpha;
double rho_sin, rho_cos;
const double b_a = 0.99664719;
// calculate geocentric longitude and latitude of observer
u = GCMath.arcTanDeg(b_a * b_a * GCMath.tanDeg(latitude));
rho_sin = b_a * GCMath.sinDeg(u) + height / 6378140.0 * GCMath.sinDeg(latitude);
rho_cos = GCMath.cosDeg(u) + height / 6378140.0 * GCMath.cosDeg(latitude);
// calculate paralax
this.parallax = GCMath.arcSinDeg(GCMath.sinDeg(8.794 / 3600) / (MoonDistance(jdate) / GCMath.AU));
// calculate correction of equatorial coordinates
hourAngleBody = GCEarthData.SiderealTimeGreenwich(jdate) + longitude - this.rightAscension;
delta_alpha = GCMath.arcTan2Deg(-rho_cos * GCMath.sinDeg(this.parallax) * GCMath.sinDeg(hourAngleBody),
GCMath.cosDeg(this.declination) - rho_cos * GCMath.sinDeg(this.parallax) * GCMath.cosDeg(hourAngleBody));
this.rightAscension += delta_alpha;
this.declination += GCMath.arcTan2Deg(
(GCMath.sinDeg(this.declination) - rho_sin * GCMath.sinDeg(this.parallax)) * GCMath.cosDeg(delta_alpha),
GCMath.cosDeg(this.declination) - rho_cos * GCMath.sinDeg(this.parallax) * GCMath.cosDeg(hourAngleBody));
}
public static GCEclipticalCoords CalculateEcliptical(double jdate)
{
double t, d, m, ms, f, e, ls;
double sr, sl, sb, temp; // : extended;
double a1, a2, a3; // : extended;
int i; //: integer;
t = (jdate - 2451545.0) / 36525.0;
//(* mean elongation of the moon
d = 297.8502042 + (445267.1115168 + (-0.0016300 + (1.0 / 545868 - 1.0 / 113065000 * t) * t) * t) * t;
//(* mean anomaly of the sun
m = 357.5291092 + (35999.0502909 + (-0.0001536 + 1.0 / 24490000 * t) * t) * t;
//(* mean anomaly of the moon
ms = 134.9634114 + (477198.8676313 + (0.0089970 + (1.0 / 69699 - 1.0 / 1471200 * t) * t) * t) * t;
//(* argument of the longitude of the moon
f = 93.2720993 + (483202.0175273 + (-0.0034029 + (-1.0 / 3526000 + 1.0 / 863310000 * t) * t) * t) * t;
//(* correction term due to excentricity of the earth orbit
e = 1.0 + (-0.002516 - 0.0000074 * t) * t;
//(* mean longitude of the moon
ls = 218.3164591 + (481267.88134236 + (-0.0013268 + (1.0 / 538841 - 1.0 / 65194000 * t) * t) * t) * t;
//(* arguments of correction terms
a1 = 119.75 + 131.849 * t;
a2 = 53.09 + 479264.290 * t;
a3 = 313.45 + 481266.484 * t;
sr = 0;
for (i = 0; i < 60; i++)
{
temp = sigma_r[i] * GCMath.cosDeg(arg_lr[i, 0] * d
+ arg_lr[i, 1] * m
+ arg_lr[i, 2] * ms
+ arg_lr[i, 3] * f);
if (Math.Abs(arg_lr[i, 1]) == 1)
{
temp = temp * e;
}
if (Math.Abs(arg_lr[i, 1]) == 2)
{
temp = temp * e * e;
}
sr = sr + temp;
}
sl = 0;
for (i = 0; i < 60; i++)
{
temp = sigma_l[i] * GCMath.sinDeg(arg_lr[i, 0] * d
+ arg_lr[i, 1] * m
+ arg_lr[i, 2] * ms
+ arg_lr[i, 3] * f);
if (Math.Abs(arg_lr[i, 1]) == 1)
{
temp = temp * e;
}
if (Math.Abs(arg_lr[i, 1]) == 2)
{
temp = temp * e * e;
}
sl = sl + temp;
}
//(* correction terms
sl = sl + 3958 * GCMath.sinDeg(a1)
+ 1962 * GCMath.sinDeg(ls - f)
+ 318 * GCMath.sinDeg(a2);
sb = 0;
for (i = 0; i < 60; i++)
{
temp = sigma_b[i] * GCMath.sinDeg(arg_b[i, 0] * d
+ arg_b[i, 1] * m
+ arg_b[i, 2] * ms
+ arg_b[i, 3] * f);
if (Math.Abs(arg_b[i, 1]) == 1)
{
temp = temp * e;
}
if (Math.Abs(arg_b[i, 1]) == 2)
{
temp = temp * e * e;
}
sb = sb + temp;
}
//(* correction terms
sb = sb - 2235 * GCMath.sinDeg(ls)
+ 382 * GCMath.sinDeg(a3)
+ 175 * GCMath.sinDeg(a1 - f)
+ 175 * GCMath.sinDeg(a1 + f)
+ 127 * GCMath.sinDeg(ls - ms)
- 115 * GCMath.sinDeg(ls + ms);
GCEclipticalCoords coords;
coords.longitude = ls + sl / 1000000;
coords.latitude = sb / 1000000;
coords.distance = 385000.56 + sr / 1000;
return(coords);
}
/// <summary>
/// This is implementation from Chapter 21, Astronomical Algorithms
/// Nutation of longitude and Obliquity of ecliptic
/// </summary>
/// <param name="julianDateUTC"></param>
/// <param name="nutationLongitude"></param>
/// <param name="obliquity"></param>
public static void CalculateNutations(double julianDateUTC, out double nutationLongitude, out double obliquity)
{
double t, omega;
double d, m, ms, f, s, l, ls;
int i;
double meanObliquity, nutationObliquity;
t = (julianDateUTC - 2451545.0) / 36525;
// longitude of rising knot
omega = GCMath.putIn360(125.04452 + (-1934.136261 + (0.0020708 + 1.0 / 450000 * t) * t) * t);
if (LowPrecisionNutations)
{
// (*@/// delta_phi and delta_epsilon - low accuracy *)
//(* mean longitude of sun (l) and moon (ls) *)
l = 280.4665 + 36000.7698 * t;
ls = 218.3165 + 481267.8813 * t;
//(* correction due to nutation *)
nutationObliquity = 9.20 * GCMath.cosDeg(omega) + 0.57 * GCMath.cosDeg(2 * l) + 0.10 * GCMath.cosDeg(2 * ls) - 0.09 * GCMath.cosDeg(2 * omega);
//(* longitude correction due to nutation *)
nutationLongitude = (-17.20 * GCMath.sinDeg(omega) - 1.32 * GCMath.sinDeg(2 * l) - 0.23 * GCMath.sinDeg(2 * ls) + 0.21 * GCMath.sinDeg(2 * omega)) / 3600;
}
else
{
// mean elongation of moon to sun
d = GCMath.putIn360(297.85036 + (445267.111480 + (-0.0019142 + t / 189474) * t) * t);
// mean anomaly of the sun
m = GCMath.putIn360(357.52772 + (35999.050340 + (-0.0001603 - t / 300000) * t) * t);
// mean anomaly of the moon
ms = GCMath.putIn360(134.96298 + (477198.867398 + (0.0086972 + t / 56250) * t) * t);
// argument of the latitude of the moon
f = GCMath.putIn360(93.27191 + (483202.017538 + (-0.0036825 + t / 327270) * t) * t);
nutationLongitude = 0;
nutationObliquity = 0;
for (i = 0; i < 31; i++)
{
s = arg_mul[i, 0] * d
+ arg_mul[i, 1] * m
+ arg_mul[i, 2] * ms
+ arg_mul[i, 3] * f
+ arg_mul[i, 4] * omega;
nutationLongitude = nutationLongitude + (arg_phi[i, 0] + arg_phi[i, 1] * t * 0.1) * GCMath.sinDeg(s);
nutationObliquity = nutationObliquity + (arg_eps[i, 0] + arg_eps[i, 1] * t * 0.1) * GCMath.cosDeg(s);
}
nutationLongitude = nutationLongitude * 0.0001 / 3600;
nutationObliquity = nutationObliquity * 0.0001;
}
// angle of ecliptic
meanObliquity = 84381.448 + (-46.8150 + (-0.00059 + 0.001813 * t) * t) * t;
obliquity = (meanObliquity + nutationObliquity) / 3600;
}
// this is not used effectovely
// it is just try to have some alternative function for calculation sun position
// but it needs to be fixed, because
// it calculates correct ecliptical coordinates, but when transforming
// into horizontal coordinates (azimut, elevation) it will do something wrong
public static GCHorizontalCoords sunPosition(int year, int month, int day, int hour, int min, int sec,
double lat, double longi)
{
double twopi = GCMath.PI2;
double deg2rad = GCMath.PI2 / 180;
int[] month_days = { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30 };
for (int y2 = 0; y2 < month; y2++)
{
day += month_days[y2];
}
if ((year % 4 == 0) && ((year % 400 == 0) || (year % 100 != 0)) && (day >= 60) && !(month == 2 & day == 60))
{
day++;
}
//# Get Julian date - 2400000
double hourd = hour + min / 60.0 + sec / 3600.0; // hour plus fraction
double delta = year - 1949;
double leap = Math.Floor(delta / 4); // former leapyears
double jd = 32916.5 + delta * 365 + leap + day + hourd / 24.0;
// The input to the Atronomer's almanach is the difference between
// the Julian date and JD 2451545.0 (noon, 1 January 2000)
double time = jd - 51545.0;
// Ecliptic coordinates
// Mean longitude
double mnlong = GCMath.putIn360(280.460 + .9856474 * time);
// Mean anomaly
double mnanom = GCMath.putIn360(357.528 + .9856003 * time);
//mnanom <- mnanom * deg2rad
// Ecliptic longitude and obliquity of ecliptic
double eclong = mnlong + 1.915 * GCMath.sinDeg(mnanom) + 0.020 * GCMath.sinDeg(2 * mnanom);
eclong = GCMath.putIn360(eclong);
double oblqec = 23.439 - 0.0000004 * time;
//-- eclong <- eclong * deg2rad
//-- oblqec <- oblqec * deg2rad
// Celestial coordinates
// Right ascension and declination
double num = GCMath.cosDeg(oblqec) * GCMath.sinDeg(eclong);
double den = GCMath.cosDeg(eclong);
double ra = GCMath.arcTan2Deg(num, den);
while (ra < 0)
{
ra += 180;
}
//-- ra[den < 0] <- ra[den < 0] + pi
if (den >= 0 && num < 0)
{
ra += 360;
}
double dec = GCMath.arcSinDeg(GCMath.sinDeg(oblqec) * GCMath.sinDeg(eclong));
// Local coordinates
// Greenwich mean sidereal time
double gmst = 6.697375 + .0657098242 * time + hourd;
gmst = GCMath.putIn24(gmst);
// Local mean sidereal time
double lmst = gmst + longi / 15.0;
lmst = GCMath.putIn24(lmst);
lmst = lmst * 15.0;
// Hour angle
double ha = lmst - ra;
ha = GCMath.putIn180(ha);
// Azimuth and elevation
double el = GCMath.arcSinDeg(GCMath.sinDeg(dec) * GCMath.sinDeg(lat) + GCMath.cosDeg(dec) * GCMath.cosDeg(lat) * GCMath.cosDeg(ha));
double az = GCMath.arcSinDeg(-GCMath.cosDeg(dec) * GCMath.sinDeg(ha) / GCMath.cosDeg(el));
//# -----------------------------------------------
//# New code
//# Solar zenith angle
double zenithAngle = GCMath.arccosDeg(GCMath.sinDeg(lat) * GCMath.sinDeg(dec) + GCMath.cosDeg(lat) * GCMath.cosDeg(dec) * GCMath.cosDeg(ha));
//# Solar azimuth
az = GCMath.arccosDeg(((GCMath.sinDeg(lat) * GCMath.cosDeg(zenithAngle)) - GCMath.sinDeg(dec)) / (GCMath.cosDeg(lat) * GCMath.sinDeg(zenithAngle)));
//# -----------------------------------------------
//# Azimuth and elevation
el = GCMath.arcSinDeg(GCMath.sinDeg(dec) * GCMath.sinDeg(lat) + GCMath.cosDeg(dec) * GCMath.cosDeg(lat) * GCMath.cosDeg(ha));
//# -----------------------------------------------
//# New code
if (ha > 0)
{
az += 180;
}
else
{
az = 540 - az;
}
az = GCMath.putIn360(az);
// For logic and names, see Spencer, J.W. 1989. Solar Energy. 42(4):353
//cosAzPos <- (0 <= sin(dec) - sin(el) * sin(lat))
//sinAzNeg <- (sin(az) < 0)
//az[cosAzPos & sinAzNeg] <- az[cosAzPos & sinAzNeg] + twopi
//az[!cosAzPos] <- pi - az[!cosAzPos]
/*
* if (0 < GCMath.sinDeg(dec) - GCMath.sinDeg(el) * GCMath.sinDeg(lat))
* {
* if(GCMath.sinDeg(az) < 0)
* {
* az = az + 360;
* }
* }
* else
* {
* az = 180 - az;
* }
*/
//el <- el / deg2rad
//az <- az / deg2rad
//lat <- lat / deg2rad
GCHorizontalCoords coords;
coords.azimut = az;
coords.elevation = el;
return(coords);
}
