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 static GCHourTime CalcSunrise(GregorianDateTime vct, GCEarthData earth)
{
double tempSunrise = 180.0;
GCSunData sun = new GCSunData();
for (int i = 0; i < 3; i++)
{
sun.SunPosition(vct, earth, tempSunrise - 180.0);
double x;
// definition of event
double eventdef = 0.01454;
/* switch(ed.obs)
* {
* case 1: // civil twilight
* eventdef = 0.10453;
* break;
* case 2: // nautical twilight
* eventdef = 0.20791;
* break;
* case 3: // astronomical twilight
* eventdef = 0.30902;
* break;
* default:// center of the sun on the horizont
* eventdef = 0.01454;
* break;
* }*/
eventdef = (eventdef / GCMath.cosDeg(earth.latitudeDeg)) / GCMath.cosDeg(sun.declinationDeg);
x = GCMath.tanDeg(earth.latitudeDeg) * GCMath.tanDeg(sun.declinationDeg) + eventdef;
if ((x >= -1.0) && (x <= 1.0))
{
// time of sunrise
tempSunrise = 90.0 - earth.longitudeDeg - GCMath.arcSinDeg(x) + sun.equationOfTime;
}
else
{
// initial values for the case
// that no rise no set for that day
tempSunrise = -360.0;
break;
}
}
GCHourTime result = new GCHourTime();
result.longitude = sun.longitudeDeg;
result.SetDegTime(tempSunrise + earth.OffsetUtcHours * 15.0);
return(result);
}
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 static GCHourTime CalcSunset(GregorianDateTime vct, GCEarthData earth)
{
double tempSunset = 180.0;
GCSunData sun = new GCSunData();
for (int i = 0; i < 3; i++)
{
sun.SunPosition(vct, earth, tempSunset - 180.0);
double x;
// definition of event
double eventdef = GCSunData.RiseAngleLevel;
eventdef = (eventdef / GCMath.cosDeg(earth.latitudeDeg)) / GCMath.cosDeg(sun.declinationDeg);
x = GCMath.tanDeg(earth.latitudeDeg) * GCMath.tanDeg(sun.declinationDeg) + eventdef;
if ((x >= -1.0) && (x <= 1.0))
{
// time of sunset
tempSunset = 270.0 - earth.longitudeDeg + GCMath.arcSinDeg(x) + sun.equationOfTime;
}
else
{
// initial values for the case
// that no rise no set for that day
tempSunset = -360.0;
break;
}
}
GCHourTime result = new GCHourTime();
result.longitude = sun.longitudeDeg;
result.SetDegTime(tempSunset + earth.OffsetUtcHours * 15.0);
return(result);
}
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));
}
// 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);
}
