public static AAS2DCoordinate MoonPosition(DateTime dateTime)
{
dateTime = dateTime.ToUniversalTime(); // NOTE: time must be converted to Universal Time
//Calculate the topocentric horizontal position of the Moon
AASDate dateMoonCalc = new AASDate(dateTime.Year, dateTime.Month, dateTime.Day, dateTime.Hour, dateTime.Minute, dateTime.Second, true);
double JDMoon = dateMoonCalc.Julian + AASDynamicalTime.DeltaT(dateMoonCalc.Julian) / 86400.0;
double MoonLong = AASMoon.EclipticLongitude(JDMoon);
double MoonLat = AASMoon.EclipticLatitude(JDMoon);
AAS2DCoordinate Equatorial = AASCoordinateTransformation.Ecliptic2Equatorial(MoonLong, MoonLat, AASNutation.TrueObliquityOfEcliptic(JDMoon));
double MoonRad = AASMoon.RadiusVector(JDMoon);
MoonRad /= 149597870.691; //Convert KM to AU
AAS2DCoordinate MoonTopo = AASParallax.Equatorial2Topocentric(Equatorial.X, Equatorial.Y, MoonRad, RT_LONG, RT_LAT, RT_HEIGHT, JDMoon);
double AST = AASSidereal.ApparentGreenwichSiderealTime(dateMoonCalc.Julian);
double LongtitudeAsHourAngle = AASCoordinateTransformation.DegreesToHours(RT_LONG);
double LocalHourAngle = AST - LongtitudeAsHourAngle - MoonTopo.X;
AAS2DCoordinate MoonHorizontal = AASCoordinateTransformation.Equatorial2Horizontal(LocalHourAngle, MoonTopo.Y, RT_LAT);
MoonHorizontal.Y += AASRefraction.RefractionFromTrue(MoonHorizontal.Y, 1013, 10);
//The result above should be that we have a rising Moon at Y degrees above the horizon at azimuth X degrees east of the southern horizon
//NOTE: for azimuth west is considered positive, to get east as positive subtract the result from 360
return(MoonHorizontal);
}
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
//----------------------------------------- COORDINATE_TRANSFORMATION ---------------------------------------------
/*
* This script does the following:
* - Transform from horizontal to celestial coordinates
*
*
* */
// returns the sidereal time at the designated longitude
public static float LocalSiderealTime(float lng)
{
// get the current time
DateTime now = DateTime.Now;
//create time custom time object
AASDate dateSunCalc = new AASDate(now.Year, now.Month, now.Day, now.Hour, now.Minute, now.Second, true);
//get greenwich time
double greenwich_sidereal_time = AASSidereal.MeanGreenwichSiderealTime(dateSunCalc.Julian);
//adjust for longitude
double adj_st = greenwich_sidereal_time + (lng * (24.0 / 360.0));
if (adj_st >= 24.0)
{
adj_st -= 24.0;
}
if (adj_st < 0)
{
adj_st += 24.0;
}
return((float)adj_st);
}
public static AAS2DCoordinate SunPosition(DateTime dateTime)
{
var bHighPrecision = false;
dateTime = dateTime.ToUniversalTime(); // NOTE: time must be converted to Universal Time
//Calculate the topocentric horizontal position of the Sun
AASDate dateSunCalc = new AASDate(dateTime.Year, dateTime.Month, dateTime.Day, dateTime.Hour, dateTime.Minute, dateTime.Second, true);
double JDSun = dateSunCalc.Julian + AASDynamicalTime.DeltaT(dateSunCalc.Julian) / 86400.0;
double SunLong = AASSun.ApparentEclipticLongitude(JDSun, bHighPrecision);
double SunLat = AASSun.ApparentEclipticLatitude(JDSun, bHighPrecision);
AAS2DCoordinate Equatorial = AASCoordinateTransformation.Ecliptic2Equatorial(SunLong, SunLat, AASNutation.TrueObliquityOfEcliptic(JDSun));
double SunRad = AASEarth.RadiusVector(JDSun, bHighPrecision);
AAS2DCoordinate SunTopo = AASParallax.Equatorial2Topocentric(Equatorial.X, Equatorial.Y, SunRad, RT_LONG, RT_LAT, RT_HEIGHT, JDSun);
double AST = AASSidereal.ApparentGreenwichSiderealTime(dateSunCalc.Julian);
double LongtitudeAsHourAngle = AASCoordinateTransformation.DegreesToHours(RT_LONG);
double LocalHourAngle = AST - LongtitudeAsHourAngle - SunTopo.X;
AAS2DCoordinate SunHorizontal = AASCoordinateTransformation.Equatorial2Horizontal(LocalHourAngle, SunTopo.Y, RT_LAT);
SunHorizontal.Y += AASRefraction.RefractionFromTrue(SunHorizontal.Y, 1013, 10);
//The result above should be that we have a setting Sun at Y degrees above the horizon at azimuth X degrees south of the westerly horizon
//NOTE: for azimuth west is considered positive, to get east as positive subtract the result from 360
return(SunHorizontal);
}
public Coordinate OrientationToCoordinate(Orientation currHorizontal, DateTime datetime)
{
// We don't want to modify the current orientation, so we must create a new instance
Orientation horizontal = (Orientation)currHorizontal.Clone();
if (horizontal == null)
{
throw new ArgumentException("Orientation cannot be null");
}
// Since AASharp considers south zero, flip the orientation 180 degrees
horizontal.Azimuth += 180;
if (horizontal.Azimuth > 360)
{
horizontal.Azimuth -= 360;
}
AAS2DCoordinate equatorial = AASCoordinateTransformation.Horizontal2Equatorial(horizontal.Azimuth, horizontal.Elevation, Location.Latitude);
AASDate date = new AASDate(datetime.Year, datetime.Month, datetime.Day, datetime.Hour, datetime.Minute, datetime.Second, true);
double ApparentGreenwichSiderealTime = AASSidereal.ApparentGreenwichSiderealTime(date.Julian);
double LongtitudeAsHourAngle = AASCoordinateTransformation.DegreesToHours(Location.Longitude);
double RightAscension = ApparentGreenwichSiderealTime - LongtitudeAsHourAngle - equatorial.X;
if (RightAscension < 0)
{
RightAscension += 24;
}
return(new Coordinate(RightAscension, equatorial.Y));
}
//hour angle of the aries point
public double GetHourAngleOfAriesPoint(){
double theta0Apparent = AASSidereal.ApparentGreenwichSiderealTime (jd);
//hour angle in hours
double H = theta0Apparent - location.longitude/15d;
return H;
}
public EquatorialCoords Horizontal2Equatorial(double azimuth, double altitude){
AAS2DCoordinate coords = AASCoordinateTransformation.Horizontal2Equatorial (azimuth+180, altitude, location.latitude);
//right ascension (alpha) = apparent sidereal time at Greenwich (theta) - Local hour angle (H) - observer's longitude (L, positive west, negative east from Greenwich)
double theta0Apparent = AASSidereal.ApparentGreenwichSiderealTime (jd);
double ra = theta0Apparent - coords.X - location.longitude / 15d;
return new EquatorialCoords(new HourAngle(ra), new DegreesAngle( coords.Y ));
}
public void MeanGreenwichSiderealTimeTest(int year, int month, int day, int hours, int minutes, int seconds, bool isGregorian, double expectedSideralTime)
{
var date = new AASDate();
date.Set(year, month, day, hours, minutes, seconds, isGregorian);
double meanGreenwichSiderealTime = AASSidereal.MeanGreenwichSiderealTime(date.Julian);
Assert.Equal(expectedSideralTime, meanGreenwichSiderealTime);
}
public LocalCoords Equatorial2Horizontal(double ra, double dec){
double theta0Apparent = AASSidereal.ApparentGreenwichSiderealTime (jd);
//hour angle in hours
double H = theta0Apparent - location.longitude/15d - ra;
AAS2DCoordinate localCoords = AASCoordinateTransformation.Equatorial2Horizontal (H, dec, location.latitude);
double azimuth = AASCoordinateTransformation.MapTo0To360Range (localCoords.X + 180d);
return new LocalCoords(new DegreesAngle(azimuth), new DegreesAngle(localCoords.Y));
}
protected void CalculateTopocentricPosition()
{
double theta0Apparent = AASSidereal.ApparentGreenwichSiderealTime(jd);
//hour angle in hours
localHourAngle = theta0Apparent - location.longitude / 15d - equatorialCoords.RA.Get();
AAS2DCoordinate local = AASCoordinateTransformation.Equatorial2Horizontal(localHourAngle, equatorialCoords.Declination.Get(), location.latitude);
localCoords.Azimuth = DegreesAngle.FromDecimalTo0To360Range(180.0f + local.X);
localCoords.Altitude = new DegreesAngle(local.Y);
}
/*
* public LocalCoords LocalCoords(double jd, LocationData location){
* double theta0Apparent = AASSidereal.ApparentGreenwichSiderealTime (jd);
*
* //hour angle in hours
* double H = theta0Apparent - location.longitude/15d - ra;
*
* AAS2DCoordinate localCoords = AASCoordinateTransformation.Equatorial2Horizontal (H, dec, location.latitude);
* double azimuth = AASCoordinateTransformation.MapTo0To360Range (localCoords.X + 180d);
*
* return new LocalCoords(new DegreesAngle(azimuth), new DegreesAngle(localCoords.Y));
* }*/
public Vector3 GetLocalRectangularCoordinates(double jd, LocationData location)
{
double theta0Apparent = AASSidereal.ApparentGreenwichSiderealTime(jd);
//hour angle in hours
double H = theta0Apparent - location.longitude / 15d - this.ra;
AAS2DCoordinate local = AASCoordinateTransformation.Equatorial2Horizontal(H, this.dec, location.latitude);
double az = local.X;
double alt = local.Y;
double x = Math.Cos(alt * M.DEG2RAD) * Math.Sin(az * 15.0f * M.DEG2RAD);
double y = Math.Sin(alt * M.DEG2RAD);
double z = -Math.Cos(alt * M.DEG2RAD) * Math.Cos(az * 15.0f * M.DEG2RAD);
return(new Vector3((float)x, (float)y, (float)z));
}
public Orientation CoordinateToOrientation(Coordinate coordinate, DateTime datetime)
{
if (coordinate == null)
{
throw new ArgumentException("Coordinate cannot be null");
}
AASDate date = new AASDate(datetime.Year, datetime.Month, datetime.Day, datetime.Hour, datetime.Minute, datetime.Second, true);
double ApparentGreenwichSiderealTime = AASSidereal.ApparentGreenwichSiderealTime(date.Julian);
double LongtitudeAsHourAngle = AASCoordinateTransformation.DegreesToHours(Location.Longitude);
double LocalHourAngle = ApparentGreenwichSiderealTime - LongtitudeAsHourAngle - coordinate.RightAscension;
AAS2DCoordinate Horizontal = AASCoordinateTransformation.Equatorial2Horizontal(LocalHourAngle, coordinate.Declination, Location.Latitude);
// Since AASharp considers south zero, flip the orientation 180 degrees
Horizontal.X += 180;
if (Horizontal.X > 360)
{
Horizontal.X -= 360;
}
return(new Orientation(Horizontal.X, Horizontal.Y));
}
