public void EquatorialToHorizontal()
{
// Apparent equatorial coordinates of Venus
var eq = new CrdsEquatorial(new HMS("23h 09m 16.641s"), new DMS("-6* 43' 11.61''"));
// Geographical coordinates of US Naval Observatory at Washington, DC
var geo = new CrdsGeographical(new DMS("+38* 55' 17''"), new DMS("+77* 03' 56''"));
// Date of observation
var jd = new Date(new DateTime(1987, 4, 10, 19, 21, 0, DateTimeKind.Utc)).ToJulianDay();
// Mean sidereal time at Greenwich
var theta0 = Date.MeanSiderealTime(jd);
Assert.AreEqual(new HMS("8h 34m 57.0896s"), new HMS(theta0));
// Nutation elements
var nutation = Nutation.NutationElements(jd);
// True obliquity
var epsilon = Date.TrueObliquity(jd, nutation.deltaEpsilon);
// Apparent sidereal time at Greenwich
theta0 = Date.ApparentSiderealTime(jd, nutation.deltaPsi, epsilon);
Assert.AreEqual(new HMS("8h 34m 56.853s"), new HMS(theta0));
// Expected local horizontal coordinates of Venus
var hor = eq.ToHorizontal(geo, theta0);
Assert.AreEqual(15.1249, hor.Altitude, 1e-4);
Assert.AreEqual(68.0336, hor.Azimuth, 1e-4);
}
public Sky()
{
// Ecliptic
LineEcliptic.FromHorizontal = (h) =>
{
var eq = h.ToEquatorial(GeoLocation, LocalSiderealTime);
var ec = eq.ToEcliptical(Epsilon);
return(new GridPoint(ec.Lambda, ec.Beta));
};
LineEcliptic.ToHorizontal = (c) =>
{
var ec = new CrdsEcliptical(c.Longitude, c.Latitude);
var eq = ec.ToEquatorial(Epsilon);
return(eq.ToHorizontal(GeoLocation, LocalSiderealTime));
};
// Horizontal grid
GridHorizontal.FromHorizontal = (h) => new GridPoint(h.Azimuth, h.Altitude);
GridHorizontal.ToHorizontal = (c) => new CrdsHorizontal(c.Longitude, c.Latitude);
// Equatorial grid
GridEquatorial.FromHorizontal = (h) =>
{
var eq = h.ToEquatorial(GeoLocation, LocalSiderealTime);
return(new GridPoint(eq.Alpha, eq.Delta));
};
GridEquatorial.ToHorizontal = (c) =>
{
var eq = new CrdsEquatorial(c.Longitude, c.Latitude);
return(eq.ToHorizontal(GeoLocation, LocalSiderealTime));
};
}
/// <summary>
/// Gets drawing rotation of image, measured clockwise from
/// a point oriented to top of the screen towards North celestial pole point
/// </summary>
/// <param name="eq">Equatorial coordinates of a central point of a body.</param>
/// <returns></returns>
public static float GetRotationTowardsNorth(this IMapContext map, CrdsEquatorial eq)
{
// Coordinates of center of a body (image) to be rotated
PointF p = map.Project(eq.ToHorizontal(map.GeoLocation, map.SiderealTime));
// Point directed to North celestial pole
PointF pNorth = map.Project((eq + new CrdsEquatorial(0, 1)).ToHorizontal(map.GeoLocation, map.SiderealTime));
// Clockwise rotation
return(LineInclinationY(p, pNorth));
}
public override void Initialize()
{
// Ecliptic
LineEcliptic.FromHorizontal = (h, ctx) =>
{
var eq = h.ToEquatorial(ctx.GeoLocation, ctx.SiderealTime);
var ec = eq.ToEcliptical(ctx.Epsilon);
return(new GridPoint(ec.Lambda, ec.Beta));
};
LineEcliptic.ToHorizontal = (c, ctx) =>
{
var ec = new CrdsEcliptical(c.Longitude, c.Latitude);
var eq = ec.ToEquatorial(ctx.Epsilon);
return(eq.ToHorizontal(ctx.GeoLocation, ctx.SiderealTime));
};
// Galactic equator
LineGalactic.FromHorizontal = (h, ctx) =>
{
var eq = h.ToEquatorial(ctx.GeoLocation, ctx.SiderealTime);
var eq1950 = Precession.GetEquatorialCoordinates(eq, peTo1950);
var gal = eq1950.ToGalactical();
return(new GridPoint(gal.l, gal.b));
};
LineGalactic.ToHorizontal = (c, ctx) =>
{
var gal = new CrdsGalactical(c.Longitude, c.Latitude);
var eq1950 = gal.ToEquatorial();
var eq = Precession.GetEquatorialCoordinates(eq1950, peFrom1950);
return(eq.ToHorizontal(ctx.GeoLocation, ctx.SiderealTime));
};
// Meridian line
LineMeridian.FromHorizontal = (h, ctx) => new GridPoint(0, h.Azimuth - 180);
LineMeridian.ToHorizontal = (c, context) => new CrdsHorizontal(0, c.Longitude - 180);
// Horizontal grid
GridHorizontal.FromHorizontal = (h, ctx) => new GridPoint(h.Azimuth, h.Altitude);
GridHorizontal.ToHorizontal = (c, context) => new CrdsHorizontal(c.Longitude, c.Latitude);
// Equatorial grid
GridEquatorial.FromHorizontal = (h, ctx) =>
{
var eq = h.ToEquatorial(ctx.GeoLocation, ctx.SiderealTime);
return(new GridPoint(eq.Alpha, eq.Delta));
};
GridEquatorial.ToHorizontal = (c, ctx) =>
{
var eq = new CrdsEquatorial(c.Longitude, c.Latitude);
return(eq.ToHorizontal(ctx.GeoLocation, ctx.SiderealTime));
};
}