/// <summary>
/// Creates a instance of the class from geodetic coordinates.
/// </summary>
/// <param name="geo">The geocentric coordinates.</param>
/// <param name="date">The Julian date.</param>
/// <remarks>
/// Assumes the Earth is an oblate spheroid.
/// Reference: The 1992 Astronomical Almanac, page K11
/// Reference: www.celestrak.com (Dr. T.S. Kelso)
/// </remarks>
public Eci(Geo geo, Julian date)
{
double lat = geo.LatitudeRad;
double lon = geo.LongitudeRad;
double alt = geo.Altitude;
// Calculate Local Mean Sidereal Time (theta)
double theta = date.ToLmst(lon);
double c = 1.0 / Math.Sqrt(1.0 + Globals.F * (Globals.F - 2.0) *
Globals.Sqr(Math.Sin(lat)));
double s = Globals.Sqr(1.0 - Globals.F) * c;
double achcp = (Globals.Xkmper * c + alt) * Math.Cos(lat);
Position = new Vector();
Position.X = achcp * Math.Cos(theta); // km
Position.Y = achcp * Math.Sin(theta); // km
Position.Z = (Globals.Xkmper * s + alt) * Math.Sin(lat); // km
Position.W = Math.Sqrt(Globals.Sqr(Position.X) +
Globals.Sqr(Position.Y) +
Globals.Sqr(Position.Z)); // range, km
Velocity = new Vector();
double mfactor = Globals.TwoPi * (Globals.OmegaE / Globals.SecPerDay);
Velocity.X = -mfactor * Position.Y; // km / sec
Velocity.Y = mfactor * Position.X; // km / sec
Velocity.Z = 0.0; // km / sec
Velocity.W = Math.Sqrt(Globals.Sqr(Velocity.X) + // range rate km/sec^2
Globals.Sqr(Velocity.Y));
}
/// <summary>
/// Create a Site object from Geo object.
/// </summary>
/// <param name="geo">The Geo object.</param>
public Site(Geo geo)
{
Geo = new Geo(geo);
}
/// <summary>
/// Standard constructor.
/// </summary>
/// <param name="degLat">Latitude in degrees (negative south).</param>
/// <param name="degLon">Longitude in degrees (negative west).</param>
/// <param name="kmAlt">Altitude in kilometers.</param>
/// <param name="model">The earth ellipsoid model.</param>
public Site(double degLat, double degLon, double kmAlt)
{
Geo = new Geo(Globals.ToRadians(degLat),
Globals.ToRadians(degLon),
kmAlt);
}
/// <summary>
/// Creates a Geo object from a source Geo object.
/// </summary>
/// <param name="geo">The source Geo object.</param>
public Geo(Geo geo)
{
LatitudeRad = geo.LatitudeRad;
LongitudeRad = geo.LongitudeRad;
Altitude = geo.Altitude;
}
/// <summary>
/// Constructor accepting Geo and Julian objects.
/// </summary>
/// <param name="geo">The Geo object.</param>
/// <param name="date">The Julian date.</param>
public GeoTime(Geo geo, Julian date)
: base(geo)
{
Date = date;
}
/// <summary>
/// Creates a new instance of the class from geodetic coordinates.
/// </summary>
/// <param name="geo">The geodetic coordinates.</param>
/// <param name="date">The time associated with the ECI coordinates.</param>
public EciTime(Geo geo, Julian date)
: base(geo, date)
{
Date = date;
}