// ///////////////////////////////////////////////////////////////////
// Calculate the ECI coordinates of the location "geo" at time "date".
// Assumes geo coordinates are km-based.
// Assumes the earth is an oblate spheroid as defined in WGS '72.
// Reference: The 1992 Astronomical Almanac, page K11
// Reference: www.celestrak.com (Dr. TS Kelso)
public Eci(CoordGeo geo, Julian date)
{
m_VecUnits = VecUnits.UNITS_KM;
double mfactor = Globals.TWOPI * (Globals.OMEGA_E / Globals.SEC_PER_DAY);
double lat = geo.m_Lat;
double lon = geo.m_Lon;
double alt = geo.Altitude.Kilometers;
// 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);
m_date = date;
m_pos = new Vector();
m_pos.X = achcp * Math.Cos(theta); // km
m_pos.Y = achcp * Math.Sin(theta); // km
m_pos.Z = (Globals.XKMPER * s + alt) * Math.Sin(lat); // km
m_pos.W = Math.Sqrt(Globals.Sqr(m_pos.X) +
Globals.Sqr(m_pos.Y) +
Globals.Sqr(m_pos.Z)); // range, km
m_vel = new Vector();
m_vel.X = -mfactor * m_pos.Y; // km / sec
m_vel.Y = mfactor * m_pos.X;
m_vel.Z = 0.0;
m_vel.W = Math.Sqrt(Globals.Sqr(m_vel.X) + // range rate km/sec^2
Globals.Sqr(m_vel.Y));
}
public Eci(Vector pos, Vector vel, Julian date, bool IsAeUnits)
{
m_pos = pos;
m_vel = vel;
m_date = date;
m_VecUnits = (IsAeUnits ? VecUnits.UNITS_AE : VecUnits.UNITS_NONE);
}
/// <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));
}
// ///////////////////////////////////////////////////////////////////
public Orbit(Tle tle)
{
m_NoradModel = null;
m_tle = tle;
m_tle.Initialize();
int epochYear = (int)m_tle.getField(Tle.eField.FLD_EPOCHYEAR);
double epochDay = m_tle.getField(Tle.eField.FLD_EPOCHDAY);
if (epochYear < 57)
epochYear += 2000;
else
epochYear += 1900;
m_jdEpoch = new Julian(epochYear, epochDay);
m_secPeriod = -1.0;
// Recover the original mean motion and semimajor axis from the
// input elements.
double mm = mnMotion();
double rpmin = mm * 2 * Globals.PI / Globals.MIN_PER_DAY; // rads per minute
double a1 = Math.Pow(Globals.XKE / rpmin, Globals.TWOTHRD);
double e = Eccentricity();
double i = Inclination();
double temp = (1.5 * Globals.CK2 * (3.0 * Globals.Sqr(Math.Cos(i)) - 1.0) /
Math.Pow(1.0 - e * e, 1.5));
double delta1 = temp / (a1 * a1);
double a0 = a1 *
(1.0 - delta1 *
((1.0 / 3.0) + delta1 *
(1.0 + 134.0 / 81.0 * delta1)));
double delta0 = temp / (a0 * a0);
m_mnMotionRec = rpmin / (1.0 + delta0);
m_aeAxisSemiMinorRec = a0 / (1.0 - delta0);
m_aeAxisSemiMajorRec = m_aeAxisSemiMinorRec / Math.Sqrt(1.0 - (e * e));
m_kmPerigeeRec = Globals.XKMPER * (m_aeAxisSemiMinorRec * (1.0 - e) - Globals.AE);
if (2.0 * Globals.PI / m_mnMotionRec >= 225.0)
{
// SDP4 : period >= 225 minutes.
m_NoradModel = new NoradSDP4(this);
}
else
{
// SGP4 : period < 225 minutes
m_NoradModel = new NoradSGP4(this);
}
}
// /////////////////////////////////////////////////////////////////////
public TimeSpan Diff(Julian date)
{
const double TICKS_PER_DAY = 8.64e11; // 1 tick = 100 nanoseconds
return new TimeSpan((long)((m_Date - date.m_Date) * TICKS_PER_DAY));
}
/// <summary>
/// Returns the ECI coordinates of the site at the given time.
/// </summary>
/// <param name="date">Time of position calculation.</param>
/// <returns>The site's ECI coordinates.</returns>
public EciTime GetPosition(Julian date)
{
return new EciTime(Geo, date);
}
/// <summary>
/// Creates a new instance of the class given ECI coordinates.
/// </summary>
/// <param name="eci">The ECI coordinates.</param>
/// <param name="date">The Julian date.</param>
public Geo(Eci eci, Julian date)
: this(eci.Position,
(Globals.AcTan(eci.Position.Y, eci.Position.X) - date.ToGmst()) % Globals.TwoPi)
{
}
/// <summary>
/// Creates a new instance of the class from the given components.
/// </summary>
/// <param name="radAz">Azimuth, in radians.</param>
/// <param name="radEl">Elevation, in radians.</param>
/// <param name="range">Range, in kilometers.</param>
/// <param name="rangeRate">Range rate, in kilometers per second. A negative
/// range rate means "towards the observer".</param>
/// <param name="date">The time associated with the coordinates.</param>
public TopoTime(double radAz, double radEl, double range, double rangeRate, Julian date)
: base(radAz, radEl, range, rangeRate)
{
Date = date;
}
/// <summary>
/// Creates a new instance of the class from ECI-time coordinates.
/// </summary>
/// <param name="eci">The ECI coordinates.</param>
/// <param name="date">The time associated with the ECI coordinates.</param>
public EciTime(Eci eci, Julian date)
: this(eci.Position, eci.Velocity, date)
{
}
// ///////////////////////////////////////////////////////////////////
public Orbit(Tle tle)
{
m_NoradModel = null;
m_tle = tle;
m_jdEpoch = m_tle.EpochJulian;
m_secPeriod = -1.0;
// Recover the original mean motion and semimajor axis from the
// input elements.
double mm = mnMotion;
double rpmin = mm * 2 * Globals.PI / Globals.MIN_PER_DAY; // rads per minute
double a1 = Math.Pow(Globals.XKE / rpmin, Globals.TWOTHRD);
double e = Eccentricity;
double i = Inclination;
double temp = (1.5 * Globals.CK2 * (3.0 * Globals.Sqr(Math.Cos(i)) - 1.0) /
Math.Pow(1.0 - e * e, 1.5));
double delta1 = temp / (a1 * a1);
double a0 = a1 *
(1.0 - delta1 *
((1.0 / 3.0) + delta1 *
(1.0 + 134.0 / 81.0 * delta1)));
double delta0 = temp / (a0 * a0);
m_mnMotionRec = rpmin / (1.0 + delta0);
m_aeAxisSemiMinorRec = a0 / (1.0 - delta0);
m_aeAxisSemiMajorRec = m_aeAxisSemiMinorRec / Math.Sqrt(1.0 - (e * e));
m_kmPerigeeRec = Globals.XKMPER * (m_aeAxisSemiMajorRec * (1.0 - e) - Globals.AE);
m_kmApogeeRec = Globals.XKMPER * (m_aeAxisSemiMajorRec * (1.0 + e) - Globals.AE);
if (2.0 * Globals.PI / m_mnMotionRec >= 225.0)
{
// SDP4 - period >= 225 minutes.
m_NoradModel = new NoradSDP4(this);
}
else
{
// SGP4 - period < 225 minutes
m_NoradModel = new NoradSGP4(this);
}
}
/// <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>
/// Standard constructor.
/// </summary>
/// <param name="radLat">Latitude, in radians. Negative values indicate
/// latitude south.</param>
/// <param name="radLon">Longitude, in radians. Negative value indicate longitude
/// west.</param>
/// <param name="kmAlt">Altitude above the ellipsoid model, in kilometers.</param>
/// <param name="date">The time associated with the coordinates.</param>
public GeoTime(double radLat, double radLon, double kmAlt, Julian date)
: base(radLat, radLon, kmAlt)
{
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;
}
public Eci(Vector pos, Vector vel, Julian date, bool IsAeUnits)
{
m_Position = pos;
m_Velocity = vel;
m_Date = date;
m_VectorUnits = (IsAeUnits ? VectorUnits.Ae : VectorUnits.None);
}
/// <summary>
/// Creates a new instance of the class from ECI coordinates.
/// </summary>
/// <param name="eci">The ECI coordinates.</param>
/// <param name="date">The Julian date.</param>
public GeoTime(Eci eci, Julian date)
: base(eci, date)
{
Date = date;
}
// ///////////////////////////////////////////////////////////////////
// Calculate the ECI coordinates of the location "geo" at time "date".
// Assumes geo coordinates are km-based.
// Assumes the earth is an oblate spheroid as defined in WGS '72.
// Reference: The 1992 Astronomical Almanac, page K11
// Reference: www.celestrak.com (Dr. TS Kelso)
public Eci(CoordGeo geo, Julian date)
{
m_VectorUnits = VectorUnits.Km;
double mfactor = Globals.TWOPI * (Globals.OMEGA_E / Globals.SEC_PER_DAY);
double lat = geo.Latitude;
double lon = geo.Longitude;
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);
m_Date = date;
m_Position = new Vector();
m_Position.X = achcp * Math.Cos(theta); // km
m_Position.Y = achcp * Math.Sin(theta); // km
m_Position.Z = (Globals.XKMPER * s + alt) * Math.Sin(lat); // km
m_Position.W = Math.Sqrt(Globals.Sqr(m_Position.X) +
Globals.Sqr(m_Position.Y) +
Globals.Sqr(m_Position.Z)); // range, km
m_Velocity = new Vector();
m_Velocity.X = -mfactor * m_Position.Y; // km / sec
m_Velocity.Y = mfactor * m_Position.X;
m_Velocity.Z = 0.0;
m_Velocity.W = Math.Sqrt(Globals.Sqr(m_Velocity.X) + // range rate km/sec^2
Globals.Sqr(m_Velocity.Y));
}
/// <summary>
/// Creates an instance of the class from topo and time information.
/// </summary>
/// <param name="topo"></param>
/// <param name="date"></param>
public TopoTime(Topo topo, Julian date)
: base(topo.AzimuthRad, topo.ElevationRad, topo.Range, topo.RangeRate)
{
Date = date;
}
// ///////////////////////////////////////////////////////////////////////////
// getPosition()
// Return the ECI coordinate of the site at the given time.
public Eci getPosition(Julian date)
{
return new Eci(m_geo, date);
}
/// <summary>
/// Creates an instance of the class with the given position, velocity, and time.
/// </summary>
/// <param name="pos">The position vector.</param>
/// <param name="vel">The velocity vector.</param>
/// <param name="date">The time associated with the position.</param>
public EciTime(Vector pos, Vector vel, Julian date)
: base(pos, vel)
{
Date = date;
}
