// ///////////////////////////////////////////////////////////////////
// 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 a new instance of the class with the given position and
/// velocity components.
/// </summary>
/// <param name="pos">The position vector.</param>
/// <param name="vel">The velocity vector.</param>
public Eci(Vector pos, Vector vel, Julian date, bool IsAeUnits)
{
Position = pos;
Velocity = vel;
jDate = date;
Units = (IsAeUnits ? VectorUnits.Ae : VectorUnits.None);
}
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);
}
// ///////////////////////////////////////////////////////////////////////////
// Convert the position and velocity vector units from Globals.AE-based units
// to kilometer based units.
public void ae2km()
{
if (UnitsAreAe())
{
MulPos(Globals.XKMPER / Globals.AE); // km
MulVel((Globals.XKMPER / Globals.AE) * (Globals.MIN_PER_DAY / 86400)); // km/sec
m_VectorUnits = VectorUnits.Km;
}
}
// ///////////////////////////////////////////////////////////////////////////
// Convert the position and velocity vector units from Globals.AE-based units
// to kilometer based units.
public void ae2km()
{
if (UnitsAreAe())
{
MulPos(Globals.XKMPER / Globals.AE); // km
MulVel((Globals.XKMPER / Globals.AE) * (Globals.MIN_PER_DAY / 86400)); // km/sec
m_VectorUnits = VectorUnits.Km;
}
}
// ///////////////////////////////////////////////////////////////////
// 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));
}
public void SetUnitsKm() { Units = VectorUnits.Km; }
public void SetUnitsAe() { Units = VectorUnits.Ae; }
public Eci()
{
m_VectorUnits = VectorUnits.None;
}
public Eci()
{
m_VectorUnits = VectorUnits.None;
}
public void SetUnitsKm()
{
Units = VectorUnits.Km;
}
public void SetUnitsAe()
{
Units = VectorUnits.Ae;
}
public void Ae2Km()
{
if (UnitsAreAe())
{
MulPos(6378.135);
MulVel(106.30225);
Units = VectorUnits.Km;
}
}
