// Degrees per radian
static void Main0(string[] args)
{
// Position and velocity
Geo.Algorithm.Vector r = new Geo.Algorithm.Vector(+10000.0e3, +40000.0e3, -5000.0e3); // [m]
Geo.Algorithm.Vector v = new Geo.Algorithm.Vector(-1.500e3, +1.000e3, -0.100e3); // [m/s]
// Variables
int i;
Geo.Algorithm.Vector y = new Geo.Algorithm.Vector(6), Kep = new Geo.Algorithm.Vector(6);
// Orbital elements
y = r.Stack(v);
Kep = Kepler.Elements(OrbitConsts.GM_Earth, y);
// Output
var info = "Exercise 2-3: Osculating elements";
Console.WriteLine(info);
info = "State vector:";
Console.WriteLine(info);
info = " Position ";
Console.Write(info);
for (i = 0; i < 3; i++)
{
Console.Write(r[i] / 1000.0 + ", ");
//Console.WriteLine(info);
}
;
info = " [km]";
Console.WriteLine(info);
info = " Velocity ";
Console.Write(info);
for (i = 0; i < 3; i++)
{
Console.Write(v[i] / 1000.0 + ", ");
}
Console.WriteLine(" [km/s]");
Console.WriteLine();
Console.WriteLine("Orbital elements:");
Console.WriteLine(" Semimajor axis " + String.Format("{0:f3}", (Kep[0] / 1000.0)) + " km");
Console.WriteLine(" Eccentricity " + String.Format("{0:f3}", Kep[1]));
Console.WriteLine(" Inclination " + String.Format("{0:f3}", Kep[2] * OrbitConsts.DegPerRad) + " deg");
Console.WriteLine(" RA ascend. node " + String.Format("{0:f3}", Kep[3] * OrbitConsts.DegPerRad) + " deg");
Console.WriteLine(" Arg. of perigee " + String.Format("{0:f3}", Kep[4] * OrbitConsts.DegPerRad) + " deg");
Console.WriteLine(" Mean anomaly " + String.Format("{0:f3}", Kep[5] * OrbitConsts.DegPerRad) + " deg");
Console.ReadKey();
}
static void Main0(string[] args)
{
// Variables
int i; // Loop counter
double MJD_GPS, MJD_TT; // Modified Julian Date (GPS,TT)
double MJD_UTC, MJD_UT1; // Modified Julian Date (UTC,UT1)
Matrix P = new Matrix(3, 3), N = new Matrix(3, 3); // Precession/nutation matrix
Matrix Theta = new Matrix(3, 3); // Sidereal Time matrix
Matrix S = new Matrix(3, 3), dTheta = new Matrix(3, 3); // and derivative
Matrix Pi = new Matrix(3, 3); // Polar motion matrix
Matrix U = new Matrix(3, 3), dU = new Matrix(3, 3); // ICRS to ITRS transformation and derivative
Vector r_WGS = new Vector(3), v_WGS = new Vector(3); // Position/velocity in the Earth-fixed frame
Vector r = new Vector(3), v = new Vector(3); // Position/velocity in the ICRS
Vector y = new Vector(6), Kep = new Vector(6); // Satte vector and Keplerian elements
// Header
var endl = "\r\n";
var info = "Exercise 5-2: Velocity in the Earth-fixed frame"
+ endl + endl;
Console.WriteLine(info);
// Earth Orientation Parameters (UT1-UTC[s],UTC-TAI[s], x["], y["])
// (from IERS Bulletin B #135 and C #16; valid for 1999/03/04 0:00 UTC)
IERS IERS = new IERS(0.6492332, -32.0, 0.06740, 0.24173);
// Date
MJD_GPS = DateUtil.DateToMjd(1999, 03, 04, 0, 0, 0.0);
MJD_UTC = MJD_GPS - IERS.GetGPS_UTC(MJD_GPS) / 86400.0;
MJD_UT1 = MJD_UTC + IERS.GetUT1_UTC(MJD_UTC) / 86400.0;
MJD_TT = MJD_UTC + IERS.GetTT_UTC(MJD_UTC) / 86400.0;
// Earth-fixed state vector of GPS satellite #PRN15
// (from NIMA ephemeris nim09994.eph; WGS84(G873) system)
r_WGS = new Vector(19440.953805e+3, 16881.609273e+3, -6777.115092e+3); // [m]
v_WGS = new Vector(-8111.827456e-1, -2573.799137e-1, -30689.508125e-1); // [m/s]
// ICRS to ITRS transformation matrix and derivative
P = IERS.PrecessionMatrix(OrbitConsts.MJD_J2000, MJD_TT); // IAU 1976 Precession
N = IERS.NutMatrix(MJD_TT); // IAU 1980 Nutation
Theta = IERS.GreenwichHourAngleMatrix(MJD_UT1); // Earth rotation
Pi = IERS.PoleMatrix(MJD_UTC); // Polar motion
S[0, 1] = 1.0; S[1, 0] = -1.0; // Derivative of Earth rotation
dTheta = OrbitConsts.RotationSpeedOfEarth_Rad * S * Theta; // matrix [1/s]
U = Pi * Theta * N * P; // ICRS to ITRS transformation
dU = Pi * dTheta * N * P; // Derivative [1/s]
// Transformation from WGS to ICRS
r = U.Transpose() * r_WGS;
v = U.Transpose() * v_WGS + dU.Transpose() * r_WGS;
// Orbital elements
y = r.Stack(v);
Kep = Kepler.Elements(OrbitConsts.GM_Earth, y);
// Output
info = "Date" + endl + endl
+ " " + DateUtil.MjdToDateTimeString(MJD_GPS) + " GPS" + endl
+ " " + DateUtil.MjdToDateTimeString(MJD_UTC) + " UTC" + endl
+ " " + DateUtil.MjdToDateTimeString(MJD_UT1) + " UT1" + endl
+ " " + DateUtil.MjdToDateTimeString(MJD_TT) + " TT " + endl + endl;
Console.WriteLine(info);
info = "WGS84 (G873) State vector:" + endl + endl;
info += " Position ";
for (i = 0; i < 3; i++)
{
info += String.Format("{0, 10:F6}", r_WGS[i] / 1000.0);
}
;
info += " [km]";
Console.WriteLine(info);
info = " Velocity ";
for (i = 0; i < 3; i++)
{
info += String.Format("{0, 10:F6}", v_WGS[i] / 1000.0);
}
;
info += " [km/s]" + endl + endl;
Console.WriteLine(info);
info = "ICRS-ITRS transformation" + endl + endl
+ String.Format("{0, 10:F6}", U) + endl;
info += "Derivative of ICRS-ITRS transformation [10^(-4)/s]" + endl + endl
+ String.Format("{0, 10:F6}", dU * 1.0e4) + endl;
info += "ICRS State vector:" + endl;
Console.WriteLine(info);
info = " Position ";
for (i = 0; i < 3; i++)
{
info += String.Format("{0, 14:F6}", r[i] / 1000.0);
}
;
info += " [km]";
Console.WriteLine(info);
info = " Velocity ";
for (i = 0; i < 3; i++)
{
info += String.Format("{0, 14:F6}", v[i] / 1000.0);
}
;
info += " [km/s]" + endl + endl;
Console.WriteLine(info);
info = "Orbital elements:" + endl + endl
+ " Semimajor axis " + String.Format("{0, 10:F3}", Kep[0] / 1000.0) + " km" + endl
+ " Eccentricity " + String.Format("{0, 10:F7}", Kep[1]) + endl
+ " Inclination " + String.Format("{0, 10:F3}", Kep[2] * OrbitConsts.DegPerRad) + " deg" + endl
+ " RA ascend. node " + String.Format("{0, 10:F3}", Kep[3] * OrbitConsts.DegPerRad) + " deg" + endl
+ " Arg. of perigee " + String.Format("{0, 10:F3}", Kep[4] * OrbitConsts.DegPerRad) + " deg" + endl
+ " Mean anomaly " + String.Format("{0, 10:F3}", Kep[5] * OrbitConsts.DegPerRad) + " deg" + endl;
Console.WriteLine(info);
Console.ReadKey();
}
static void Main0(string[] args)
{
string endl = "\r\n";
// Ground station
Vector R_Sta = new Geo.Algorithm.Vector(+1344.143e3, +6068.601e3, +1429.311e3); // Position vector
GeoCoord Sta = CoordTransformer.XyzToGeoCoord(new XYZ(R_Sta.OneDimArray)); //new GeoCoord(R_Sta, OrbitConsts.RadiusOfEarth, OrbitConsts.FlatteningOfEarth);// Geodetic coordinates
// Observations
ObsType[] Obs = new ObsType[] {
new ObsType(DateUtil.DateToMjd(1999, 04, 02, 00, 30, 00.0), 132.67 * OrbitConsts.RadPerDeg, 32.44 * OrbitConsts.RadPerDeg, 16945.450e3),
new ObsType(DateUtil.DateToMjd(1999, 04, 02, 03, 00, 00.0), 123.08 * OrbitConsts.RadPerDeg, 50.06 * OrbitConsts.RadPerDeg, 37350.340e3)
};
// Variables
int i, j;
double Az, El, d;
Geo.Algorithm.Vector s = new Geo.Algorithm.Vector(3);
Geo.Algorithm.Vector[] r = new Geo.Algorithm.Vector[2];
// Transformation to local tangent coordinates
Matrix E = Sta.ToLocalNez_Matrix();
// Convert observations
for (i = 0; i < 2; i++)
{
// Earth rotation
Matrix U = Matrix.RotateZ3D(IERS.GetGmstRad(Obs[i].Mjd_UTC));
// Topocentric position vector
Az = Obs[i].Azimuth; El = Obs[i].Elevation; d = Obs[i].Range;
s = d * Geo.Algorithm.Vector.VecPolar(OrbitConsts.PI / 2 - Az, El);
// Inertial position vector
r[i] = U.Transpose() * (E.Transpose() * s + R_Sta);
}
// Orbital elements
Geo.Algorithm.Vector Kep = Kepler.Elements(OrbitConsts.GM_Earth, Obs[0].Mjd_UTC, Obs[1].Mjd_UTC, r[0], r[1]);
// Output
var info = "Exercise 2-6: Initial orbit determination" + "\r\n";
info += "Inertial positions:" + "\r\n";
info += " ";
info += "[km]" + " [km]" + " [km]";
Console.WriteLine(info);
for (i = 0; i < 2; i++)
{
info = " " + DateUtil.MjdToDateTimeString(Obs[i].Mjd_UTC);
for (j = 0; j < 3; j++)
{
info += " " + String.Format("{0, 12:F3}", r[i][j] / 1000.0);
}
;
Console.WriteLine(info);
}
Console.WriteLine();
info = "Orbital elements:" + "\r\n"
+ " Epoch (1st obs.) " + DateUtil.MjdToDateTimeString(Obs[0].Mjd_UTC) + endl
+ " Semimajor axis " + String.Format("{0, 10:F3}", Kep[0] / 1000.0) + " km" + endl
+ " Eccentricity " + String.Format("{0, 10:F3}", Kep[1]) + endl
+ " Inclination " + String.Format("{0, 10:F3}", Kep[2] * OrbitConsts.DegPerRad) + " deg" + endl
+ " RA ascend. node " + String.Format("{0, 10:F3}", Kep[3] * OrbitConsts.DegPerRad) + " deg" + endl
+ " Arg. of perigee " + String.Format("{0, 10:F3}", Kep[4] * OrbitConsts.DegPerRad) + " deg" + endl
+ " Mean anomaly " + String.Format("{0, 10:F3}", Kep[5] * OrbitConsts.DegPerRad) + " deg" + endl;
Console.WriteLine(info);
Console.ReadKey();
}