fr.cnes.sirius.patrius.time

Class LocalTimeAngle

java.lang.Object

fr.cnes.sirius.patrius.time.LocalTimeAngle

All Implemented Interfaces:

Serializable

public class LocalTimeAngle
extends Object
implements Serializable

This class provides methods to compute local time angle (true local time angle and mean local time angle).

The local time is represented by the angle between the projections of the Sun and the satellite in the equatorial plane; therefore this angle is equal to zero when the local time is 12.00h and Π when the local time is 0.00h (Local Time In Hours = 12.00h + local time angle * 12 / Π).

Since:

3.0

Version:

$Id: LocalTimeAngle.java 17582 2017-05-10 12:58:16Z bignon $

Author:

Emmanuel Bignon

See Also:

Serialized Form

Concurrency :

not thread-safe

Constructor Summary

Constructors

Constructor and Description
LocalTimeAngle(PVCoordinatesProvider sunEphemeris) Constructor

Method Summary

Modifier and Type	Method and Description
double	computeEquationOfTime(AbsoluteDate date) Compute equation of time in TIRF in the range [-43200s; 43200s].
double	computeMeanLocalTimeAngle(AbsoluteDate date, Vector3D pos, Frame frame) Compute mean local time angle in TIRF frame in the range [-Π, Π[.
double	computeMeanLocalTimeAngle(Orbit orbit) Compute mean local time angle in TIRF frame in the range [-Π, Π[.
double	computeRAANFromMeanLocalTime(AbsoluteDate date, double meanLocalTime) Compute RAAN from mean local time angle.
double	computeRAANFromTrueLocalTime(AbsoluteDate date, double trueLocalTime, Frame frame) Compute RAAN from true local time angle
double	computeTrueLocalTimeAngle(AbsoluteDate date, Vector3D pos, Frame frame) Compute true local time angle in TIRF frame in the range [-Π, Π[.
double	computeTrueLocalTimeAngle(Orbit orbit) Compute true local time angle in TIRF frame in the range [-Π, Π[.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

LocalTimeAngle

public LocalTimeAngle(PVCoordinatesProvider sunEphemeris)

Constructor

Parameters:

sunEphemeris - Sun ephemeris

Method Detail

computeTrueLocalTimeAngle

public double computeTrueLocalTimeAngle(AbsoluteDate date,
                                        Vector3D pos,
                                        Frame frame)
                                 throws PatriusException

Compute true local time angle in TIRF frame in the range [-Π, Π[.

Parameters:

date - date

pos - position in provided frame frame

frame - frame in which position is defined

Returns:

true local time angle in TIRF frame in rad (Local Time In Hours = 12.00h + local time angle * 12 / Π)

Throws:

PatriusException - thrown if Sun PV coordinates could not be retrieved

computeTrueLocalTimeAngle

public double computeTrueLocalTimeAngle(Orbit orbit)
                                 throws PatriusException

Compute true local time angle in TIRF frame in the range [-Π, Π[.

Parameters:

orbit - orbit

Returns:

true local time in TIRF frame in rad (Local Time In Hours = 12.00h + local time angle * 12 / Π)

Throws:

PatriusException - thrown if Sun PV coordinates could not be retrieved

computeMeanLocalTimeAngle

public double computeMeanLocalTimeAngle(AbsoluteDate date,
                                        Vector3D pos,
                                        Frame frame)
                                 throws PatriusException

Compute mean local time angle in TIRF frame in the range [-Π, Π[.

Mean local time is equal to true local time minus equation of time.

Parameters:

date - date

pos - position in provided frame

frame - frame in which position is defined

Returns:

mean local time in TIRF frame in rad (Local Time In Hours = 12.00h + local time angle * 12 / Π)

Throws:

PatriusException - thrown if true local time could not be computed

computeMeanLocalTimeAngle

public double computeMeanLocalTimeAngle(Orbit orbit)
                                 throws PatriusException

Compute mean local time angle in TIRF frame in the range [-Π, Π[.

Mean local time is equal to true local time minus equation of time.

Parameters:

orbit - orbit

Returns:

mean local time in TIRF frame in rad (Local Time In Hours = 12.00h + local time angle * 12 / Π)

Throws:

PatriusException - thrown if Sun PV coordinates could not be retrieved

computeEquationOfTime

public double computeEquationOfTime(AbsoluteDate date)
                             throws PatriusException

Compute equation of time in TIRF in the range [-43200s; 43200s].

Parameters:

date - date

Returns:

equation of time in TIRF frame (in s)

Throws:

PatriusException - thrown if equation of time could not be computed

computeRAANFromTrueLocalTime

public double computeRAANFromTrueLocalTime(AbsoluteDate date,
                                           double trueLocalTime,
                                           Frame frame)
                                    throws PatriusException

Compute RAAN from true local time angle

Parameters:

date - date

trueLocalTime - true local time angle in rad

frame - frame for which Earth equator should be considered. This frame should be pseudo-inertial

Returns:

RAAN corresponding to provided local time

Throws:

PatriusException - thrown if Sun position could not be retrieved in frame or frame is not pseudo-inertial

computeRAANFromMeanLocalTime

public double computeRAANFromMeanLocalTime(AbsoluteDate date,
                                           double meanLocalTime)
                                    throws PatriusException

Compute RAAN from mean local time angle.

Parameters:

date - date

meanLocalTime - mean local time angle in rad

Returns:

RAAN corresponding to provided local time

Throws:

PatriusException - thrown if sideral time could not be computed