Package org.orekit.frames

Class SingleParameterFitter

java.lang.Object

org.orekit.frames.SingleParameterFitter

All Implemented Interfaces:

Serializable

public class SingleParameterFitter
extends Object
implements Serializable

Fitter for one Earth Orientation Parameter.

Since:

12.0

Author:

Luc Maisonobe

See Also:

• PredictedEOPHistory
• EOPFitter
• SecularAndHarmonic
• Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
static final double	MOON_DRACONIC_PULSATION	Moon pulsation (one Moon draconic period).
static final double	SUN_PULSATION	Sun pulsation, one year period.

Constructor Summary

Constructors

Constructor	Description
SingleParameterFitter(double timeConstant, double convergence, int degree, double... pulsations)	Simple constructor.

Method Summary

Modifier and Type	Method	Description
static SingleParameterFitter	createDefaultDut1FitterLongTermPrediction()	Create fitter with default parameters adapted for fitting orientation parameters dUT1 and LOD for long term prediction.
static SingleParameterFitter	createDefaultDut1FitterShortTermPrediction()	Create fitter with default parameters adapted for fitting orientation parameters dUT1 and LOD for short term prediction.
static SingleParameterFitter	createDefaultNutationFitterLongTermPrediction()	Create fitter with default parameters adapted for fitting nutation parameters dx and dy for long term prediction.
static SingleParameterFitter	createDefaultNutationFitterShortTermPrediction()	Create fitter with default parameters adapted for fitting nutation parameters dx and dy for long term prediction.
static SingleParameterFitter	createDefaultPoleFitterLongTermPrediction()	Create fitter with default parameters adapted for fitting pole parameters Xp and Yp for long term prediction.
static SingleParameterFitter	createDefaultPoleFitterShortTermPrediction()	Create fitter with default parameters adapted for fitting pole parameters Xp and Yp for long term prediction.
SecularAndHarmonic	fit(EOPHistory rawHistory, ToDoubleFunction<EOPEntry> extractor)	Perform secular and harmonic fitting.

Methods inherited from class java.lang.Object

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

Field Details

SUN_PULSATION

public static final double SUN_PULSATION

Sun pulsation, one year period.

See Also:

• Constant Field Values

MOON_DRACONIC_PULSATION

public static final double MOON_DRACONIC_PULSATION

Moon pulsation (one Moon draconic period).

See Also:

• Constant Field Values

Constructor Details

SingleParameterFitter

public SingleParameterFitter(double timeConstant,
 double convergence,
 int degree,
 double... pulsations)

Simple constructor.

Parameters:

timeConstant - time constant \(\tau\) of the exponential decay weight, point weight is \(e^{\frac{t-t_0}{\tau}}\), i.e. points far in the past before \(t_0\) have smaller weights

convergence - convergence on fitted parameter

degree - degree of the polynomial model

pulsations - pulsations of harmonic part (rad/s)

Since:

12.0.1

See Also:

• createDefaultDut1FitterShortTermPrediction()
• createDefaultDut1FitterLongTermPrediction()
• createDefaultPoleFitterShortTermPrediction()
• createDefaultPoleFitterLongTermPrediction()
• createDefaultNutationFitterShortTermPrediction()
• createDefaultNutationFitterLongTermPrediction()
• SecularAndHarmonic

Method Details

fit

public SecularAndHarmonic fit(EOPHistory rawHistory,
 ToDoubleFunction<EOPEntry> extractor)

Perform secular and harmonic fitting.

Parameters:

rawHistory - EOP history to fit

extractor - extractor for Earth Orientation Parameter

Returns:

configured fitter

createDefaultDut1FitterShortTermPrediction

public static SingleParameterFitter createDefaultDut1FitterShortTermPrediction()

Create fitter with default parameters adapted for fitting orientation parameters dUT1 and LOD for short term prediction.

The main difference between these settings and the settings for long prediction is the much smaller \(\tau\). This means more weight is set to the points at the end of the history, hence forcing the fitted prediction model to be closer to these points, hence the prediction error to be smaller just after raw history end. On the other hand, this implies that the model will diverge on long term. These settings are intended when prediction is used for at most 5 days after raw EOP end.

• time constant \(\tau\) of the exponential decay set to 6 days
• convergence set to 10⁻¹² s
• polynomial part set to degree 3
• one harmonic term at SUN_PULSATION}
• one harmonic term at 2 times SUN_PULSATION}
• one harmonic term at 3 times SUN_PULSATION}
• one harmonic term at MOON_DRACONIC_PULSATION}
• one harmonic term at 2 times MOON_DRACONIC_PULSATION}
• one harmonic term at 3 times MOON_DRACONIC_PULSATION}

Returns:

fitter with default configuration for orientation parameters dUT1 and LOD

See Also:

• createDefaultDut1FitterShortTermPrediction()

createDefaultDut1FitterLongTermPrediction

public static SingleParameterFitter createDefaultDut1FitterLongTermPrediction()

Create fitter with default parameters adapted for fitting orientation parameters dUT1 and LOD for long term prediction.

The main difference between these settings and the settings for short prediction is the much larger \(\tau\). This means weight is spread throughout history, hence forcing the fitted prediction model to be remain very stable on the long term. On the other hand, this implies that the model will start with already a much larger error just after raw history end. These settings are intended when prediction is used for 5 days after raw EOP end or more.

• time constant \(\tau\) of the exponential decay set to 60 days
• convergence set to 10⁻¹² s
• polynomial part set to degree 3
• one harmonic term at SUN_PULSATION}
• one harmonic term at 2 times SUN_PULSATION}
• one harmonic term at 3 times SUN_PULSATION}
• one harmonic term at MOON_DRACONIC_PULSATION}
• one harmonic term at 2 times MOON_DRACONIC_PULSATION}
• one harmonic term at 3 times MOON_DRACONIC_PULSATION}

Returns:

fitter with default configuration for orientation parameters dUT1 and LOD

See Also:

• createDefaultDut1FitterShortTermPrediction()

createDefaultPoleFitterShortTermPrediction

public static SingleParameterFitter createDefaultPoleFitterShortTermPrediction()

Create fitter with default parameters adapted for fitting pole parameters Xp and Yp for long term prediction.

The main difference between these settings and the settings for long prediction is the much smaller \(\tau\). This means more weight is set to the points at the end of the history, hence forcing the fitted prediction model to be closer to these points, hence the prediction error to be smaller just after raw history end. On the other hand, this implies that the model will diverge on long term. These settings are intended when prediction is used for at most 5 days after raw EOP end.

• time constant \(\tau\) of the exponential decay set to 12 days
• convergence set to 10⁻¹² rad
• polynomial part set to degree 3
• one harmonic term at SUN_PULSATION}
• one harmonic term at 2 times SUN_PULSATION}
• one harmonic term at 3 times SUN_PULSATION}
• one harmonic term at MOON_DRACONIC_PULSATION}
• one harmonic term at 2 times MOON_DRACONIC_PULSATION}
• one harmonic term at 3 times MOON_DRACONIC_PULSATION}

Returns:

fitter with default configuration for pole parameters Xp and Yp

createDefaultPoleFitterLongTermPrediction

public static SingleParameterFitter createDefaultPoleFitterLongTermPrediction()

Create fitter with default parameters adapted for fitting pole parameters Xp and Yp for long term prediction.

The main difference between these settings and the settings for short prediction is the much larger \(\tau\). This means weight is spread throughout history, hence forcing the fitted prediction model to be remain very stable on the long term. On the other hand, this implies that the model will start with already a much larger error just after raw history end. These settings are intended when prediction is used for 5 days after raw EOP end or more.

• time constant \(\tau\) of the exponential decay set to 60 days
• convergence set to 10⁻¹² rad
• polynomial part set to degree 3
• one harmonic term at SUN_PULSATION}
• one harmonic term at 2 times SUN_PULSATION}
• one harmonic term at 3 times SUN_PULSATION}
• one harmonic term at MOON_DRACONIC_PULSATION}
• one harmonic term at 2 times MOON_DRACONIC_PULSATION}
• one harmonic term at 3 times MOON_DRACONIC_PULSATION}

Returns:

fitter with default configuration for pole parameters Xp and Yp

createDefaultNutationFitterShortTermPrediction

public static SingleParameterFitter createDefaultNutationFitterShortTermPrediction()

Create fitter with default parameters adapted for fitting nutation parameters dx and dy for long term prediction.

The main difference between these settings and the settings for long prediction is the much smaller \(\tau\). This means more weight is set to the points at the end of the history, hence forcing the fitted prediction model to be closer to these points, hence the prediction error to be smaller just after raw history end. On the other hand, this implies that the model will diverge on long term. These settings are intended when prediction is used for at most 5 days after raw EOP end.

• time constant \(\tau\) of the exponential decay set to 12 days
• convergence set to 10⁻¹² s
• polynomial part set to degree 3
• one harmonic term at SUN_PULSATION}
• one harmonic term at 2 times SUN_PULSATION}
• one harmonic term at 3 times SUN_PULSATION}
• one harmonic term at MOON_DRACONIC_PULSATION}
• one harmonic term at 2 times MOON_DRACONIC_PULSATION}
• one harmonic term at 3 times MOON_DRACONIC_PULSATION}

Returns:

fitter with default configuration for pole nutation parameters dx and dy

createDefaultNutationFitterLongTermPrediction

public static SingleParameterFitter createDefaultNutationFitterLongTermPrediction()

Create fitter with default parameters adapted for fitting nutation parameters dx and dy for long term prediction.

The main difference between these settings and the settings for short prediction is the much larger \(\tau\). This means weight is spread throughout history, hence forcing the fitted prediction model to be remain very stable on the long term. On the other hand, this implies that the model will start with already a much larger error just after raw history end. These settings are intended when prediction is used for 5 days after raw EOP end or more.

• time constant \(\tau\) of the exponential decay set to 60 days
• convergence set to 10⁻¹² s
• polynomial part set to degree 3
• one harmonic term at SUN_PULSATION}
• one harmonic term at 2 times SUN_PULSATION}
• one harmonic term at 3 times SUN_PULSATION}
• one harmonic term at MOON_DRACONIC_PULSATION}
• one harmonic term at 2 times MOON_DRACONIC_PULSATION}
• one harmonic term at 3 times MOON_DRACONIC_PULSATION}

Returns:

fitter with default configuration for pole nutation parameters dx and dy