agi.foundation.celestial

(agi.foundation.models-2025r1.jar)

Class EarthOrientationParameters

java.lang.Object

agi.foundation.celestial.EarthOrientationParameters

All Implemented Interfaces:

IEquatableDefinition

public class EarthOrientationParameters
extends Object
implements IEquatableDefinition

Specifies Earth polar motion coordinates and the difference between UT1 and UTC.

In order to do their work, many other classes require that the OrientationParameters (get / set) property of the Earth (get) instance in the CentralBodiesFacet calculation context facet hold a valid instance of this class. You can obtain an EOP data file from https://ftp.agi.com/pub/DynamicEarthData/EOP-v1.1.txt and read it using EarthOrientationParametersFile.

This example shows how to load EOP data from a file and add it to the current calculation context:

EarthOrientationParameters eop = EarthOrientationParametersFile.readData(new File(dataPath, "EOP-v1.1.txt").getPath());
CentralBodiesFacet.getFromContext().getEarth().setOrientationParameters(eop);

This example shows how to download EOP data over the internet from an AGI server, and add it to the current calculation context:

CentralBodiesFacet.getFromContext().getEarth().setOrientationParameters(EarthOrientationParametersFile.downloadData());

Constructor Summary

Constructors

Constructor and Description
EarthOrientationParameters() Initializes a new instance with no pole wander and no difference between UT1 and UTC.
EarthOrientationParameters(Iterable<? extends EarthOrientationParametersData> data) Initializes a new instance from the specified list of data points.
EarthOrientationParameters(Iterable<? extends EarthOrientationParametersData> data, TimeInterval observedInterval, TimeInterval predictedInterval, Iterable<LeapSecond> leapSeconds) Initializes a new instance from the specified list of data points.
EarthOrientationParameters(Iterable<? extends EarthOrientationParametersData> data, TimeInterval observedInterval, TimeInterval predictedInterval, Iterable<LeapSecond> leapSeconds, String nativeItrfFrame) Initializes a new instance from the specified list of data points.

Method Summary

Modifier and Type	Method and Description
Rectangular	computeCelestialPoleOffset(JulianDate date) Finds the offset to the Celestial Intermediate Pole (CIP) for the given date by interpolating this EOP data, in arc seconds.
double	computeDeltaEpsilonCorrection(JulianDate date) Finds the correction to the nutation in obliquity (delta Delta epsilon), in arc seconds, for the given date by interpolating this EOP data.
double	computeDeltaPsiCorrection(JulianDate date) Finds the correction to the nutation in longitude (delta Delta psi), in arc seconds, for the given date by interpolating this EOP data.
EarthOrientationParametersData	computeEopData(JulianDate date) Creates an EarthOrientationParametersData object with the given date and information from the various Compute methods such as EarthOrientationParameters.computePoleWander(agi.foundation.time.JulianDate).
double	computeLengthOfDayCorrection(JulianDate date) Finds the correction to the length of a solar day (86400.0 sec) for the given date by interpolating this EOP data.
Rectangular	computePoleWander(JulianDate date) Finds the pole wander for the given date by interpolating this EOP data, in arc seconds.
double	computeTaiMinusUtc(JulianDate date) Returns the difference TAI - UTC for the given date by returning the number of leap seconds at the previous data point.
double	computeUt1MinusUtc(JulianDate date) Returns the difference UT1 - UTC for the given date by interpolating this EOP data.
List<EarthOrientationParametersData>	getData() Gets the EOP data represented by this instance.
int	getDefinitionHashCode() Gets a hash code representing the definition of this object.
List<LeapSecond>	getLeapSeconds() Gets a list of leap seconds, if known, indicating times when a data point indicates a delta between TAI and UTC which differs from the prior data point.
String	getNativeItrfFrame() Gets the native International Terrestrial Reference Frame (ITRF) associated with these parameters.
TimeInterval	getObservedInterval() Gets the time interval of observed data points, if known.
TimeInterval	getPredictedInterval() Gets the time interval of predicted data points, if known.
boolean	isSameDefinition(Object other) Determines if this object has the same definition as another object.
static void	useForTimeStandardConversions() Configures the TimeStandardConverter so that EOP data is used to convert between the UTC and UT1 time standards.

Methods inherited from class java.lang.Object

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

Constructor Detail

EarthOrientationParameters

public EarthOrientationParameters()

Initializes a new instance with no pole wander and no difference between UT1 and UTC.

EarthOrientationParameters

public EarthOrientationParameters(@Nonnull
                                  Iterable<? extends EarthOrientationParametersData> data)

Initializes a new instance from the specified list of data points.

Parameters:

data - The list of EOP data points.

EarthOrientationParameters

public EarthOrientationParameters(@Nonnull
                                  Iterable<? extends EarthOrientationParametersData> data,
                                  TimeInterval observedInterval,
                                  TimeInterval predictedInterval,
                                  @Nonnull
                                  Iterable<LeapSecond> leapSeconds)

Initializes a new instance from the specified list of data points.

Parameters:

data - The list of EOP data points.

observedInterval - The time interval of observed data points.

predictedInterval - The time interval of predicted data points.

leapSeconds - A list of leap second objects indicating times when the delta between TAI and UTC differs from the previous data point.

EarthOrientationParameters

public EarthOrientationParameters(@Nonnull
                                  Iterable<? extends EarthOrientationParametersData> data,
                                  TimeInterval observedInterval,
                                  TimeInterval predictedInterval,
                                  @Nonnull
                                  Iterable<LeapSecond> leapSeconds,
                                  @Nonnull
                                  String nativeItrfFrame)

Initializes a new instance from the specified list of data points.

Parameters:

data - The list of EOP data points.

observedInterval - The time interval of observed data points.

predictedInterval - The time interval of predicted data points.

leapSeconds - A list of leap second objects indicating times when the delta between TAI and UTC differs from the previous data point.

nativeItrfFrame - The native International Terrestrial Reference Frame (ITRF) associated with these parameters.

Method Detail

isSameDefinition

public final boolean isSameDefinition(Object other)

Determines if this object has the same definition as another object.

This method is very similar to Object.equals(Object) except that it explicitly considers the "definitions" of the two objects for objects that do not typically act like values. The definition of an object typically includes all of the fields of the object.

Specified by:

isSameDefinition in interface IEquatableDefinition

Parameters:

other - The other instance to compare to this one.

Returns:

true if this object has the same definition as the specified one. false if the other object is null, a different type than this one, or if this object and the specified one have different definitions.

getDefinitionHashCode

public final int getDefinitionHashCode()

Gets a hash code representing the definition of this object.

This method is very similar to Object.hashCode() except that it explicitly includes the "definition" of the object even if the object does not typically act like a value. The definition of an object typically includes all of the fields of the object. The value returned by this method should NOT change. This means that two objects for which EarthOrientationParameters.isSameDefinition(java.lang.Object) returns true will not necessarily have the same hash code if one or the other was changed after the hash code was first obtained.

Specified by:

getDefinitionHashCode in interface IEquatableDefinition

Returns:

The hash code.

getData

@Nonnull
public final List<EarthOrientationParametersData> getData()

Gets the EOP data represented by this instance.

getObservedInterval

public final TimeInterval getObservedInterval()

Gets the time interval of observed data points, if known.

getPredictedInterval

public final TimeInterval getPredictedInterval()

Gets the time interval of predicted data points, if known.

getLeapSeconds

@Nonnull
public final List<LeapSecond> getLeapSeconds()

Gets a list of leap seconds, if known, indicating times when a data point indicates a delta between TAI and UTC which differs from the prior data point. Note that this may not be a complete or accurate set of leap seconds, since it only includes those that occurred during the time period covered by a particular EOP file.

getNativeItrfFrame

public final String getNativeItrfFrame()

Gets the native International Terrestrial Reference Frame (ITRF) associated with these parameters.

computeUt1MinusUtc

public final double computeUt1MinusUtc(@Nonnull
                                       JulianDate date)

Returns the difference UT1 - UTC for the given date by interpolating this EOP data.

Parameters:

date - The date.

Returns:

The difference in seconds.

computeTaiMinusUtc

public final double computeTaiMinusUtc(@Nonnull
                                       JulianDate date)

Returns the difference TAI - UTC for the given date by returning the number of leap seconds at the previous data point.

Parameters:

date - The date.

Returns:

The difference in seconds.

computePoleWander

@Nonnull
public final Rectangular computePoleWander(@Nonnull
                                                     JulianDate date)

Finds the pole wander for the given date by interpolating this EOP data, in arc seconds.

Parameters:

date - The date at which to retrieve pole wander information.

Returns:

The wander of the pole for the given date.

computeCelestialPoleOffset

@Nonnull
public final Rectangular computeCelestialPoleOffset(@Nonnull
                                                              JulianDate date)

Finds the offset to the Celestial Intermediate Pole (CIP) for the given date by interpolating this EOP data, in arc seconds.

Parameters:

date - The date at which to retrieve the celestial pole offset.

Returns:

The offset to the celestial intermediate pole, in arc seconds.

computeLengthOfDayCorrection

public final double computeLengthOfDayCorrection(@Nonnull
                                                 JulianDate date)

Finds the correction to the length of a solar day (86400.0 sec) for the given date by interpolating this EOP data.

Parameters:

date - The date at which to retrieve the length of day correction.

Returns:

The length of day correction, in seconds.

computeDeltaPsiCorrection

public final double computeDeltaPsiCorrection(@Nonnull
                                              JulianDate date)

Finds the correction to the nutation in longitude (delta Delta psi), in arc seconds, for the given date by interpolating this EOP data.

This correction corresponds to the IAU1980 nutation theory.

Parameters:

date - The date at which to retrieve the delta psi correction.

Returns:

The correction to the nutation in longitude, in arc seconds.

computeDeltaEpsilonCorrection

public final double computeDeltaEpsilonCorrection(@Nonnull
                                                  JulianDate date)

Finds the correction to the nutation in obliquity (delta Delta epsilon), in arc seconds, for the given date by interpolating this EOP data.

This correction corresponds to the IAU1980 nutation theory.

Parameters:

date - The date at which to retrieve the delta psi correction.

Returns:

The correction to the nutation in longitude, in arc seconds.

computeEopData

@Nonnull
public final EarthOrientationParametersData computeEopData(@Nonnull
                                                                     JulianDate date)

Creates an EarthOrientationParametersData object with the given date and information from the various Compute methods such as EarthOrientationParameters.computePoleWander(agi.foundation.time.JulianDate).

Parameters:

date - The date

Returns:

The Earth Orientation Parameters data.

useForTimeStandardConversions

public static void useForTimeStandardConversions()

Configures the TimeStandardConverter so that EOP data is used to convert between the UTC and UT1 time standards.