agi.foundation.celestial

(agi.foundation.models-2024r2.jar)

Class IersTechnicalNote21

java.lang.Object

agi.foundation.celestial.IersTechnicalNote21

public final class IersTechnicalNote21
extends Object

Provides Earth orientation parameters according to the IERS Technical Note 21.

Method Summary

Modifier and Type	Method and Description
static double	getGreenwichHourAngle(JulianDate date) Computes the hour angle measured using the Greenwich mean sidereal time.
static double	getGreenwichMeanSiderealTime(JulianDate date) Computes the mean sidereal time of Greenwich at the provided Julian date.
static double	getGreenwichMeanSiderealTimeOfMidnight(JulianDate date) Computes the mean sidereal time of Greenwich at 0hr UT1 on the provided Julian date.
static MotionEvaluator1<Double>	getGreenwichTrueSiderealTimeEvaluator() Gets an evaluator that computes the true sidereal time of Greenwich.
static MotionEvaluator1<Double>	getGreenwichTrueSiderealTimeEvaluator(EvaluatorGroup group) Gets an evaluator that computes the true sidereal time of Greenwich.
static NutationModel	getUpdated1980NutationModel() Gets an instance of the nutation model published by the IERS in 1996 to modify the fundamental arguments of the IAU1980 Nutation theory.
static EquationOfEquinoxes	getUpdatedEquationOfEquinoxes() Gets an instance of the updated equation of the equinoxes published by the IERS in 1996.

Methods inherited from class java.lang.Object

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

Method Detail

getUpdated1980NutationModel

@Nonnull
public static NutationModel getUpdated1980NutationModel()

Gets an instance of the nutation model published by the IERS in 1996 to modify the fundamental arguments of the IAU1980 Nutation theory.

getUpdatedEquationOfEquinoxes

@Nonnull
public static EquationOfEquinoxes getUpdatedEquationOfEquinoxes()

Gets an instance of the updated equation of the equinoxes published by the IERS in 1996. The updated equation defines the right ascension of the mean equinox with respect to the true equator and equinox with the addition of periodic terms involving the right ascension of the moon.

getGreenwichMeanSiderealTimeOfMidnight

public static double getGreenwichMeanSiderealTimeOfMidnight(@Nonnull
                                                            JulianDate date)

Computes the mean sidereal time of Greenwich at 0hr UT1 on the provided Julian date.

Parameters:

date - The date at which to retrieve the mean sidereal time

Returns:

The mean sidereal time of Greenwich at 0hr UT1, in seconds.

getGreenwichMeanSiderealTime

public static double getGreenwichMeanSiderealTime(@Nonnull
                                                  JulianDate date)

Computes the mean sidereal time of Greenwich at the provided Julian date.

Parameters:

date - The date at which to retrieve the mean sidereal time

Returns:

The mean sidereal time of Greenwich, in seconds.

getGreenwichHourAngle

public static double getGreenwichHourAngle(@Nonnull
                                           JulianDate date)

Computes the hour angle measured using the Greenwich mean sidereal time.

Parameters:

date - The date at which to retrieve the hour angle.

Returns:

The Greenwich hour angle (GHA), in radians.

getGreenwichTrueSiderealTimeEvaluator

@Nonnull
public static MotionEvaluator1<Double> getGreenwichTrueSiderealTimeEvaluator()

Gets an evaluator that computes the true sidereal time of Greenwich.

The result of evaluating will be a Motion<double> which represents the value of the Greenwich true sidereal time in seconds at the given JulianDate. No derivatives are provided.

Returns:

An evaluator that computes the true sidereal time of Greenwich

getGreenwichTrueSiderealTimeEvaluator

@Nonnull
public static MotionEvaluator1<Double> getGreenwichTrueSiderealTimeEvaluator(@Nonnull
                                                                                       EvaluatorGroup group)

Gets an evaluator that computes the true sidereal time of Greenwich.

The result of evaluating will be a Motion<double> which represents the value of the Greenwich true sidereal time in seconds at the given JulianDate. No derivatives are provided.

Parameters:

group - The group with which to associate the new evaluator. By grouping evaluators that are often evaluated at the same Julian dates, common computations can be performed only once for the entire group instead of multiple times for each evaluator.

Returns:

An evaluator that computes the true sidereal time of Greenwich