jephem.astro
Class MeanTrue

java.lang.Object
  |
  +--jephem.astro.MeanTrue

All Implemented Interfaces:

TimeConstants

public class MeanTrue

extends java.lang.Object

implements TimeConstants

An object of this class holds data permitting to handle conversions between mean and true coordinates.
This class was written from a BDL theory which can be found at ftp://ftp.bdl.fr/pub/ephem/ref-frames/prcbld94 ; see also "Numerical expressions for precession formulae and mean elements for the Moon and the planets" from Astron. Astrophys. 282, 663 (1994).

Field Summary

static int	QTY_chi_a Constant to access ca precession quantity (value = 11).
static int	QTY_deltaEpsilon Constant to access De precession quantity (value = 13).
static int	QTY_deltaPsi Constant to access Dy nutation quantity (value = 12).
static int	QTY_epsilon_a Constant to access ea precession quantity (value = 8).
static int	QTY_omega_a Constant to access Wa precession quantity (value = 9).
static int	QTY_P_a Constant to access Pa precession quantity (value = 4).
static int	QTY_pi_a Constant to access pa precession quantity (value = 2).
static int	QTY_PI_a Constant to access Pa precession quantity (value = 3).
static int	QTY_psi_a Constant to access ya precession quantity (value = 10).
static int	QTY_sc_a Constant to access sin(pa)cos(Pa) precession quantity (value = 1).
static int	QTY_ss_a Constant to access sin(pa)sin(Pa) precession quantity (value = 0).
static int	QTY_theta_a Constant to access qa precession quantity (value = 5).
static int	QTY_z_a Constant to access za precession quantity (value = 7).
static int	QTY_zeta_a Constant to access za precession quantity (value = 6).

Fields inherited from interface jephem.astro.spacetime.TimeConstants

DAYS_PER_CENTURY, DAYS_PER_MILLENIUM, DAYS_PER_YEAR, JD1900, JD2000, JD2100, SECONDS_PER_DAY, TT_TDB, UTC

Constructor Summary

MeanTrue(double date, double fixedEpoch)
Unique constructor.

Method Summary

Matrix3	getEqNutationMatrix() Returns the nutation matrix permitting to transform from mean equatorial coordinates of a date to true equatorial coordinates of a date.
Matrix3	getEqPrecessionMatrix() Returns the precession matrix permitting to transform from mean equatorial coordinates of the fixedEpoch to mean equatorial coordinates of the date.
double	getQuantity(int index) Returns a quantity (precession or nutation), expressed in arc seconds.
Matrix3	getTrueEqToEcMatrix() Returns the nutation matrix permitting to transform from mean equatorial coordinates of a date to true equatorial coordinates of a date.

Methods inherited from class java.lang.Object

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

Field Detail

QTY_chi_a

public static final int QTY_chi_a

Constant to access ca precession quantity (value = 11).

See Also:

Constant Field Values

QTY_deltaEpsilon

public static final int QTY_deltaEpsilon

Constant to access De precession quantity (value = 13).

See Also:

Constant Field Values

QTY_deltaPsi

public static final int QTY_deltaPsi

Constant to access Dy nutation quantity (value = 12).

See Also:

Constant Field Values

QTY_epsilon_a

public static final int QTY_epsilon_a

Constant to access ea precession quantity (value = 8).

See Also:

Constant Field Values

QTY_omega_a

public static final int QTY_omega_a

Constant to access Wa precession quantity (value = 9).

See Also:

Constant Field Values

QTY_P_a

public static final int QTY_P_a

Constant to access Pa precession quantity (value = 4).

See Also:

Constant Field Values

QTY_pi_a

public static final int QTY_pi_a

Constant to access pa precession quantity (value = 2).

See Also:

Constant Field Values

QTY_PI_a

public static final int QTY_PI_a

Constant to access Pa precession quantity (value = 3).

See Also:

Constant Field Values

QTY_psi_a

public static final int QTY_psi_a

Constant to access ya precession quantity (value = 10).

See Also:

Constant Field Values

QTY_sc_a

public static final int QTY_sc_a

Constant to access sin(pa)cos(Pa) precession quantity (value = 1).

See Also:

Constant Field Values

QTY_ss_a

public static final int QTY_ss_a

Constant to access sin(pa)sin(Pa) precession quantity (value = 0).

See Also:

Constant Field Values

QTY_theta_a

public static final int QTY_theta_a

Constant to access qa precession quantity (value = 5).

See Also:

Constant Field Values

QTY_z_a

public static final int QTY_z_a

Constant to access za precession quantity (value = 7).

See Also:

Constant Field Values

QTY_zeta_a

public static final int QTY_zeta_a

Constant to access za precession quantity (value = 6).

See Also:

Constant Field Values

Constructor Detail

MeanTrue

public MeanTrue(double date,
                double fixedEpoch)

Unique constructor.

Parameters:

date - the date expressed in julian days.

fixedEpoch - the fixed epoch expressed in julian days.

Method Detail

getEqNutationMatrix

public Matrix3 getEqNutationMatrix()

Returns the nutation matrix permitting to transform from mean equatorial coordinates of a date to true equatorial coordinates of a date.

getEqPrecessionMatrix

public Matrix3 getEqPrecessionMatrix()

Returns the precession matrix permitting to transform from mean equatorial coordinates of the fixedEpoch to mean equatorial coordinates of the date.

getQuantity

public double getQuantity(int index)

Returns a quantity (precession or nutation), expressed in arc seconds.
The precession quantities are computed using the 1992 IERS planetary masses.

Parameters:

index - index used to specify which quantity to return ; use the QTY_xxx constants of this class to express 'index'

getTrueEqToEcMatrix

public Matrix3 getTrueEqToEcMatrix()

Returns the nutation matrix permitting to transform from mean equatorial coordinates of a date to true equatorial coordinates of a date.