astro
Class Precesser

java.lang.Object
  astro.Precesser

public class Precesser
extends Object

Class to do a simple precession. Future versions may include more precise versions.

Field Summary

private static double	CLOSEPOLE The sin of a declination considered close to pole.
static double	DDECEN Precession change in de, arcsec/100y.
static double	DEPREC Precession constant in de, arcsec/y.
static double	DRACEN Precession change in ra, arcsec/100y.
static double	RAPREC Precession constant in ra, arcsec/y.
static double	THETA0 Precession constant theta, arcsec.
static double	THETA0T Precession constant theta, arcsec.
static double	THETA0TT Precession constant theta, arcsec.
static double	THETA1 Precession constant theta, arcsec.
static double	THETA1T Precession constant theta, arcsec.
static double	THETA2 Precession constant theta, arcsec.
static double	Z0 Precession constant z, arcsec.
static double	Z0T Precession constant z, arcsec.
static double	Z0TT Precession constant z, arcsec.
static double	Z1 Precession constant z, arcsec.
static double	Z1T Precession constant z, arcsec.
static double	Z2 Precession constant z, arcsec.
static double	ZETA0 Precession constant zeta, arcsec.
static double	ZETA0T Precession constant zeta, arcsec.
static double	ZETA0TT Precession constant zeta, arcsec.
static double	ZETA1 Precession constant zeta, arcsec.
static double	ZETA1T Precession constant zeta, arcsec.
static double	ZETA2 Precession constant z, arcsec.

Constructor Summary

Precesser()

Method Summary

static QuadMatrix	generalPrecession(double deq1, double deq2) Returns the general precession matrix.
static void	main(String[] arg) Test precession, simple vs.
static Vector2D	precession(double ra, double dec, double oldyear, double newyear) Calculate (simple) precession to new epoch (year).
static Vector2D	precessionMeeus(double ra, double de, double jd0, double jdnew) Uses a more precise formular, given by J.Meeus, Astronomical Algorithms, eq.

Methods inherited from class java.lang.Object

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

Field Detail

RAPREC

public static final double RAPREC

Precession constant in ra, arcsec/y.

See Also:

Constant Field Values

DRACEN

public static final double DRACEN

Precession change in ra, arcsec/100y.

See Also:

Constant Field Values

DEPREC

public static final double DEPREC

Precession constant in de, arcsec/y.

See Also:

Constant Field Values

DDECEN

public static final double DDECEN

Precession change in de, arcsec/100y.

See Also:

Constant Field Values

ZETA0

public static final double ZETA0

Precession constant zeta, arcsec.

See Also:

Constant Field Values

ZETA0T

public static final double ZETA0T

Precession constant zeta, arcsec.

See Also:

Constant Field Values

ZETA0TT

public static final double ZETA0TT

Precession constant zeta, arcsec.

See Also:

Constant Field Values

ZETA1

public static final double ZETA1

Precession constant zeta, arcsec.

See Also:

Constant Field Values

ZETA1T

public static final double ZETA1T

Precession constant zeta, arcsec.

See Also:

Constant Field Values

ZETA2

public static final double ZETA2

Precession constant z, arcsec.

See Also:

Constant Field Values

Z0

public static final double Z0

Precession constant z, arcsec.

See Also:

Constant Field Values

Z0T

public static final double Z0T

Precession constant z, arcsec.

See Also:

Constant Field Values

Z0TT

public static final double Z0TT

Precession constant z, arcsec.

See Also:

Constant Field Values

Z1

public static final double Z1

Precession constant z, arcsec.

See Also:

Constant Field Values

Z1T

public static final double Z1T

Precession constant z, arcsec.

See Also:

Constant Field Values

Z2

public static final double Z2

Precession constant z, arcsec.

See Also:

Constant Field Values

THETA0

public static final double THETA0

Precession constant theta, arcsec.

See Also:

Constant Field Values

THETA0T

public static final double THETA0T

Precession constant theta, arcsec.

See Also:

Constant Field Values

THETA0TT

public static final double THETA0TT

Precession constant theta, arcsec.

See Also:

Constant Field Values

THETA1

public static final double THETA1

Precession constant theta, arcsec.

See Also:

Constant Field Values

THETA1T

public static final double THETA1T

Precession constant theta, arcsec.

See Also:

Constant Field Values

THETA2

public static final double THETA2

Precession constant theta, arcsec.

See Also:

Constant Field Values

CLOSEPOLE

private static final double CLOSEPOLE

The sin of a declination considered close to pole.

See Also:

Constant Field Values

Constructor Detail

Precesser

public Precesser()

Method Detail

precession

public static Vector2D precession(double ra,
                                  double dec,
                                  double oldyear,
                                  double newyear)

Calculate (simple) precession to new epoch (year). ra, dec are in radians.

Parameters:

ra - Right ascension in old epoch

dec - Declination in old epoch

oldjd - Old epoch in years, e.g. 2000.0

newjd - New epoch in years, e.g. 1950.0

Returns:

a vector, first coordinate ra, second de in new epoch

precessionMeeus

public static Vector2D precessionMeeus(double ra,
                                       double de,
                                       double jd0,
                                       double jdnew)

Uses a more precise formular, given by J.Meeus, Astronomical Algorithms, eq. 20.2. Position is in radians, epoch in JD.

generalPrecession

public static QuadMatrix generalPrecession(double deq1,
                                           double deq2)

Returns the general precession matrix. Based on fortran code by P. STUMPFF (IBM-VERSION 1979): ASTRON. ASTROPHYS. SUPPL. SER. 41, 1 (1980).

Parameters:

deq1 - Equinox (years like 1950) from

deq2 - Equinox (years like 1950) to

Returns:

3x3 Matrix

main

public static void main(String[] arg)

Test precession, simple vs. Meeus.