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

Fields
Modifier and Type	Field and Description
`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

Constructors
Constructor and Description

Precesser()

Constructors
Constructor and Description
`Precesser()`

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static QuadMatrix`	`generalPrecession(double deq1, double deq2)` Returns the general precession matrix.
`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

Class Precesser

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

RAPREC

DRACEN

DEPREC

DDECEN

ZETA0

ZETA0T

ZETA0TT

ZETA1

ZETA1T

ZETA2

Z0

Z0T

Z0TT

Z1

Z1T

Z2

THETA0

THETA0T

THETA0TT

THETA1

THETA1T

THETA2

CLOSEPOLE

Constructor Detail

Precesser

Method Detail

precession

precessionMeeus

generalPrecession