org.britastro.grelf.astro

Class Epoch

java.lang.Object

org.britastro.grelf.astro.Epoch

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable

public class Epoch
extends java.lang.Object
implements java.lang.Cloneable, java.io.Serializable

Represent astronomical epochs, such as B1950.0 or J2010.0. The IAU changed the standard from Besselian to Julian as from 1984. Besselian epochs use tropical years of 365.2421988 days. The Julian system is in some ways simpler because it uses years of exactly 365.25 days. Epoch B1950.0 was JDE 2433282.4235. Epoch J2000.0 was JDE 2451545.0 exactly.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static Epoch	B1950
static Epoch	J2000

Constructor Summary

Constructors

Constructor and Description
Epoch(char type, float year) Creates an Epoch with any type letter (but it must be 'B' or 'J' to make sense astronomically).
Epoch(float year) Creates an Epoch assuming the type letter is 'J'.

Method Summary

Methods

Modifier and Type	Method and Description
Epoch	clone()
boolean	equals(java.lang.Object other)
JulianDate	getJulianDate() Returns null if the epoch type is not 'B' or 'J'.
char	getType() 'J' or 'B'.
float	getYear()
int	hashCode() Enable objects of this class to be used as hash keys.
java.lang.String	toString()

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

J2000

public static Epoch J2000

B1950

public static Epoch B1950

Constructor Detail

Epoch

public Epoch(float year)

Creates an Epoch assuming the type letter is 'J'.

Epoch

public Epoch(char type,
     float year)

Creates an Epoch with any type letter (but it must be 'B' or 'J' to make sense astronomically).

Method Detail

getYear

public float getYear()

getType

public char getType()

'J' or 'B'.

getJulianDate

public JulianDate getJulianDate()

Returns null if the epoch type is not 'B' or 'J'.

equals

public boolean equals(java.lang.Object other)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Enable objects of this class to be used as hash keys.

Overrides:

hashCode in class java.lang.Object

clone

public Epoch clone()

Overrides:

clone in class java.lang.Object

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object