uk.ac.starlink.ttools.convert

Class SkySystem

java.lang.Object

uk.ac.starlink.ttools.convert.SkySystem

public abstract class SkySystem
extends Object

Represents a sky coordinate system.

Conversions all go via FK5 J2000.0, I think. SLALIB (Pal) is used to do the work. In some cases an epoch is considered. No opportunity is given for using an equinox value. I am not an expert on sky coordinate systems, and I think there may be subtleties which I'm not addressing accurately here.

Since:

30 Aug 2005

Author:

Mark Taylor

Field Summary

Fields

Modifier and Type	Field and Description
static SkySystem	ECLIPTIC Ecliptic sysem.
static SkySystem	FK4 FK4 system.
static SkySystem	FK5 FK5 system.
static SkySystem	GALACTIC Galactic system.
static SkySystem	ICRS ICRS system.
static SkySystem	SUPERGALACTIC Supergalactic system.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	SkySystem(String name, String description, String ucd1, String ucd2, String descrip1, String descrip2, String colname1, String colname2) Constructor.

Method Summary

Modifier and Type	Method and Description
abstract double[]	fromFK5(double c1, double c2, double epoch) Converts from FK5 J2000.0 into this system.
String[]	getCoordinateColumnNames() Returns labels suitable for use as column names in this system.
String[]	getCoordinateDescriptions() Returns a full description of each coordinate in this system.
String[]	getCoordinateNames() Returns names of the coordinates in this system.
String[]	getCoordinateUcds() Returns a suitable UCD1+ for each coordinate in this system.
String	getDescription() Returns a short description of this system.
static SkySystem[]	getKnownSystems() Returns an array of all the systems known.
String	getName() Returns the name of this system.
static SkySystem	getSystemFor(String sysName) Returns a system which matches a given string.
static String	getSystemUsage() Returns a snippet of XML which describes the systems and their meanings.
abstract double[]	toFK5(double c1, double c2, double epoch) Converts to FK5 J2000.0 from this system.
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

ICRS

public static final SkySystem ICRS

ICRS system.

FK5

public static final SkySystem FK5

FK5 system.

FK4

public static final SkySystem FK4

FK4 system.

GALACTIC

public static final SkySystem GALACTIC

Galactic system.

SUPERGALACTIC

public static final SkySystem SUPERGALACTIC

Supergalactic system.

ECLIPTIC

public static final SkySystem ECLIPTIC

Ecliptic sysem.

Constructor Detail

SkySystem

protected SkySystem(String name,
                    String description,
                    String ucd1,
                    String ucd2,
                    String descrip1,
                    String descrip2,
                    String colname1,
                    String colname2)

Constructor.

Parameters:

name - short system name

description - a few words of description

ucd1 - UCD1+ for first coordinate

ucd2 - UCD1+ for second coordinate

descrip1 - short description of first coordinate

descrip2 - short description of second coordinate

colname1 - label for first coordinate suitable for use as column name

colname2 - label for second coordinate suitable for use as column name

Method Detail

fromFK5

public abstract double[] fromFK5(double c1,
                                 double c2,
                                 double epoch)

Converts from FK5 J2000.0 into this system.

Parameters:

c1 - right ascension in FK5 (radians)

c2 - declination in FK5 (radians)

Returns:

2-element array of coordinates in this system (radians)

toFK5

public abstract double[] toFK5(double c1,
                               double c2,
                               double epoch)

Converts to FK5 J2000.0 from this system.

Parameters:

c1 - first coordinate in this system (radians)

c2 - second coordinate in this system (radians)

Returns:

2-element array containing (RA, Dec) in FK5 (radians)

getName

public String getName()

Returns the name of this system.

Returns:

system name

getDescription

public String getDescription()

Returns a short description of this system.

Returns:

system description

getCoordinateUcds

public String[] getCoordinateUcds()

Returns a suitable UCD1+ for each coordinate in this system.

Returns:

2-element array of coordinate UCDs

getCoordinateDescriptions

public String[] getCoordinateDescriptions()

Returns a full description of each coordinate in this system.

Returns:

array of coordinate descriptions

getCoordinateNames

public String[] getCoordinateNames()

Returns names of the coordinates in this system.

Returns:

array of coordinate names

getCoordinateColumnNames

public String[] getCoordinateColumnNames()

Returns labels suitable for use as column names in this system.

Returns:

array of column names

toString

public String toString()

Overrides:

toString in class Object

getKnownSystems

public static SkySystem[] getKnownSystems()

Returns an array of all the systems known.

Returns:

system array

getSystemUsage

public static String getSystemUsage()

Returns a snippet of XML which describes the systems and their meanings.

Returns:

XML description of this class and its instances

getSystemFor

public static SkySystem getSystemFor(String sysName)

Returns a system which matches a given string. Abbreviations may be used.

Parameters:

sysName - name to match

Returns:

a SkySystem, not null

Throws:

IllegalArgumentException - if sysName isn't a system name