uk.ac.starlink.ttools.func
Class Tilings

java.lang.Object
  extended by uk.ac.starlink.ttools.func.Tilings

public class Tilings
extends Object

Pixel tiling functions for the celestial sphere.

Since:
6 Dec 2007
Author:
Mark Taylor

Method Summary
static int healpixK(double pixelsize)
          Gives the HEALPix resolution parameter suitable for a given pixel size.
static long healpixNestIndex(int k, double ra, double dec)
          Gives the pixel index for a given sky position in the HEALPix NEST scheme.
static double healpixResolution(int k)
          Gives the approximate resolution in degrees for a given HEALPix resolution parameter k This k value is the logarithm to base 2 of the Nside parameter.
static long healpixRingIndex(int k, double ra, double dec)
          Gives the pixel index for a given sky position in the HEALPix RING scheme.
static long htmIndex(int level, double ra, double dec)
          Gives the HTM (Hierachical Triangular Mesh) pixel index for a given sky position.
static int htmLevel(double pixelsize)
          Gives the HTM level parameter suitable for a given pixel size.
static double htmResolution(int level)
          Gives the approximate resolution in degrees for a given HTM depth level.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Method Detail

htmIndex

public static long htmIndex(int level,
                            double ra,
                            double dec)
Gives the HTM (Hierachical Triangular Mesh) pixel index for a given sky position.

Parameters:
level - HTM level
ra - right ascension in degrees
dec - declination in degrees
Returns:
pixel index
See Also:
HTM web site

healpixNestIndex

public static long healpixNestIndex(int k,
                                    double ra,
                                    double dec)
Gives the pixel index for a given sky position in the HEALPix NEST scheme.

Parameters:
k - resolution parameter - log to base 2 of nside
ra - right ascension in degrees
dec - declination in degrees
Returns:
pixel index
See Also:
HEALPix web site

healpixRingIndex

public static long healpixRingIndex(int k,
                                    double ra,
                                    double dec)
Gives the pixel index for a given sky position in the HEALPix RING scheme.

Parameters:
k - resolution parameter - log to base 2 of nside
ra - right ascension in degrees
dec - declination in degrees
Returns:
pixel index
See Also:
HEALPix web site

healpixK

public static int healpixK(double pixelsize)
Gives the HEALPix resolution parameter suitable for a given pixel size. This k value is the logarithm to base 2 of the Nside parameter.

Parameters:
pixelsize - pixel size in degrees
Returns:
HEALPix resolution parameter k
See Also:
HEALPix web site

healpixResolution

public static double healpixResolution(int k)
Gives the approximate resolution in degrees for a given HEALPix resolution parameter k This k value is the logarithm to base 2 of the Nside parameter.

Parameters:
k - HEALPix resolution parameter k
Returns:
approximate angular resolution in degrees

htmLevel

public static int htmLevel(double pixelsize)
Gives the HTM level parameter suitable for a given pixel size.

Parameters:
pixelsize - required resolution in degrees
Returns:
HTM level parameter

htmResolution

public static double htmResolution(int level)
Gives the approximate resolution in degrees for a given HTM depth level.

Parameters:
level - HTM depth
Returns:
approximate angular resolution in degrees


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