Tilings (Starlink-UK API)

java.lang.Object
- uk.ac.starlink.ttools.func.Tilings

```
public class Tilings
extends Object
```
Pixel tiling functions for the celestial sphere.
The k parameter for the HEALPix functions is the HEALPix order, which can be in the range 0<=k<=29. This is the logarithm to base 2 of the HEALPix NSIDE parameter. At order k, there are 12*4^k pixels on the sphere.

Since:

6 Dec 2007

Author:

Mark Taylor

See Also:

HTM web site, HEALPix web site

Field Summary

Fields
Modifier and Type Field and Description

static double SQDEG
Solid angle in steradians corresponding to 1 square degree.

Fields
Modifier and Type	Field and Description
`static double`	`SQDEG` Solid angle in steradians corresponding to 1 square degree.

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static int`	`healpixK(double pixelsize)` Gives the HEALPix resolution parameter suitable for a given pixel size.
`static long`	`healpixNestIndex(int k, double lon, double lat)` Gives the pixel index for a given sky position in the HEALPix NEST scheme.
`static double`	`healpixNestLat(int k, long index)` Returns the latitude of the approximate center of the tile with a given index in the HEALPix NEST scheme.
`static double`	`healpixNestLon(int k, long index)` Returns the longitude of the approximate center of the tile with a given index in the HEALPix NEST scheme.
`static long`	`healpixNestToRing(int k, long nestIndex)` Converts a healpix tile index from the NEST to the RING scheme at a given order.
`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 lon, double lat)` Gives the pixel index for a given sky position in the HEALPix RING scheme.
`static double`	`healpixRingLat(int k, long index)` Returns the latitude of the approximate center of the tile with a given index in the HEALPix RING scheme.
`static double`	`healpixRingLon(int k, long index)` Returns the longitude of the approximate center of the tile with a given index in the HEALPix RING scheme.
`static long`	`healpixRingToNest(int k, long ringIndex)` Converts a healpix tile index from the RING to the NEST scheme at a given order.
`static double`	`healpixSqdeg(int k)` Returns the solid angle in square degrees of each HEALPix pixel at a given order.
`static double`	`healpixSteradians(int k)` Returns the solid angle in steradians of each HEALPix pixel at a given order.
`static long`	`htmIndex(int level, double lon, double lat)` 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.
`static double`	`sqdegToSteradians(double sqdeg)` Converts a solid angle from square degrees to steradians.
`static double`	`steradiansToSqdeg(double sr)` Converts a solid angle from steradians to square degrees.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - SQDEG
```
public static final double SQDEG
```
    Solid angle in steradians corresponding to 1 square degree.
    
    See Also:
    
    Constant Field Values
- Method Detail
  - htmIndex
```
public static long htmIndex(int level,
                            double lon,
                            double lat)
```
    Gives the HTM (Hierachical Triangular Mesh) pixel index for a given sky position.
    
    Parameters:
    
    level - HTM level
    
    lon - longitude in degrees
    
    lat - latitude in degrees
    
    Returns:
    
    pixel index
    
    See Also:
    
    HTM web site
  - healpixNestIndex
```
public static long healpixNestIndex(int k,
                                    double lon,
                                    double lat)
```
    Gives the pixel index for a given sky position in the HEALPix NEST scheme.
    
    Parameters:
    
    k - HEALPix order (0..29)
    
    lon - longitude in degrees
    
    lat - latitude in degrees
    
    Returns:
    
    pixel index
    
    See Also:
    
    HEALPix web site
  - healpixRingIndex
```
public static long healpixRingIndex(int k,
                                    double lon,
                                    double lat)
```
    Gives the pixel index for a given sky position in the HEALPix RING scheme.
    
    Parameters:
    
    k - HEALPix order (0..29)
    
    lon - longitude in degrees
    
    lat - latitude in degrees
    
    Returns:
    
    pixel index
    
    See Also:
    
    HEALPix web site
  - healpixNestLon
```
public static double healpixNestLon(int k,
                                    long index)
```
    Returns the longitude of the approximate center of the tile with a given index in the HEALPix NEST scheme.
    Note: the index parameter is 0-based, unlike the table row index special token $index (a.k.a. $0), which is 1-based. So if the HEALpix index is implicitly determined by the table row, the value $index-1 should be used.
    
    Parameters:
    
    k - HEALPix order (0..29)
    
    index - healpix index
    
    Returns:
    
    longitude in degrees
    
    See Also:
    
    HEALPix web site
  - healpixNestLat
```
public static double healpixNestLat(int k,
                                    long index)
```
    Returns the latitude of the approximate center of the tile with a given index in the HEALPix NEST scheme.
    Note: the index parameter is 0-based, unlike the table row index special token $index (a.k.a. $0), which is 1-based. So if the HEALpix index is implicitly determined by the table row, the value $index-1 should be used.
    
    Parameters:
    
    k - HEALPix order (0..29)
    
    index - healpix index
    
    Returns:
    
    latitude in degrees
    
    See Also:
    
    HEALPix web site
  - healpixRingLon
```
public static double healpixRingLon(int k,
                                    long index)
```
    Returns the longitude of the approximate center of the tile with a given index in the HEALPix RING scheme.
    Note: the index parameter is 0-based, unlike the table row index special token $index (a.k.a. $0), which is 1-based. So if the HEALpix index is implicitly determined by the table row, the value $index-1 should be used.
    
    Parameters:
    
    k - HEALPix order (0..29)
    
    index - healpix index
    
    Returns:
    
    longitude in degrees
    
    See Also:
    
    HEALPix web site
  - healpixRingLat
```
public static double healpixRingLat(int k,
                                    long index)
```
    Returns the latitude of the approximate center of the tile with a given index in the HEALPix RING scheme.
    Note: the index parameter is 0-based, unlike the table row index special token $index (a.k.a. $0), which is 1-based. So if the HEALpix index is implicitly determined by the table row, the value $index-1 should be used.
    
    Parameters:
    
    k - HEALPix order (0..29)
    
    index - healpix index
    
    Returns:
    
    latitude in degrees
    
    See Also:
    
    HEALPix web site
  - healpixNestToRing
```
public static long healpixNestToRing(int k,
                                     long nestIndex)
```
    Converts a healpix tile index from the NEST to the RING scheme at a given order.
    Note: the nestIndex parameter is 0-based, unlike the table row index special token $index (a.k.a. $0), which is 1-based. So if the HEALpix index is implicitly determined by the table row, the value $index-1 should be used.
    
    Parameters:
    
    k - HEALPix order (0..29)
    
    nestIndex - pixel index in NEST scheme
    
    Returns:
    
    pixel index in RING scheme
    
    See Also:
    
    HEALPix web site
  - healpixRingToNest
```
public static long healpixRingToNest(int k,
                                     long ringIndex)
```
    Converts a healpix tile index from the RING to the NEST scheme at a given order.
    Note: the ringIndex parameter is 0-based, unlike the table row index special token $index (a.k.a. $0), which is 1-based. So if the HEALpix index is implicitly determined by the table row, the value $index-1 should be used.
    
    Parameters:
    
    k - HEALPix order (0..29)
    
    ringIndex - pixel index in RING scheme
    
    Returns:
    
    pixel index in NEST scheme
    
    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 (also variously known as order, level, depth) is the logarithm to base 2 of the Nside parameter.
    
    Parameters:
    
    pixelsize - pixel size in degrees
    
    Returns:
    
    HEALPix order 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 order (0..29)
    
    Returns:
    
    approximate angular resolution in degrees
  - healpixSteradians
```
public static double healpixSteradians(int k)
```
    Returns the solid angle in steradians of each HEALPix pixel at a given order.
    
    Parameters:
    
    k - HEALPix order (0..29)
    
    Returns:
    
    pixel size in steradians
  - healpixSqdeg
```
public static double healpixSqdeg(int k)
```
    Returns the solid angle in square degrees of each HEALPix pixel at a given order.
    
    Parameters:
    
    k - HEALPix order (0..29)
    
    Returns:
    
    pixel size in steradians
  - steradiansToSqdeg
```
public static double steradiansToSqdeg(double sr)
```
    Converts a solid angle from steradians to square degrees.
    The unit sphere is 4*PI steradians = 360*360/PI square degrees.
    
    Parameters:
    
    sr - quantity in steradians
    
    Returns:
    
    quantity in sqare degrees
  - sqdegToSteradians
```
public static double sqdegToSteradians(double sqdeg)
```
    Converts a solid angle from square degrees to steradians.
    The unit sphere is 4*PI steradians = 360*360/PI square degrees.
    
    Parameters:
    
    sqdeg - quantity in square degrees
    
    Returns:
    
    quantity in steradians
  - 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

Class Tilings

Field Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

SQDEG

Method Detail

htmIndex

healpixNestIndex

healpixRingIndex

healpixNestLon

healpixNestLat

healpixRingLon

healpixRingLat

healpixNestToRing

healpixRingToNest

healpixK

healpixResolution

healpixSteradians

healpixSqdeg

steradiansToSqdeg

sqdegToSteradians

htmLevel

htmResolution