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Pixel tiling functions for the celestial sphere.
-
htmIndex( level, ra, dec )
-
Gives the HTM (Hierachical Triangular Mesh) pixel index for a given
sky position.
-
level
(integer): HTM level
-
ra
(floating point): right ascension in degrees
-
dec
(floating point): declination in degrees
- return value (long integer): pixel index
-
healpixNestIndex( k, ra, dec )
-
Gives the pixel index for a given sky position in the HEALPix
NEST scheme.
-
k
(integer): resolution parameter - log to base 2 of nside
-
ra
(floating point): right ascension in degrees
-
dec
(floating point): declination in degrees
- return value (long integer): pixel index
-
healpixRingIndex( k, ra, dec )
-
Gives the pixel index for a given sky position in the HEALPix
RING scheme.
-
k
(integer): resolution parameter - log to base 2 of nside
-
ra
(floating point): right ascension in degrees
-
dec
(floating point): declination in degrees
- return value (long integer): pixel index
-
healpixK( 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.
-
pixelsize
(floating point): pixel size in degrees
- return value (integer): HEALPix resolution parameter
k
-
healpixResolution( 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.
-
k
(integer): HEALPix resolution parameter k
- return value (floating point): approximate angular resolution in degrees
-
healpixSteradians( k )
-
Returns the solid angle in steradians of each HEALPix pixel
at a given order.
-
k
(integer): HEALPix resolution parameter k
- return value (floating point): pixel size in steradians
-
healpixSqdeg( k )
-
Returns the solid angle in square degrees of each HEALPix pixel
at a given order.
-
k
(integer): HEALPix resolution parameter k
- return value (floating point): pixel size in steradians
-
steradiansToSqdeg( sr )
-
Converts a solid angle from steradians to square degrees.
The unit sphere is 4*PI steradians = 360*360/PI square degrees.
-
sr
(floating point): quantity in steradians
- return value (floating point): quantity in sqare degrees
-
sqdegToSteradians( sqdeg )
-
Converts a solid angle from square degrees to steradians.
The unit sphere is 4*PI steradians = 360*360/PI square degrees.
-
sqdeg
(floating point): quantity in square degrees
- return value (floating point): quantity in steradians
-
htmLevel( pixelsize )
-
Gives the HTM
level
parameter suitable for a given
pixel size.
-
pixelsize
(floating point): required resolution in degrees
- return value (integer): HTM level parameter
-
htmResolution( level )
-
Gives the approximate resolution in degrees for a given HTM depth level.
-
level
(integer): HTM depth
- return value (floating point): approximate angular resolution in degrees
-
SQDEG
-
Solid angle in steradians corresponding to 1 square degree.
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Next: Arithmetic
Up: Functions
Previous: Functions
STILTS - Starlink Tables Infrastructure Library Tool Set
Starlink User Note256
STILTS web page:
http://www.starlink.ac.uk/stilts/
Author email:
m.b.taylor@bristol.ac.uk
Mailing list:
topcat-user@bristol.ac.uk