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.
healpixNestIndex( k, lon, lat )
k
(integer): HEALPix order (0..29)
lon
(floating point): longitude in degrees
lat
(floating point): latitude in degrees
healpixRingIndex( k, lon, lat )
k
(integer): HEALPix order (0..29)
lon
(floating point): longitude in degrees
lat
(floating point): latitude in degrees
healpixNestLon( k, index )
k
(integer): HEALPix order (0..29)
index
(long integer): healpix index
healpixNestLat( k, index )
k
(integer): HEALPix order (0..29)
index
(long integer): healpix index
healpixRingLon( k, index )
k
(integer): HEALPix order (0..29)
index
(long integer): healpix index
healpixRingLat( k, index )
k
(integer): HEALPix order (0..29)
index
(long integer): healpix index
healpixNestToRing( k, nestIndex )
k
(integer): HEALPix order (0..29)
nestIndex
(long integer): pixel index in NEST scheme
healpixRingToNest( k, ringIndex )
k
(integer): HEALPix order (0..29)
ringIndex
(long integer): pixel index in RING scheme
healpixK( pixelsize )
k
value is the logarithm to base 2 of the
Nside parameter.
pixelsize
(floating point): pixel size in degrees
k
healpixResolution( k )
k
This k
value is the logarithm to base 2 of the
Nside parameter.
k
(integer): HEALPix order (0..29)
healpixSteradians( k )
k
(integer): HEALPix order (0..29)
healpixSteradians(5) = 0.0010226538585904274
4*PI/healpixSteradians(0) = 12.0
healpixSqdeg( k )
k
(integer): HEALPix order (0..29)
healpixSqdeg(5) = 3.357174580844667
round(12 * healpixSqdeg(0)) = 41253
steradiansToSqdeg( sr )
The unit sphere is 4*PI steradians = 360*360/PI square degrees.
sr
(floating point): quantity in steradians
round(steradiansToSqdeg(4*PI)) = 41253
sqdegToSteradians( sqdeg )
The unit sphere is 4*PI steradians = 360*360/PI square degrees.
sqdeg
(floating point): quantity in square degrees
round(sqdegToSteradians(41253)/PI) = 4
htmLevel( pixelsize )
level
parameter suitable for a given
pixel size.
pixelsize
(floating point): required resolution in degrees
htmResolution( level )
level
(integer): HTM depth
SQDEG