[fitsbits] HEALPIX fits files

[Andreas Wicenec]

Hi,

Mark: I just read your paper on HealPix and I think your extension is 
great indeed.
I have been working on a python port of the healpix software. That's 
not finished yet, but
part of it is already useable. If there is interest I am willing to 
work it through and
make it public.

Andreas

On 17.01.2005, at 05:31, Mark Calabretta wrote:

>
> On Thu 2005/01/13 13:47:05 CDT, Wayne Landsman wrote
> in a message to: fitsbits at donar.cv.nrao.edu
>
>> with a map projection, which will incorporated in V3.7  (not yet
>> released?) of WCSLIB.
>
> Should be released sometime soon.
>
>> I think this should eventually allow
>> astronomical display programs (DS9, AIPS) to convert Healpix maps to 
>> any
>> desired projection.
>
> HEALPix data is best displayed in the HEALPix projection itself because
> no regridding is required, you see the data directly without potential
> artifacts introduced by regridding.  All that is required is for a
> utility program to reorganize the 1-D vector (ring or nested) onto the
> 2-D grid.  The HPX projection type can then be used to add a graticule
> and this can be saved as a 2-D FITS image and viewed with any software
> that understands FITS WCS (with HPX).
>
> However, such an image is presented with an odd 45 deg rotation 
> (handled
> in the WCS via a PCi_j or CDi_j matrix).  The double-pixelisation
> eliminates this but is not as yet supported by any software.
>
> Mark Calabretta
> ATNF
>
>
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