[fitsbits] HPX paper published

Greetings,

This is a straight cut-and-paste from my web page (without URLs):

------------------------------------------------------------------------

"Mapping on the HEALPix grid", Calabretta & Roukema, as submitted to
Monthly Notices of the Royal Astronomical Society (MNRAS) on
2007/06/26, introduces the HPX projection type. (PDF version)

The official refereed version of the paper, which will be published
as MNRAS 381 865, can be accessed from Blackwell Publishing now
(2007/10/01) via their online early system.

The paper mentions "a utility program that converts 1D HEALPix
pixelization data stored in a variety of forms in FITS, including ring
or nested organization in a binary table extension, into a 2D primary
image array with HPX coordinate representation".

This utility, HPXcvt, will be made available in WCSLIB 4.3. However,
as that has been delayed, the HPXcvt.c code is being released
separately, with an example of its application (13MiB bzip'd) to the
WMAP 3-year Internal Linear Combination map.

Compilation is straightforward, it does not depend on WCSLIB but does
need to be linked to CFITSIO. Use 'HPXcvt --help' for usage
instructions.

------------------------------------------------------------------------

Refer to http://www.atnf.csiro.au/people/mcalabre/WCS/index.html for the
links, which include a copy of the paper (as submitted), the HPXcvt C
code, and the WMAP ILC 3yr (v2) map. The salient point is that this
map is produced *without interpolation* of the pixelization data.

The final refereed version of the paper, available now from MNRAS online
early, contains a section comparing the six Goldberg-Gott distortion
indices of different members of the HEALPix class of projections. It
also mentions a new pole-centred layout, referred to as the Butterfly
projection (thanks to Stuart Lowe), which can be generated by HPXcvt.
Therefore I recommend getting the online early version if you are
subscribed.

Mark Calabretta
ATNF