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The HEALPix Software Package

We have developed a package of HEALPix based mathematical software, consisting of Fortran90 and IDL source codes as well as documentation and examples. Successful installation produces a set of facilities using standardised FITS I/O interfaces ( as well as two Fortran90 libraries which users can link to their own applications. Among the tasks performed by the components of the HEALPix package are the following:

* Simulation of the full sky CMB temperature and polarisation maps as realisations of random Gaussian fields, with an option to constrain the realisation by prior information.
* Analysis of the full sky CMB temperature and polarisation maps resulting in power spectra and/or spherical harmonic coefficients. Relevant conventions are given in Appendix A. Note that the convention used for polarization has been changed !.
* Global smoothing of whole sky maps with a Gaussian kernel.
* Degradation and upgrade of the resolution of discrete maps.
* Global searches on the maps for nearest-neighbours and the maxima/minima of the discretised functions.
* Algebraic conversion of the maps between the RING and NESTED numbering schemes, and mapping back and forth between positions on the sphere and discrete pixel index space.
* Pixel queries for various geometrical shapes (discs, triangles, polygons ...)
* Visualisation of the HEALPix formatted sky maps in the Mollweide, orthographic, cartesian cylindrical and gnomonic projections of the whole sky or small areas of it.

The package includes documents which describe the installation process, the Fortran 90 facilities, the IDL facilities and a large number of subroutines contained in the library. It is available to the scientific community at

HEALPix is the format chosen by the WMAP collaboration to be used for the production of sky maps (see from the mission data.

HEALPix software is widely used for simulation work within both the LFI and HFI consortia of the Planck collaboration (see

It is also being used to analyse the data provided by the balloon CMB missions Boomerang (see or and Archeops (

Eric Hivon 2010-06-18
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