I. Introduction

HEALPix is an acronym for Hierarchical Equal Area isoLatitude Pixelisation of the sphere. In the colour plot above you can see the green sphere partitioned by the low-resolution HEALPix grid of 768 pixels (~7.3 deg resolution), and two high-resolution examples of applications of HEALPix: the Earth topography map composed of 3,145,728 pixels (~7 arcmin resolution), and a model of the Cosmic Microwave Background (CMB) radiation temperature anisotropy composed of 12,582,912 pixels (~3.4 arcmin resolution).

HEALPix was originally devised in early 1997 by Krzysztof M. Górski at the Theoretical Astrophysics Center (TAC) in Copenhagen (now at JPL/Caltech in Pasadena). Early development of the HEALPix concept and initial implementation was made in the spring of 1997 in collaborative work of K.M. Górski with Eric F. Hivon, currently at Caltech. Benjamin D. Wandelt, then at the TAC (now at the University of Illinois at Urbana-Champaign), has contributed critically to the further development of HEALPix and related mathematical methods. Frode K. Hansen, then at the TAC (now at Universita Roma II), Anthony J. Banday, and Matthias Bartelman (both at the Max Planck Institut für Astrophysik in Garching) provided invaluable input required to make possible the first large release of the HEALPix software Version 1.10.

The present release of the HEALPix software Version 1.20 benefited from both the continuing dedicated effort of Eric Hivon, Martin Reinecke (MPA), and Anthony J. Banday, and numerous contributions made by HEALpix users (see the Acknowledgements ).

The active support of HEALPix currently involves the following people:
K.M. Górski (JPL/CalTech), E. Hivon (CalTech), M. Reinecke (MPA-Garching), and A.J. Banday (MPA-Garching).
This effort is not supported by any dedicated funds, and depends entirely on the voluntary collaboration of the mentioned individuals.