Mining The Sky 2000 Splitting the sky - HTM and HEALPix

Splitting the sky HTM and HEALPix. W. O’Mullane Astrophysics Division, Space Science Department of ESA, ESTEC, 2200 AG Noordwijk, The Netherlands. A. J. Banday MPI für Astrophysik, P.O. Box 1523, D-85740 Garching, Germany. K. Gorski European Southern Observatory (ESO), Karl Schwarzschild Strasse 2, 85748 Garching, Germany P. Kunszt, A. Szalay The Johns Hopkins University, 3701 San Martin Drive, Baltimore, MD 21218, USA. Abstract: Mission data sets are increasing in size and complexity. To enable efficient processing and storage of such data sets a tessellation scheme may be adopted. The Hierarchical Triangular Mesh (HTM) and the Hierarchical Equal Area isoLatitude Pixelisation (HEALPix) schemes are two popular schemes each with software tools available to exploit their particular properties. The initial drivers behind these two schemes are quite different but as their use continues the complimentary facilities of each package will become more relevant. Here we describe the motivation and facilities of HEALPix and HTM, we ask if it is possible to combine these schemes or make use of them in a combined manner and say why we may wish to do this.