Another Way to Explore the Sky: HEALPix Usage in Aladin Full Sky Mode

摘要

The last few years have seen the emergence of new visualization tools such as Google Sky and Microsoft World Wide Telescope supporting im-mediate full sky panning and zooming. All these tools have in common a view of the sky based on a hierarchical multi-resolution sky tessellation. The aim is to load and draw the good pieces of the sky at the good resolution as fast as possible, according to the current user sky view. The goal is the same but sky indexing solutions differ significantly and do not offer the same capabilities in term of performances, underlying data base complexity, available projections, projection distortion, pixel value access, graphical overlays, etc. Actually, most of the tools offer false-colour skies with a unique simple projection. But this new feature can be used not only for providing a sky background, but also for accessing and analyzing pixel data in the same way that astronomers commonly use FITS images for doing science. We will present how Aladin is using an HEALPix sky tessellation for building a powerful sky data base.