Foreground: HI Column Density
The data made available through this page have been superseded by the Effelsberg-Bonn HI survey and the GASS HI survey.
The sky maps are generated using the HEALPix sky pixelization scheme. The first file listed for each map contains the data in its native HEALPix format. For the convenience of users who do not require the capabilities that HEALPix offers, we also provide the maps in two projected image formats: Mollweide and Zenith Equal Area (ZEA). These files contain the string "_mollweide" and "_zea" respectively, and may be displayed with standard astronomical display software such as DS9 and SAOImage. Note that the image pixels typically over-sample the HEALPix pixels, thus some amount of data replication will be present in the image data. As a result, care must be taken when using the image data in a regime where the noise properties are important since the statistical weight per pixel will also be replicated.
Recommended download procedure for '.fits' or '.tar.gz' files: