The HI4PI survey is an all-sky HI survey, based on data from the Effelsberg-Bonn HI survey (EHBIS) and from the third revision of the Parkes Galactic All-Sky Survey (GASS). The EHBIS map (10.8') has been smoothed to match the angular resolution of the GASS map (16.2'). The resulting Healpix map has an angular resolution of 16.2'. Units are cm-2.

A full description of the HI4PI survey can be found here: http://adsabs.harvard.edu/abs/2016A%26A...594A.116H

The WCS data files can be downloaded here: https://www.astro.uni-bonn.de/hisurvey/AllSky_profiles/index.php