An extragalactic data base II. The HI data.

A compilation of raw H I data has been made as a part of a big project of collecting astrophysical parameters for more than 70000 galaxies. This information is managed with a specialized Extragalactic Data Base system. Corrections to produce homogenized H I-parameters are deduced from the compilation made for the Extragalactic Data Base. All raw 21 cm line widths are reduced to a common system of widths at 20% and 50% of the peak. They are corrected for velocity resolution effect and tested for homogeneity reference by reference. The H I fluxes converted to uniform units system (log of 10^-24^W m^-2^) are corrected. when necessary, for beam-filling effect. The homogenized mean fluxes are tested for scale and zero-point errors and also for a reference effect. Heliocentric H I-velocities are reduced in the same way. These results have been used to produce a catalogue of weighted mean H I-parameters for 6439 galaxies.