HYPERLEDA II. The homogenized HI data

After a compilation of HI data from 611 references and new observations made in Nançay, we produce a catalog of homogenized HI data for 16781 galaxies. The homogenization is made using the EPIDEMIC method from which all data are progressively converted into the adopted standard. The result is a catalog giving: 1) the logarithm of twice the maximum rotation velocity, …, converted to the system of Mathewson et al. (1996). This quantity is given without correction for inclination; 2) the HI magnitude, m21, (area of the 21-cm line width expressed in magnitude) converted to the flux system of Theureau et al. (1998); 3) the HI velocity, V HI, expressed with the optical definition (i.e., using wavelengths instead frequencies). The typical uncertainties are: 0.04 for  …., 0.25 mag for  m21 and 9 km s -1 for  V HI.