HYPERLEDA. II. Homogenized HI data

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, log2V_M_^sini^, converted to the system of Mathewson et al. (1996ApJS..107...97M).

This quantity is given without correction for inclination; 2) the HI magnitude, m_21_, (area of the 21-cm line width expressed in magnitude) converted to the flux system of Theureau et al. (1998A&AS..130..333T); 3) the HI velocity, V_HI_, expressed with the optical definition (i.e., using wavelengths instead frequencies). The typical uncertainties are: 0.04 for log2V_M_^sini^, 0.25mag for m_21_ and 9km/s for V_HI_.