1997A&AS..123...43S

We present high resolution images of the entire galactic HI spectrum of Cas A and display the whole data cube in various ways; the spatial resolution is 30 arcsec and the velocity resolution is 0.62km/s. In previous studies, observations are described either with lower velocity resolution or with a limited velocity range (below -30km/s), (Bieging et al. 1991ApJS...75..999B; Reynoso et al. 1997A&A...317..203R). Here we concentrate the discussion on the local HI gas, with velocities between -10 and +10km/s. At a velocity of -1.5km/s we find a cold HI feature with a kinetic temperature of typically 25K, with a small region of 1 by 2arcmin with a kinetic temperature below 10K. This feature can be associated with a ¹³CO feature observed by Wilson et al. (1993A&A...280..221W). Based on the new HI absorption results we derive the ratio N_HI/N(H₂)≃0.05 .