Structure and kinematics of large spiral galaxies

We parametrise the structure and kinematics of four large and massive spiral galaxies in terms of a tilted-ring model of the Hi disk. Only one of the examined galaxies shows a typical warp structure, suggesting that warps are rarer towards larger masses of spiral galaxies. The galaxies show a sharp drop in the Hi surface density profile at a large radius, which determines the edge of the Hi disk. Beyond this edge we do not detect any neutral gas. Including the results of earlier, similar studies, we find a possible anti-correlation of the size of Hi disks of spiral galaxies (in terms of optical radii) with the optical radius of a galaxy. An extremely massive Hi cloud without any stellar counterpart in the DSS2 is found to interact with UGC 2153.