Zeroth and second moment maps toward M 31. Top: the zeroth moment (left) and the second moment map (right) calculated for the radial velocity range −588 ≤ v_LSR [ km s^-1 ] ≤ −25 are presented. The disk of M 31 is easy to identified in both maps. Prominent in the second moment map are also the lopsided HI structures displayed in Fig. 1. In addition, HI clouds along the bridge toward M 33 and isolated HI features like Davies cloud (Davies 1975) show by their color coding their deviation from the Milky Way Galaxy HI emission. Bottom: zeroth moment (left) and the second moment map (right) calculated for the radial velocity range −75 ≤ v_LSR [ km s^-1 ] ≤ −25. About 99% of all HI in the area of interest are comprised in these maps. While the top and bottom zeroth moment maps displayed appear to differ only in the extent of M 31 HI disk, the second moment maps display totally different structures. We note the very different velocity ranges of both second moment maps and the equal column density range of the zeroth moment maps.