DISTRIBUTION AND ORIGIN OF HIGH-VELOCITY CLOUDS .3. CLOUDS, COMPLEXES AND POPULATIONS

We present the first complete catalogue of high-velocity clouds (HVCs), followed by a classification of these clouds into complexes and populations. The catalogue will form the basis for comparisons with theoretical models. The study described here yields the following conclusions: (1) Differential galactic rotation makes a large contribution to observed radial velocities, so that clouds with negative velocity occur mainly in the first and second longitude quadrants and those with positive velocity in the third and fourth quadrants, except within 45-degrees of the galactic center.(2) The present, more complete data still show the separation between very-high-velocity clouds (VHVCs, upsilon-1sr <-200 km s-1) and HVCs (upsilon-1sr > -200 km s-1) noted by Hulsbosch (1978a) and Giovanelli (1980).(3) Based on the distributions in longitude, latitude and velocity of the catalogued clouds, ten different populations and seventeen HVC complexes have been identified. For most of the complexes maps are presented (Fig. 1).(4) From the catalogue the flux and area distributions of clouds [log N (> S) and log N (> OMEGA)] have been be produced. These contain information on the space density and mass function of HVCs. It is shown that the differential mass spectrum has a slope of approximately -3/2.