  We present a catalogue of astrophysical data of 520 Galactic open clusters.
These are the clusters, for which at least three most probable members (18 on
average) could be identified in the ASCC-2.5, a catalogue of stars based on the
Tycho-2 observations from the Hipparcos mission. We applied homogeneous methods
and algorithms to determine angular sizes of cluster cores and coronae,
heliocentric distances, mean proper motions, mean radial velocities and ages.
For the first time we derive distances for 200 clusters, radial velocities for
94 clusters and determine ages of 196 clusters. This homogeneous new parameter
set is compared with earlier determinations. In particular, we find that the
angular sizes were systematically underestimated in the literature.
