PROPERTIES OF THE HIPPARCOS-INPUT-CATALOG

The positions, proper motions, magnitudes and colour indices contained in the Hipparcos Input Catalogue are compared with preliminary Hippar cos mission results. The Hipparcos data considered, the 'combined 30-m onth solution', or H30, is a preliminary catalogue derived from the an alysis of the first 30 months of data (out of a total of 37 months), a nd represent the union of the latest intermediate FAST and NDAC Consor tia's sphere solutions. The preliminary catalogue H30 is of unpreceden t accuracy, and allows the accuracies claimed by the various sources o f ground-based data included in the Hipparcos Input Catalogue, both as trometric and photometric, to be verified.