DOUBLE STAR DATA IN THE HIPPARCOS CATALOG

The Hipparcos Catalogue contains astrometric results for 117 955 catal ogue entries, many of which are in reality double or multiple stars. F or 17 917 entries special solutions were made in order to cope with th e various manifestations of multiplicity, and 6763 other entries were flagged as suspected binaries but solved as single stars. Details of t he special solutions are contained in the Hipparcos Catalogue Double a nd Multiple Systems Annex, divided in five parts according to the type of solution: resolved systems (13 211 entries with a total of 24 588 components), astrometric binaries with curved proper motion (2622 entr ies) or orbital solutions (235 entries), 'variability-induced movers' (288 entries) and 'stochastic' solutions (1561 entries). Trigonometric parallaxes and the positions and proper motions in the extragalactic reference system ICRS are provided for all entries.