The contribution of the Hipparcos mission and of the CCDM catalogue to the study of wide systems

Summary The general concept of theHipparcos astrometric mission is first recalled as well as the problems related to the observation technique of this satellite. TheInca Data Base and theHipparcos Input Catalogue are described and the place of the double and multiple stars in the mission and in theInput Catalogue is discussed. The need of a specific catalogue for these celestialobjects (CCDM) is shown and its format is given. The contribution of theHipparcos mission and of the CCDM to double star astronomy and more precisely to wide double and multiple systems is finally detailed.