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Astron. Astrophys. 363, 991-994 (2000)

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1. Introduction

In 1980 the Hipparcos project was endorsed by the European Space Agency. It was already known that the mission would need the establishment of an Input Catalogue of all the objects to be observed. This catalogue of more than 100000 stars should report their positions with an accuracy of [FORMULA] and their magnitudes with an accuracy of [FORMULA]m.

Whereas many catalogues exist to help define these parameters for the single stars, no such references exist for double and multiple systems; the best available general catalogue of all known such objects is the Index Catalogue (Jeffers & van den Bos 1963) regularly updated since 1964 by Worley at the US Naval Observatory. This catalogue gives the positions of the systems to a numerical accuracy of only [FORMULA] and shows, in many cases, an effective error of 2 to 3´, due to the techniques used and to the fact that some systems have angular dimensions larger than one arc minute. This imprecision was acceptable for works pursued by the double star specialists but unfortunately not for the space mission.

As coordinator of the Double Star Working Group inside the Input Catalogue Consortium (INCA), we began the creation of a specific double star catalogue based on the Index (updated to July 1976) but providing accurate positions to [FORMULA] or better for at least one component per system. To achieve this, each record was limited to one component only. After more than ten years of work, consisting of catalogue cross-identifications, bibliographic researches, organisation of observation campaigns by devoted members of a Double Star Working Group, and making partial use of the most recent edition of the Index (the WDS catalogue, Worley & al. 1984), this catalogue, called Catalogue of the Components of Double and Multiple stars (CCDM), contained 34031 systems, of which at least one component was located with an accuracy of 1 arcsecond. The CCDM served as the basic data file to establish Annexe 1 (vol. 6) of the Hipparcos Input Catalogue (Turon et al. 1992) containing 14167 accurately identified double and multiple systems. The historical sketch of the CCDM has been given elsewhere (Dommanget & Nys 2000).

However, during the operational period of the mission and since the publication of the first version of the CCDM (Dommanget & Nys 1994a,b), the identification process continued. Based on a copy of the WDS Catalogue - heir of the Index - updated to January 1, 1994 and kindly put at the disposal of the Double Star Working Group of the Hipparcos Science Team by Worley (1994), two more lists of identifications were published (Dommanget & Nys 1995, 1996). Unfortunately these were not fully taken into account when the final Hipparcos Catalogue and Celestia 2000 (ESA 1997) were realized (Dommanget 2000).

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© European Southern Observatory (ESO) 2000

Online publication: December 5, 2000