Intermediate Data
The Hipparcos Intermediate Astrometric Data are described in Volume 1, Section 2.8 of the Hipparcos and Tycho Catalogues (ESA SP-1200, 1997).

The Hipparcos Catalogue contains the astrometric parameters derived for each of the stars observed in the Hipparcos programme. These are classified into (apparently) single systems, component solutions, orbital systems, systems with accelerating photocentres, etc. To preserve the elementary astrometric data from which these solutions have been derived, CD-ROM disk 5 of the Catalogue includes the so-called intermediate astrometric data (abscissae) and the associated reference-great-circle data. From these data, the individual observations can be inspected and their fit to the published astrometric solutions can be re-examined - for instance in the light of new data. The intermediate data also preserve access to the individual solutions provided by the two data analysis consortia (FAST and NDAC) before merging to form the final, published solution. The intermediate astrometric data can be retrieved (for individual Hipparcos stars) via the intermediate data tool.