Published online by Cambridge University Press: 04 August 2017
The raw data produced by the European Space Agency's astrometry satellite HIPPARCOS – mainly photon counts from the primary detector (IDT) and star mappers – will be analysed in full by two independent reduction consortia, FAST and NDAC. The aim is however to generate, by 1993, a single catalogue of positions, proper motions, and parallaxes for the 105 programme stars, with additional information on photometry, multiple stars, and minor planets. This review outlines some practical and theoretical features of the data reductions.