Beschreibung:
<jats:title>Abstract</jats:title><jats:p>The Tycho Input Catalogue will be used as a finding list to identify the stellar data within the stream of raw data received from the Hipparcos star mappers. It is based on an a priori list of stars, namely the Guide Star Catalogue being created for the Hubble Space Telescope at the Space Telescope Science Institute. The Guide Star Catalogue will contain positions and magnitudes for objects in the sky complete to at least 14 mag, and will contain about 20 million stars. The data for the sky complete to approximately 12.5 mag, extracted from the Guide Star Catalogue, along with some additional data from the SIMBAD data base of about 500 000 stars at the Strasbourg Stellar Data Centre, will form the Tycho Input Catalogue of approximately 2 million objects. As of the 1985 IAU General Assembly nearly 50 per cent of the plates for the Guide Star Catalogue had been measured, and 10 per cent of them were completely processed and catalogued.</jats:p>