The Hipparcos and Tycho Catalogues This is one of the six CD-ROM sets containing the Hipparcos and Tycho Catalogues: astrometric and photometric star catalogues derived from the ESA Hipparcos Space astrometry mission. Contents of the Catalogues: Each of the catalogues includes a large quantity of very high quality astrometric and photometric data, as well as annexes featuring variability and double/multiple star data. In the case of the Hipparcos Catalogue, the principal parts are provided in both printed and machine-readable form. In the case of the Tycho Catalogue, results are provided in machine-readable form only. Although in general only the final reduced and calibrated astrometric and photometric data are provided, some auxiliary files containing results from intermediate stages of the data processing, of relevance for the more-specialised user, have also been retained for publication. The contents of the Hipparcos and Tycho Catalogues, and their associated annexes, have been distributed across the CD-ROM set. Each CD-ROM contains a complete catalogue or annex along with associated index files. Disc 1 also contains figures (lightcurves), tables, notes and references which are related primarily to the catalogues contained on that disc. Identification charts are found on disc 2, in addition to data files. The directory structure and contents, and data formats, are described in the printed documentation (Section 2.11 of Volume 1 "Introduction and Guide to the Data"), and in the corresponding files of that documentation in the directory `docs' (on disk 1). Data Format: The data in each catalogue file is stored in ASCII. The conventions adopted for writing these ASCII files are described in Section 2.11 of Volume 1. The Fortran format for each machine-readable catalogue or annex is given in the appropriate section of Volume 1. Users should note that the main data and index files are written with PC end-of-line characters (`carriage return' plus `line feed'). All other files, with the exception of readme.dos and readme.mac, are written with UNIX end-of-line characters. Software and Related Utilities: For each data file and index file a C (.c) and header (.h) file is provided, along with some auxiliary C and header files, to facilitate access to the data files. In addition, for each data file which has an associated index file, a search routine is supplied. These files are all located in the `src' directory on disc 1. Documentation (readme.doc, readme.pdf) providing more detailed information about the C and header files and their use is also found in `src'. C and Fortran 77 subroutines are provided for epoch transformation of the astrometric parameters and their covariances. These files (pos_prop.f, pos_prop.c, pos_prop.h) are located in `src'. A description of the code is embedded at the start of each file. Further information is available in Section 2.11 of Volume 1. Some users may prefer to convert the catalogues and/or annexes into FITS format. The Centre de Donnees astronomiques de Strasbourg (CDS), provides publicly available software which will convert ASCII data files to FITS format. The software (ana.tar.gz) is available from the anonymous ftp account on cdsarc.u-strasbg.fr (in directory /pub/sw). In addition to the ASCII datafile, the program `tofits' requires a catalogue description file. This file (tofits.dat) is included on disc 1 in directory `fits'. The file tofits.doc gives details on how to obtain the software and on the contents of the tofits.dat file. CD-ROM Format: This CD-ROM set is formatted for the ISO 9660 Standard, Data Interchange Level 1. File names at this interchange level are restricted to at most 8 characters, followed by a full-stop, ".", followed by at most a three-character extension, followed by a version number suffix, which is ";1" in every case. The appearance of the file names (uppercase or lowercase, with or without version numbers) depends on the computing platform, operating system, and device-driver software used to access the CD-ROM. Other Hipparcos Products: The Hipparcos and Tycho Catalogues are also available in printed form, as ESA SP-1200. The printed volumes include a description of the Hipparcos and Tycho Catalogues and associated annexes, a description of the satellite operational phase, a description of the corresponding data analysis tasks, and the appropriate subsets of the final data. A single CD-ROM product, Celestia 2000, contains the principal astrometric and photometric data in compressed form, along with specific interrogation software. Background Information: The Hipparcos astrometry mission was accepted within the European Space Agency's scientific programme in 1980. The Hipparcos satellite was designed and constructed under ESA responsibility by a European industrial consortium led by Matra Marconi Space (France) and Alenia Spazio (Italy), and launched on Ariane 4 on 8 August 1989. High-quality scientific data were acquired between November 1989 and March 1993, and communications with the satellite were terminated on 15 August 1993. All of the scientific goals motivating the mission's adoption in 1980 were surpassed. The products of the Hipparcos mission are two major astrometric catalogues, the Hipparcos Catalogue (of 118218 stars) and the Tycho Catalogue (of more than one million stars), both derived from instruments on board the Hipparcos satellite. The global data analysis tasks, proceeding from nearly 1000 Gbit of raw satellite data to the final catalogues, was a lengthy and complex process, and was undertaken by the NDAC and FAST Consortia, together responsible for the production of the Hipparcos Catalogue, and the Tycho Consortium, responsible for the production of the Tycho Catalogue. A fourth scientific consortium, the INCA Consortium, was responsible for the construction of the Hipparcos observing programme, compiling the best-available data for the selected stars before launch into the Hipparcos Input Catalogue. The production of the Hipparcos and Tycho Catalogues marks the formal end of the involvement in the mission by the European Space Agency and the four scientific consortia. Contact addresses: For Hipparcos mission related aspects: M.A.C. Perryman Astrophysics Division, ESTEC Noordwijk 2200AG, The Netherlands For aspects related to the Hipparcos Catalogue: L. Lindegren Lund Observatory, Box 43 22100 Lund, Sweden J. Kovalevsky Observatoire de la Cote d'Azur CERGA, Avenue Copernic 06130 Grasse, France For aspects related to the Tycho Catalogue: E. Hoeg Copenhagen University Observatory Juliane Maries Vej 30 2100 Copenhagen OE, Denmark For aspects related to the Hipparcos Input Catalogue: C. Turon Section d'Astrophysique Observatoire de Paris 92195 Meudon Cedex, France Other members of the ESA Hipparcos Science Team: U. Bastian Astronomisches Rechen-Institut Moenchhofstrasse 12-14 69120 Heidelberg, Germany P.L. Bernacca Astrophysical Observatory Via dell'Osservatorio 36102 ASIAGO (Vicenza), Italy M. Creze 18 rue Nicolazic 56400 Sainte Anne d'Auray, France F. Donati Centro di Studi Sui Sistemi Via Vincenzo Vela 27 10128 Torino, Italy M. Grenon Observatoire de Geneve 1290 Sauverny, Switzerland M. Grewing IRAM, 30 rue de la Piscine Domaine Universitaire, St Martin d'Heres 38406 France F. van Leeuwen Royal Greenwich Observatory Madingley Road Cambridge CB3 0EZ, United Kingdom H. van der Marel Department of Geodesy Delft University of Technology, Thijsseweg 11 2629 JA Delft, The Netherlands F. Mignard Observatoire de la Cote d'Azur CERGA, Avenue Copernic 06130 Grasse, France C.A. Murray Derwent Cottage, 12 Derwent Road Eastbourne Sussex BN20 7PH, United Kingdom R.S. Le Poole Sterrewacht Leiden, Postbus 9513 2300 RA Leiden, The Netherlands J.H. Schrijver SRON Space Research Utrecht Sorbonnelaan 2 3584 CA Utrecht, The Netherlands