Abstract.Simbad is the reference database for identification and bibliography of astronomical objects. It contains identifications, "basic data", bibliography, and selected observational measurements for several million astronomical objects.Simbad is developed and maintained by CDS, Strasbourg. Building the database contents is achieved with the help of several contributing institutes. Scanning the bibliography is the result of the collaboration of CDS with bibliographers in Observatoire de Paris (DASGAL), Institut d'Astrophysique de Paris, and Observatoire de Bordeaux.When selecting catalogues and tables for inclusion, priority is given to optimal multi-wavelength coverage of the database, and to support of research developments linked to large projects. In parallel, the systematic scanning of the bibliography reflects the diversity and general trends of astronomical research.A WWW interface to Simbad is available at: http://simbad.u-strasbg.fr/Simbad.

Abstract. The Aladin interactive sky atlas, developed at CDS, is a service providing simultaneous access to digitized images of the sky, astronomical catalogues, and databases. The driving motivation is to facilitate direct, visual comparison of observational data at any wavelength with images of the optical sky, and with reference catalogues.The set of available sky images consists of the STScI Digitized Sky Surveys, completed with high resolution images of crowded regions scanned at the MAMA facility in Paris.A Java WWW interface to the system is available at: http://aladin.u-strasbg.fr/.

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Abstract. The Centre de données astronomiques de Strasbourg (CDS) provides homogeneous access to heterogeneous information of various origins: information about astronomical objects in Simbad; catalogs and observation logs in VizieR and in the catalogue service; reference images and overlays in Aladin; nomenclature in the Dictionary of Nomenclature; Yellow Page services; the AstroGLU resource discovery tool; mirror copies of other reference services; and documentation. With the implementation of links between the CDS services, and with other on-line reference information, CDS has become a major hub in the rapidly evolving world of information retrieval in astronomy, developing efficient tools to help astronomers to navigate in the world-wide "Virtual Observatory" under construction, from data in the observatory archives to results published in journals.The WWW interface to the CDS services is available at: http://cdsweb.u-strasbg.fr/

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