Any astronomer, whether preparing observation runs or reducing data, requires access to information concerning the objects under investigation. Ideally the data should be from several wavelengths and should be as quantitative as possible. This leads to the concept of developing simultaneous interactive access to sky surveys, initially at optical wavelengths, and with state-of-the-art information systems for all field objects.

In order to satisfy this requirement, the CDS (Centre de Données astronomiques de Strasbourg) is developing a ‘Deep Sky Mapping Facility’ project, Aladin, which aims to connect the data stored at CDS (astronomical catalogues and Simbad), to pixel data from continuously updated deep optical sky surveys.