A reference tool for identication of astronomical sources

The Aladin interactive sky atlas, developed at CDS, is a service providing simultaneous access to dig- itized 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 cata- logues. The set of available sky images consists of the STScI Digitized Sky Surveys, completed with high resolution im- ages of crowded regions scanned at the MAMA facility in Paris.