The development of software and hardware technology now allows to develop new kinds of interactive access to all sort of astronomical data. In the same time, astronomers of 1993 looking for optical counterparts of gamma-ray to radio sources, need to go beyond already existing catalogs or databases. From these two main considerations came the idea to propose a complete ``on-line'' digitized sky atlas.
This atlas should be a public interactive tool, available for all laboratories through networks. It should allow any astronomer to point a region of the sky, to display the corresponding digitized image (with accurate positions and fluxes), and to overlay cataloged data from the SIMBAD data base (Egret et al. 1991) and CDS catalogs.
More details about this project initiated by the CDS in 1992 can be found in Paillou et al. (1993, 1994). We will focus here on the most recent developments on the project, and on the use of the client/server approach in the overall architecture of the system.