Paris
Observatory (Observatoire de Paris) is the oldest
astronomical observatory still in use. It was built (1667-72) in
Paris under Louis XIV by the architect Claude Perrault at the instigation of Jean Picard and J. B. Colbert. The
observatory's first director was Giovanni Domenico Cassini. In 1887 a congress at Paris agreed to create the Carte du Ciel (Map of the Heavens; see
astronomical catalogs and atlases) Work began at the Paris Observatory in 1890, and eventually the Carte included data on over 2 1/2 million stars. Today the Paris Observatory has observational sites outside Paris. One is the Meudon Observatory founded by Jules Janssen in 1876. Instruments at Meudon include a 3.3-ft (1-m) reflector and a 16-in (40-cm) wide-angle Schmidt camera telescope. A radio astronomy observatory called Station Radioastronomique de Nancay, in the Sologne district, is also attached to the Paris Observatory, as well as a site on the plateau of Calern, Centre d'Etudes et de Recherches GŽodynamiques et Astronomiques (CERGA). The observatory is also the headquarters of the International Time Bureau.