Carte du Ciel

An ambitious project, started in 1887, intended to produce photographic charts of the entire sky, together with an associated star catalogue. The charts were never completed, the standard methods ultimately being overtaken by technical advances in astrophotography. During the 1880s, the growing importance of photography in astronomy became apparent. In 1885, a 34-cm (13.5-inch) photographic refractor was constructed at the Paris Observatory by Paul and Prosper Henry. Impressed by their achievements, the Director, E. B. Mouchez, with encouragement from Sir David Gill and Otto Struve, organized the Astrographic Congress of April 1887. The permanent committee met five times before it was transferred to the auspices of the International Astronomical Union in 1919. The work was initially divided among eighteen observatories, though notably none in the USA. The Paris instrument was adopted as the standard prototype. Each plate was to be two degrees square with a superimposed grid of fine lines at 5-mm (0.2-inch) intervals. A total of about 22,000 plates was taken, only a quarter of the number originally projected. However, the publication of the associated Astrographic Catalogue was finally completed in 1964.