The Carte du Ciel enterprise

A brief historical account


Following the promising results deriving from the use of photography in astronomy, in 1887 Ernest Mouchez (1821-1892), Director of the Paris Observatory, launched the Carte du Ciel enterprise, an international project aimed at realizing a photographic chart of the entire celestial vault through the collaboration of eighteen observatories.

After four years of studies and trials, the Committee in charge of the work decided that each institution should make a double series of plates for the sky zone assigned, in order to realize a photographic chart with stars up to the 14th magnitude, and an Astrographic Catalogue including stars up to the 11th magnitude. Each observatory, on average, would have to take over two thousand photographs for both projects, in order to cover the entire celestial vault. By allowing not more than one hundred nights per year, the whole photographic work would take about six years.

However, the enterprise on the whole took much, much longer than expected. First, because the amount of work and personnel required to carry out the project was enormous, since each Catalogue plate had to be measured and the deduced right ascensions and declinations published after reduction to a common equinox. Secondly, the shortage of personnel and/or funds, plus the outburst of two world conflicts delayed the project even further.

In 1964, the International Astronomical Union announced the accomplishment of the Catalogue. By then, the technological development and the new perspectives of astronomy had rendered obsolete the continuation of the star charting work. In 1970 at the IAU 14th General Assembly held in Brigton, UK, it was acknowledged that the Carte du Ciel enterprise remained unachieved.


Donatella Randazzo, 6 November 2012