Carte du Ciel

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Carte Du Ciel (CdC)

In Brief:

Observatories involved: Royal Observatory, Cape of Good Hope
Instruments: Astrographic TelescopeDuration: 1892 to 1936.



Description: This was one of the first attempts to make a photographic catalogue of the sky. The Paris Observatory initiated the project and a few Observatories around the world participated. A zone was assigned to the Royal Observatory, Cape of Good Hope, -40 to -52 degrees. This area became one of the best observed in the sky. The material formed one of the most important sources for its time for studies of stellar motions. The project was over ambitious and it took many years to complete.


CdC was an international collaboration project headed by the Paris Observatory.
Sir David Gill, director of the Royal Observatory, Cape of Good Hope, and father of Astrophotography was one of the leaders of the project.
The Royal Observatory, Cape of Good Hope was busy with the first attempt to make a photographic map of the sky, called the
Cape Photographic Durchmustering (CPD). Even while work on the CPD was going on, the Paris Observatory, which became known as Carte Du Ciel (CdC), put a larger and even more ambitious project in hand.
This was nothing less than a photographic chart of the whole sky. The aim was to prepare a photographic chart of the heavens showing stars down to the fourteenth magnitude, together with a catalogue giving the precise positions of stars down to the eleventh magnitude.
“A scheme of this kind could be carried through only with the co-operation of many astronomers and many observatories. As the acknowledged “father of astrography”, Gill was prominent both in the organising and the carrying-out of this great work. … A major portion of the work was carried out at the Cape Observatory and a fine new telescope, the astrographic refractor, was acquired. Yet in spite of the devotion of Gill and his colleagues, work on the Carte du Ciel was not completed until a few years ago (date). The whole concept was simply too big for late-19th century facilities.” [Copied from Moore, p. 79.]
“The zone assigned to the Cape, from -40 degrees to – 52 degrees, has become one of the best observed parts of the sky. In it the positions of nearly half a million stars were carefully measured for an epoch of approximately 1900. The zone was re-photographed some twenty-five years later and proper motions were derived for the 40 000 brightest stars and for those fainter stars having large proper motions. This material forms one of the most important sources yet available for studies of stellar motions.” [Copied from Laing, p.30.]
Five of the twelve volumes giving the results of the measures for the Cape Zone of the Astrographic Catalogue were published during Hough’s (1907 – 1923) term of office. [Moore, p. 79]
-1892: The Royal Observatory, Cape of Good Hope acquired the Astrographic refractor for this project.
-1896: The Cape Zone set of photographs completed.
-1926: All plates measured and the 12-volume catalogue published.
Project completed. The project was too ambitious for the technology of the time and took very long to complete.


Bibliography: -Laing, J.D. (ed.), The Royal Observatory at the Cape of Good Hope 1820 – 1970 Sesquicentennial Offerings, p. 13; p.30
-Moore, P. & Collins, P., Astronomy in Southern Africa, p.79. (General Source)