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Cape Photographic Durchmustering (CPD)

In Brief:

Observatories involved: Royal Observatory, Cape of Good Hope

Instruments used:




Description: -It was the first major astronomical work to be carried out photographically.
-This Catalogue gives the approximate positions and magnitudes of nearly half a million Southern Hemisphere stars. (454 875 stars south of -19degrees)


History: Sir David Gill took a photograph of a comet and as he studied the photograph, he realised the possibility of photography for making star-maps down to very faint magnitudes. Gill ordered a lens from Dallmeyer, the famous optical worker, ordering a lens. “The outcome was the famous CPD or Cape Photographic Durchmusterung, which extended the Bonn Durchmusterung down to the South Pole of the sky. Funds for the work were sought from the Royal Greenwich Observatory, but were refused, mainly because of a misunderstanding. Fortunately, the Royal Society gave him a grant, which covered the expenses of bringing a specialist photographer out from England, and a generous friend donated a further sum. There was still a shortfall, however, so Gill made it up out of his own pocket the not-inconsiderable amount of £350 per year (worth many times as much today), during all the years that work on the Durchmusterung was in progress. The finished catalogue gives the brightness and approximate positions of nearly half a million southern stars.” [Copied from Moore, p. 76.]
The plates were measured and reduced by Prof. Kapteyn of Groningen.
This project laid the foundation of Dutch – South African collaboration in Astronomy.



-Laing, J.D. (ed.), The Royal Observatory at the Cape of Good Hope 1820 – 1970 Sesquicentennial Offerings, p. 13.
-Moore, P. & Collins, P., Astronomy in Southern Africa, p. 76. (General Source)