Heliograph4 inch (10 cm) |
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Index:
Summary; History; Current; Technical; Sources; Links; Gallery:
In brief
Important Contributions:
Description:
Used since 1910 to take two photographs of the sun per day (weather permitting). The photos were sent to Royal Greenwich Observatory.
Historical Background
Owner:
Cape Observatory
Where Located:
Cape Observatory
Current Information
Present Location:
SAAO
Owner:
SAAO
Status:
Used occasionally for public viewing.
Condition:
Operational
Technical Details
Type: Reflector / Refractor
Aperture: 4 inch (10.16 cm) giving an 8-inch (20.32-cm) picture
Focal Length:
Mirror / Lens:
Mounting: Troughton and Simms
Attachments:
Manufacturer: Dallmeyer of London
Operational History: The Photoheliograph was first installed in 1875-6 in a wooden hexagonal hut near the present day Astrographic Telescope. In 1911 the telescope was attached to the Astrographic Telescope until 1929 when the Photogeliograph was moved to it’s own building – the oldest dome at the Observatory terrain where the 7′ Mertz was originally housed [Glass]
Building: The heliometer stood in the dome which first housed the 7-inch Mertz telescope (18-inch dome). A unique feature of the dome is that it revolves on six cannon balls. [Koorts p. 52]
Sources
Link to the Main Bibliography Section and more information about Sources.
Documentation:
Pictorial Sources:
Bibliography:
- Koorts, W.: The 1882 transit of Venus: The British expeditions to South Africa; MNASSA April 2004, Vol. 63 nos. 3 & 4, pp. 34 – 57.
- Laing, J.D. (ed.), The Royal Observatory at the Cape of Good Hope 1820 – 1970 Sesquicentennial Offerings, p.32.
Links
Gallery
Reginald de Kock at the eyepiece of the Heliometer.
Source: A.S.S.A. Archives: Peter Smits Collection
View of the telescope on the Troughton and Simms Mounting.
View of the screen of the telescope assembly where the image of the sun is projected.
The Photoheliograph dome is the oldest dome at the Observatory grounds. It was erected in 1849 to house the 7′ Mertz Telescope. The Photoheliograph was installed in 1929 in this dome.
Circa 1962. (Photo Credit: Greg Roberts)