Heliograph 4  inch (10 cm)

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)