Solar Observatory (Brukkaros)
1925 – 1931

Current Information:
Current  Information:
The  Observatory has closed down. The Current Information section is not relevant to this Observatory.
Altitude: 1510 m (4 955 ft ) above sea level.

In Brief:

Noted  for:

This Observatory was created in order to determine the Solar Constant. (The amount of energy the Earth receive from the Sun.) The Astrophysical Observatory of the Smithsonian Institution in Washington set up the site in 1925. However the atmosphere over Mount Brukkaros in Namibia turned out to be too dusty to make accurate observations and in 1931 the Observatory was closed down and moved to Mount St. Katherine in Egypt.

Historical background:
The Astrophysical Observatory of the Smithsonian Institution in Washington was founded in 1890 by Samuel P. Langley. He believed that careful study of the variations in the Sun’s energy output might enable one to forecast the weather and / or climate some time in advance. Therefore detailed observations had to be made of the Solar Constant. (That is to determine the amount of solar energy available outside the Earth’s atmosphere at mean solar distance.)
In order to compliment the Astrophysical Observatories observations and to allow for local atmospheric losses, observatories were established at high altitude sites. The network consisted of a site on Mount Montezuma at Chile. A site was set up at Mount Harqua Hala in Arizona, but later moved to Table Mountain in California.  A third site was set up Mount Brukkaros in South West Africa (Namibia) which was later moved to Mount St. Katherine in Egypt.
Charles G. Abbot selected the sight in South West Africa, on Mount Brukkaros, an extinct volcano rising high above the surrounding desert regions. A grant from the National Geographic Society in 1925 enabled the sight to be developed. (Note: Smits refer to National Geographic Society and Moore to Royal Geographic Society in London)
The first team at the site was site director William H. Hoover, accompanied by a Miss Johnson whom he later married, and Frederick A. Greeley as his assistant. No observations took place as the site was still developed.
The observatory consisted of a tunnel 3m (10 ft) wide, 2.2m (7 ft) high and 10m (32 ft) deep, excavated in the side of the mountain. A coelostat was mounted on a platform in front of the tunnel feeding sunlight to the instruments in the tunnel. Instruments included a spectograph(to take a light spectrum of the sun) and a bolometer (measuring the intensity of radiation across the spectrum).
Hoover and Greeley was replaced in 1929 by Louis O. Sordahl and A. G. Froiland. Froiland left in 1931 and was for a short while replaced by Mr. (later Professor) Arthur Bleksley.
Observations started on 9 December 1929. Unfortunately it was too windy. The haze due to windbourne dust made atmospheric corrections uncertain and therefore the measurements were not accurate enough. Static electricity due to the dry air played havoc with the instruments.
The Observatory closed down in December 1931 and was moved to Mount St. Katherine in Egypt in 1932/ 33. (Note that Moore refer to the operational time as from October 1926 to June 1932.)

William H. Hoover. He was first astronomer.
Frederick A. Greeley
Louis O. Sordahl
A. G. Froiland
Mr. (later Professor) Arthur Bleksley.



Link to the Telescope Manufacturers.

Coelostat: No information available.
Spectograph: No information available.
Bolometer: No information available.


Pictorial  Sources:

Smits, P., A Brief History of Astronomy in Southern Africa. (Unpublished)
Moore, P. & Collins, P., Astronomy in Southern Africa, p.142. (General Source)