Boyden Observatory  [A Concise History]

By A.H. Jarret, PH.D.

Department of Astronomy, University of the Free State

Part of an article which appeared in the University of the Free State' s journal “Acta Academica”

Nr. 12, 1979

"Hanover, which was the first seriously considered site for an observatory".......  after Arequipa, Peru was found to be unsatisfactory....

The history of Boyden Observatory covers nearly a century, of which for over 50 years it has been at its present site at Mazelspoort.

In 1879 Uriah A. Boyden, who was a mechanical engineer of Boston left in his will a sum of $238,000 to Harvard College for the express purpose of carrying out astronomical observations at such an altitude as to minimize so far as possible the troublesome effects of the earth’s atmosphere. In 1887 it was transferred by the trustees of the fund to the President and fellows of Harvard College for the use of the observatory.  The Director of Harvard College Observatory at that time, Prof. Edward C. Pickering, was very keen to build a southern hemisphere observatory. The establishment of the Boyden Fund made this a possibility.

At his instigation one of the Harvard Observatory staff, Prof. Solon I Bailey visited South America in 1889 for the purpose of making preliminary studies for the selection of a station for observations of the southern sky.  As a result of these studies Arequipa , Peru , was eventually chosen at the site for the permanent station and the equipment was moved to Arequipa in October 1890. During January 1891, Prof. Pickering arrived in Arequipa along with the 33 cm Boyden telescope and several smaller instruments.   Arequipa was found to have a very steady atmosphere which made it particularly favourable to using high magnification s for the study of faint planetary details. Conditions were also extremely good for double star observations.

Prof. Bailey wrote that although Arequipa proved to be a fairly satisfactory site from the point of view of the results obtained there it was indisputable that the amount of cloud was often considerable and its distribution inconvenient. Thoughts were accordingly given to moving the station somewhere else in the southern hemisphere.

The excellent climatic conditions of South Africa were fairly well known and had already been brought to the attention of the Director of Harvard Observatory by Sir David Gill. Unfortunately cloud records were very few and no observations at all seemed to have been made concerning the steadiness of the transparency of the atmosphere. Accordingly an expedition was sent to South Africa in 1908 under the leadership of Prof. Bailey to investigate the possibilities.

The expedition travelled via Cape Town and Worcester to Hanover , which was the first seriously considered site for an observatory. Then Bloemfontein and Kimberley were also visited. The expedition penetrated as far north as Bulawayo but it was realised that cloudiness and rainfall increased the further north one went.

Having made a provisional survey of the entire region it was decided to fix upon a site for the main station. Hanover was selected, primarily because in the opinion of Sir William Morris who had made observations for geodetic purposes in the region, it offered the best conditions. This viewpoint was also shared by Dr. RTA Innes, the then Director of the Johannesburg Observatory.   Bloemfontein and Worcester were decided upon as secondary stations.

Systematic testing commenced at Hanover early in February 1909, a small observatory being established at the edge of town. The instrumentation consisted of a 20 cm visual telescope, a 13 cm visual telescope and a small photographic instrument. At all the stations equatorial stars were photographed each clear night as a test of the transparency and steadiness of the atmosphere. Exposures were also made for several hours on polar stars as a check on the cloud conditions. Approximately 1 500 photographs were obtained from the three stations.

An interesting conclusion from the observations was that there was very little difference in the night cloudiness between Worcester , Hanover and Bloemfontein . However, it was noted that the cloudy and rainy season for Hanover and Bloemfontein is in the [southern] summer whereas at Worcester this was not the case.  This of course might be expected since Worcester is located between Cape Town and the Karoo . Cape Town ’s cloudy season is in the [southern] winter whereas the towns in the Karoo have their cloudy season in the [southern] summer.

A large diurnal range of temperature was evident at the three sites. During this time it was found very advantageous to make observations from one of the koppies in the neighbourhood of Hanover – the diurnal range of temperatures was significantly reduced (being about 4° Celsius less than that on the surrounding plains).

As regards the steadiness of the atmosphere or seeing as it is called, it was found that there was very little difference between Hanover and Bloemfontein , Worcester being somewhat inferior in this respect. Again there was very little difference between Hanover and Bloemfontein in the transparency of the atmosphere: it was definitely superior to the experienced at Worcester .

The conclusion of the site testing expedition was that Hanover and Bloemfontein appeared to be more or less equal from the astronomical standpoint. Although the seeing may be a little better at Hanover it does seem from all consideration that Bloemfontein was preferable and Prof. Bailey goes on to say “that it is probably not surpassed by any other locality in South Africa as a site for an astronomical observatory”.

Dr. Shapley made the decision to move the Arequipa station to South Africa and in February 1927 the instruments were shipped to Bloemfontein .  Dr. and Mrs. Paraskevopoulos arrived at Bloemfontein in July 1927. They inspected several possible sites in the area and finally decided on a koppie overlooking Mazelspoort some 25 km northeast of Bloemfontein .  Observing work commenced in September 1927 but it was not until 1933 that the initial instrumentation was complete. 

Under the auspices of the Boyden Council the observatory flourished as is evident from the several hundreds of publications emanating from the establishment in most of the international astronomical journals.  The owners then of the Boyden Observatory (the Centre of Astrophysics comprising the former Harvard College Observatory and the Smithsonian Astrophysical Observatory) announced that they would be willing to give the observatory to any organization prepared to take it; in particular they hoped that the University of the Orange Free State would see their way to accepting the gift of the observatory for its department of astronomy. In April 1976 the University Council announced that they were prepared to accept the observatory.

From its earliest days the research activity at Boyden has encompassed photographic and photoelectric observations of stars and star fields in the Southern Milky Way, the Magellanic Clouds and Southern hemisphere variable stars. Located 29 degrees south of the equator, Boyden is ideally suited for studies of the centre of our galactic system and the and the Magellanic Clouds.

The association with the University of the Orange Free State has led to additional research fields, including studies of flare stars and hydrogen emissions from nebulae, the Sun and interplanetary space. Some forty publications on flare stars have been made over the past decade as part of a cooperative research programme under the auspices of the International Astronomical Union.

Hydrogen emissions from solar prominences have been examined over the past few years with emphasis on the part they play in energy transfer processes from the solar interior to the outermost regions of the solar atmosphere.