Publications of the Astronomical Society Of

PUBLICATIONS OF THE

ASTRONOMICAL SOCIETY OF THE PACIFIC

Vol.63 June 1951 No. 372

AN ASTRONOMICAL VISIT TO SOUTH AFRICA

John. B. Irwin Goethe Link Observatory, Indiana University

During the summer of 1950 the writer had the privilege of making photoelectric observations at three of the South African observatories with the capable assistance of Arthur N. Cox, a graduate student at Indiana University. During the four-month stay in the Union, visits were made to four other observatories. Thanks to the speed of modern air transportation, it is possible for a university professor to spend his "summer vacation" in the fabulously clear African winter observing the still comparatively neglected skies of the southern hemisphere. I am indebted to the Office of Naval Research for the grant that made this research possible and to the Graduate School of Indiana University which supplied me with such an efficient assistant. Johannesburg is some 9,700 miles and 47 hours by air from New York as Pan American flies it via Lisbon, Dakar, and Leo- poldville. The Constellation Clipper "Yankee Ranger" lifted us off the LaGuardia runway at noon on May 29 and after six inter- mediate stops deposited us at the Palmietfontein Airport of Jo- hannesburg at 7:23 p.m. Springbok (South African) Time on May 31. Disembarking from the plane we turned around and looked upward, drinking in for the first time the superb southern Milky Way, the Southern Cross, Alpha and Beta Centauri, the Carina star cloud, and the Magellanic Clouds. The next morning, after breakfast, where a choice of cereal p- was made between Jungle Oats and Mealie Meal, we visited the ^ Yale-Columbia Southern Station on the attractive campus of the rl. University of Witwatersrand. Here amid the eucalyptus trees we s') met Professor Cyril Jackson and his charming wife and inspected the 26-inch photographic refractor, which ranks with the long-

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focal-length refractors at the McCormick, Allegheny, and Cape Observatories in the number of stellar parallax determinations. This telescope was installed at the instigation of Professor Schles- inger in 1925 under the vigorous direction of Dr. Harold S. Alden. The aluminum-alloy tube, thirty-six feet long, is mounted inex- pensively in a high, narrow building with two sliding roof panels in such a way that observations must be made on, or very close to, the meridian. A five-inch Ross lens of eighty-inch focal length, mounted on the tube of this large refractor, is used as a catalogue camera, supplying the plates for the Yale photographic reobserva- tion of the A.G. zones from +9° to —30°. Dr. Paul Skoberla, who before the war was astronomer at the now abandoned Breslau station at Windhoek in South West Africa, assists Professor Jackson in the operation of this station. At present, much of the time of these two astronomers is taken up in preparing for ship- ment tens of thousands of astronomical plates which are being sent to New Haven. Johannesburg is a city of almost a million population and, in some respects, it could be likened to a pocket edition of New York. Its phenomenal growth and industrialization since its founding in 1886—and especially in the past decade—has so befouled the high veld skies that exposure times, even with modern fast plates, are as much as twice as long as they were ten or fifteen years ago. With diminishing returns from the parallax program becoming apparent, the Observatory has branched out into other fields, no- tably that of photoelectric photometry. This type of astrophysical research requires not only the clearest possible skies but also a more flexible type of telescope mounting. It is indeed fortunate that the 26-inch refractor can be provided with a new "home" which meets these more stringent requirements. Later in Sep- tember, on the morning of my final departure from Johannesburg, the local newspaper carried a story telling of the future move of the Yale-Columbia station to Mount Stromlo, Australia, on the invitation of Dr. R. v. d. R. Woolley, director of the Common- wealth Observatory. A new dome and mounting for the 26-inch will be provided, as well as housing for the astronomical staff. Canberra, a city of some fifteen thousand population, has a recent law forbiding its industrialization or residential expansion.

Dr. A. D. Thackeray, the new director of the Radcliffe Observ- atory, kindly drove down the thirty-six miles from Pretoria to take us back with him. Before leaving, however, we visited the Union Observatory, located some three miles east of the Yale- Columbia station halfway up Hospital Ridge. This Observatory was first founded as a meteorological station after the Boer War under the directorship of R. T. Α., Innés, becoming the Union Observatory in 1912 ; a 26^-inch refractor was obtained after the first World War. Here we met the director. Dr. W. H. Van Den Bos, noted for his observations of double stars. The Observatory, with the aid of two quartz-crystal clocks, supplies a time service to most of South Africa. At the time of our visit a new faint aster- oid, which had been picked up near the south celestial pole by E. L. Johnson, was being eagerly followed because a preliminary orbit indicated an extraordinarily short period. The 10-inch f/4.5 Franklin-Adams star camera with 15-inch square plates is an ideal instrument for discovering new asteroids and comets. It has no device, however, such as the one attached to the finder of our 10-inch Goethe Link camera, whereby the motion of faint objects can be accurately set off, enabling the plate to record very faint asteroids and comets. The Leiden Observatory Southern Station is on the grounds of the Union Observatory; its equipment consists of the twin 16-inch Rockefeller refractor, each objective of 90 inches focal length. The telescope has now been converted to photoelectric photometry, a 1P21 photometer having been attached to one "barrel." We met and talked "shop" with Dr. A. J. Wesselink, the Leiden observer, who is noted for his superb photographic photometry of eclipsing variables. We also met the assistant director of the Leiden Observatory, Dr. P. Th. Oosterhoff, who was spending a number of months in the Union measuring photoelectric colors of the southern Β stars, with additional observing time on the 74-inch Radcliffe reflector. Wesselink has since become the chief assistant at Radcliffe, his place at Johannesburg being taken by Dr. Th. Walraven. The Union Observatory, because it is some one hundred fifty feet higher than the Yale-Columbia Southern Station and somewhat farther away from the railroad yards and downtown Johan-

nesburg, has somewhat the better photoelectric observing con- ditions, although not what one might reasonably expect at an altitude of 5800 feet. Present hopes are that the Union Observa- tory can be relocated away from Johannesburg's smoke, and a site some thirty miles northwest of the city and twenty miles west of Pretoria, near Hartebeestpoort Dam, is being seriously con- sidered. There are also hopes of acquiring a new 74-inch reflector. The Leiden Southern Station will probably be moved to the new site also. Leaving Johannesburg we found the hour's drive to Pretoria along the well-paved national highway one of great interest. The countryside with its rolling brown fields and towering eucalyptus trees reminds one very strongly of parts of California, although the many natives afoot or on bicycles, the Afrikaans-English road signs, the left-hand driving on the highway, the distinctive types of architecture, all reminded us that this was indeed a foreign country. Soon after the distant view of the Voortrekker Monu- ment atop a small hill just south of Pretoria warned us that our long trip was nearly over, the aluminum-painted Radcliffe 74-inch turret became visible on Waterkloof Ridge to the right of the main highway. A few miles more over a red dirt road winding upward through eucalyptus, wattle, and protea brought us to the Observatory entrance and paved roads again. Four nights later, with the expert assistance of Director Thackeray and bushy- haired Dr. David Evans, we were hard at work on our photoelectric program. The Radcliffe Observatory was first established in Oxford, England, in 1771 and was transferred to its present site in 1937. The 57-acre site, a gift of the municipality of Pretoria, is just over 5000 feet above sea level and is some four air-line miles from the center of this rapidly growing city of a quarter of a million. The view to the north is over the near-by eastern Pretoria suburbs of Muckleneuk, New Muckleneuk, and Waterkloof, while seven miles to the west the furnaces of the large Iscor steel works occasionally light up that whole section of the sky at night. The view to the south is, however, over open veld with the lights of Johannesburg just visible on the far horizon. The region south of the zenith (δ = —25° 477) is, of course, the critical one; in

fact, when I asked one of the astronomers how the telescope be- haved north of the zenith he replied that he couldn't remember ever having used it there. The Observatory grounds could be described as a little bit of England transplanted to Africa. The three residences for the astronomers and the well-equipped office building which contains a very excellent library are of attractive brick design with shingled roofs ; the gardens about the director's home are especially beautiful. A small "Monastery" is now being built which, with a newly acquired Jeep station wagon, should make the stay of visiting astronomers both efficient and com- fortable. As it was, we stayed at a modern private hotel near the center of the city, where $38 a month included excellent four- to six-course meals. A 1938 Dodge, bought at perhaps a 50 percent greater price than one would pay at home, provided us with the necessary mobility.

Fig. 1.—The 74-inch Radcliffe reflector, Pretoria.

Although the various buildings, the 61-foot cylindrical turret, and the mounting were all completed in 1938, it was only in 1948 that the completed mirror was delivered and installed. All work, including the programs of Thackeray and Evans for low-disper- sion spectroscopy and direct photography, was then done at the

30-foot Newtonian focus, but by this time the Cassegrain spectrograph has been received and is probably in full-time operation. The telescope is precision mounted and driven; the observing carriage is very convenient to use, and with an assistant "down- stairs^ to make the gross settings it is possible to shift rapidly and accurately from object to object. Precision guiding is accomplished with the aid of a double-slide plate holder that is remarkably smooth of operation and free of backlash. Observation at the Cassegrain focus may be somewhat inconvenient because there are no rising platforms, such as have been found most useful at McDonald, for example. There is provision for work at the coudé focus with a focal length of 173 feet, although at present no coudé spectrograph is in prospect. If a coudé grating spectrograph were available, similar to the one now installed at Palomar, there is no question but that the spectroscopic attack on the southern skies would be greatly strengthened. The winter Transvaal skies are almost invariably clear, although we experienced short stretches of "unusuar" weather that even included a thunderstorm. The winter nights were surprisingly warm for such an altitude; the temperature at night was usually between 50 and 60 degrees, only once dipping below 40 degrees. The seeing was good to excellent early in the evening, but after midnight often became worse with the advent of a moderate southerly breeze. A series of intensive observing sessions was concluded with a welcome three-day vacation in the Kruger National Park Game Reserve 250 miles away. This park came up to all expectations and is a "must" for any visitor to South Africa. Our hosts, Mr. and Mrs. Matt Maré of Pretoria, who had spent two semesters at Indianâ University a few years ago, entertained us with the far- famed Afrikaans hospitality. Returning to Pretoria, we packed our equipment into the back of the Dodge and drove 300 miles south to Bloemfontein where the 27-inch Lamont-Hussey visual refractor had been made available to us through the kindness of Dr. Leo Goldberg and Dr. R. A. Rossiter of the University of Michigan. This Observatory, completed in 1928, is in the center of Bloemfontein but is a few hundred feet above the rest of the city, being on top of Naval Hill, and so located that neither the city nor its lights can be seen from

. © Astronomical Society of the Pacific · Provided by the NASA Astrophysics Data System AN ASTRONOMICAL VISIT TO SOUTH AFRICA 117

the telescope. Surrounding the Observatory is the Franklin Game Reserve where it is common to see numbers of zebra, eland, bles- bok, or even fifty or more of the beautiful but shy springbok. Pro- fessor Rossiter has been uncommonly successful in discovering new visual binaries with the 27-inch, the largest refractor in the southern hemisphere. His program of late has been emphasizing

Fig. 2.—The Lamont-Hussey Observatory, Bloemfontein.

the remeasurement of double stars closer than OVS discovered at the Observatory, especially those suspected of orbital motion. The night sky is so dark that Karl Henize, a University of Michigan graduate student who is surveying the southern skies with the 10-inch f/4.5 Mount Wilson camera with objective prism, is able to make exposures of five hours' duration. This beautifully mounted telescope is located in a small building with sliding roofs separate from, but near to, the main building. Karl returned by plane from a "refresher" visit to the States a few days after our arrival in Bloemfontein. He has established himself in a room in the main building and has set up a darkroom and the necessary equipment to process and search the large photographic plates taken with the 10-inch. During the daytime he captains the Orange Free State baseball team, introducing the sports-loving South

Africans to the mysteries of the American game and being in- itiated by them in return into the none too subtle hazards of rugby. Our own polarization program ran into long and unseasonable spells of cloudy weather during our six-week stay, but results of value were obtained. We were greatly helped at the start by Dr. Rossiter, who put in long hours making the telescope ready for our photometer. Through the kind efforts of Dr. Bok a very nice house, with cook attached, was located for the month of August. The Boy den Station at Harvard Kopje near Mazelspoort is clearly visible from the top of Naval Hill. We made the thirty- mile round trip three times, making the acquaintance of the work- ing staff, inspecting Ivan King's photoelectric photometer on the 60-inch, viewing the 24-inch Bruce photographic doublet and the many other historic instruments located there among the pines. Under the able administration of Dr. John Paraskovopoulos and with its many well-kept-up instruments at a location that is un- doubtedly better than that of any of the other South African observatories, Harvard Kopje is an irftpressive place for an astronomer to visit. Since our departure the Bruce has been "put out to pasture" and the ADH 32-36-inch flat-field Baker-Schmidt camera is now in action on the Bruce mounting. At the time of our stay, Bloemfontein was the mecca for all American astronomers in South Africa; we particularly enjoyed the hospitality and many visits and chats with the Boks. During a cloudy spell early in August, Karl Henize, Art Cox, and I managed a two-day trip to the Maluti Mountains, some 125 miles east of Bloemfontein in the wilds of Basutoland ; later, at the end of our stay, we three had a memorable four-day camping trip that took us to the top of Champagne Castle on the Natal-Basutoland border, one of the highest peaks in the Drakensberg. Returning to Pretoria was akin to returning home. Aided by clear skies, we finished our 74-inch program in the first two weeks of September, packed up our equipment, regretfully said good-bye to our many friends, and took the train to Capetown, 1000 miles to the south and west. Noon of the second day we had a short stop at Worcester, some 110 miles north of Capetown, where, over forty years ago, Professor Solon Bailey of Harvard spent a

number of months of observing as part of a systematic test of the quality of the South African skies. My two weeks in Capetown were busy ones ; our photometer was mounted on the 24-inch photographic Victoria refractor in two days' time. This was in preparation for Cox's four-month stay at the Royal Observatory. Six nights of observing were accomplished. The 24-inch, a gift of Frank McClean at the turn of the century, was made available to us through the generosity of H.M. Astronomer, Dr. R. H. Stoy. It is well mounted and driven, has a rising floor, and with a little practice can be set with the unusual accuracy of a second or two of time in right ascension. The dome rotates one complete revolution in a minute and it is possible, for example, to compare photoelectrically stars on opposite sides of the zenith with unusual efficiency. Although Sir David Gill has written that the telescope was named after Queen Victoria, the Observatory tradition has it that it was named after the aster- oid Victoria, the minor planet that played a major role in Gill's very accurate determination of the solar parallax. Since 1926, under the supervision of the recently retired H.M. Astronomer, Dr. J. Jackson, this telescope has been used to determine the parallaxes of over 1500 southern stars. The Royal Cape Observatory, founded in 1820 and maintained since that time by the British Admiralty, has had an unusually brilliant and interesting record in various fields of astronomical discovery and measurement. The Observatory has not only been especially interested in the solar parallax but has made immense fundamental contributions to our knowledge of the positions, proper motions, and distances of the southern stars ; its impact on other sciences in southern Africa has not been negligible. More recently, Stoy, in collaboration with Redman and assisted by Cousins, Menzies, and others, has expanded the work of the Ob- servatory into still another fundamental—and increasingly important—field, that of stellar photometry. In connection with this work it is obvious that the Observatory badly needs a new observing station reasonably close to Capetown but free of its haze and smoke. The last major acquisition of equipment was that of the Victoria refractor some fifty years ago ; it is to be hoped that funds may be made available in order that this large, active, and success-

ful Observatory may proceed with its task with the aid of some modern instrumental equipment. Thanks to the hospitality of the Stoys, trips were made to many historic spots in the beautiful Cape countryside, including visits to the Rhodes Memorial, the Lion's Head, the Tygerberg, the University of Capetown, Stellenbosch University, and Knox- Shaw's new home in Elgin. We attended a meeting of the Astro- nomical Society of South Africa, and, of course, we climbed Table Mountain. On September 26 the leisurely nineteen-day trip home was started, a j ourney that included visits to a number of Euro- pean observatories. The never-to-be-forgotten flight up central Africa was made by flying boat ; and strangely enough, the Atlan- tic was crossed by land plane. In conclusion, two points concerning the South African observatories and their relation to American astronomy need em- phasis. The first is that the American observatories in Africa have been brilliantly successful in accomplishing those things which they set out to do ; and second, these observatories have been run "on a shoe string" and have been seriously undermanned. In a recent poll of fifty-five astronomers asking their ideas concerning "the shape of things to come" in astronomy, Struve states :1 "nearly one-half of the replies urge that more effort be made in the southern hemisphere ..." It seems to the writer that the situation has changed radically in the past ten years in that modern transportation has become extremely rapid and is comparatively inexpensive, especially as compared with the skyrocketing cost of scientific instrumentation. The instruments are there to use and are now easy of access, the weather is remarkably good, and the southern skies—with our two nearest extragalactic neighbors, the southern Milky Way, and countless unusual and important objects—are almost untouched both spectroscopically and photo- elect rically.

1 Journal of the Franklin Institute, 251, 13, 1951.