Harold Lee Alden, American astronomer, was the son of Reverend David Adonijah Alden and his wife Emily Elizabeth, born Worcester. He qualified in 1912 as Bachelor of Arts (AB) at Wheaton College, a Christian institution in the state of Illinois. The next year he obtained the degree Master of Science (MS) at the University of Chicago and in 1917 a PhD at the University of Virginia in Charlottesville. He started his career in 1912 as an assistant in the photographic photometry programme at the Yerkes Observatory, which at that time had the largest telescope in the world and where he remained to 1914. He then moved to the Leander McCormick Observatory of the University of Virginia at Charlottesville, where he remained for eleven years. Towards the end of World War I (1914-1918) he served as director of the School of Navigation of the U. S. Shipping Board in Jersey City. During his time at McCormick Observatory he was appointed also as associate professor of astronomy at the University of Virginia in 1924 and the next year was elected a Fellow of the Royal Astronomical Society (FRAS). He was a hard worker and an indefatigable observer and acquired a steadily rising reputation in the field of photographic astronomy.

Alden came into contact with the director of the Yale University Observatory, Dr Frank C. Schlesinger, who visited South Africa in 1923 to secure a site on which he wished to established the Yale Southern Station for the study of parallaxes and proper motions of stars in the southern hemisphere. A suitable site was selected in the grounds of the University of the Witwatersrand. Instruments for this observatory were installed in 1924 and that same year Alden accepted an appointment as its director. He arrived in 1925 to supervise the erection of the instruments. These included a 660 mm photographic refractor with a focal length of 11 meters and with a 250 mm visual telescope. In 1931 a special celestial camera with a 127 mm aperture was added. With these facilities and a small staff Alden started a programme of systematic star photography of the entire southern skies, a project to which he devoted himself conscientiously and persistently for some 20 years and which produced over 60 000 photographs that represented over 250 000 separate exposures. The data were used mainly to determine the parallaxes and proper motions of southern stars. In addition he studied some astrometric double stars (with invisible companion stars), the light curves of long period variable stars and the motions of some of the satellites of Jupiter, Saturn and Nepture and of minor planets. Many of his results, including 1323 parallax determinations, were published in "The probable errors of Yale parallax plates" in the Transactions of the Astronomical Observatory of Yale University (1949, Vol. 15, part 2). His results were also reported in well over 100 scientific papers.

Alden was a popular figure in the Johannesburg community and his house became an active center of social life. He contributed to the proceedings of the South African Association for the Advancement of Science, served as president of its Section A (which included astronomy) in 1931 and published papers on "The apparent orbit of a spectroscopic binary" (1929), "The year's progress in astronomy" (1930) and "Night cloudiness in Johannesburg" (1933) in the association's South African Journal of Science. Also published locally were his "Photographic observations of comet 1927c (Pons-Winnecke)" (Circular of the Union Observatory, Johannesburg, 1929). He was an honorary member of the Astronomical Association of South Africa and served as its president for 1931-1932. He was a member also of the South African National Committee in Astronomy, vice-president of the American Association for the Advancement of Science and chairman of its Section D (Astronomy) in 1951, and president of Commission 24 (Stellar Parallaxes) of the International Astronomical Union from 1952 to 1955. As a dedicated observing astronomer he made a lasting contribution to precision long-focus photographic astronomy. A crater on the far side of the moon was named after him in 1970.

In 1945 Alden returned to the United States and became professor of astronomy in the University of Virginia and director of its Leander McCormick Observatory, appointments he held to his retirement in 1960. Cyril Jackson, a South African, succeeded him as director of the renamed (in 1946) Yale-Columbia Southern Station, until the station was moved to Canberra, Australia, in 1952. Alden married Mildred Viola Davidson in 1917. He was survived by his wife, a son and two daughters.

List of sources:

Dictionary of South African biography, Vol. 4, 1981.

Google scholar. http://scholar.google.co.za/ , publications by H. L. Alden.

Jarrett, A. H. American observatories in Southern Africa. South African Journal of Science, 1986, Vol. 82, pp. 11-13.

Long, A. W. The foundation and development of the Astronomical Society of South Africa. Journal of the Astronomical Society of South Africa, 1930, Vol. 2(4), pp. 153-180.

Obituary: Professor Harold L. Alden. MNASSA, 1964, Vol. 23 (1 & 2), p. 2.

Rosenthal, E. Dr Harold Lee Alden. MNASSA, 1971, Vol. 30(1 & 2), pp. 4-5.

South African Journal of Science, 1937, Vol. 34, pp. xiv-xix: Presidents and secretaries of the sections.

Standard Encyclopaedia of Southern Africa (SESA). Cape Town: NASOU, 1970-1976.

Van de Kamp, P. [Obituary]: Harold Lee Alden. Quarterly Journal of the Royal Astronomical Society, 1964, Vol. 5, pp. 291-293. Retrieved on 1 September 2022 from https://articles.adsabs.harvard.edu//full/1964QJRAS...5..291V/0000293.000.html

Compiled by: C. Plug

Last updated: 2022-09-01 11:38:08