Kaj Aage Strand, Scientific Director of the US Naval Observatory from 1963-1977, died 31 October 2000 from a stroke at the Manor Care Nursing Home in Washington, DC. He was 93. During a long and distinguished career, he specialized in positional astronomy, especially work on double stars and stellar distances. He was responsible for the design and construction of the Navy's 61-inch astrometric reflector in Flagstaff Arizona, now known as the Strand Astrometric Telescope.
Kaj Strand was born 27 February 1907 on the outskirts of Copenhagen, Denmark. He entered the University of Copenhagen in 1926, majored in astronomy, and graduated in 1931 with Magister (Master's) and Candidate Magister degrees. At the invitation of Ejnar Hertzsprung, during the 1930s he worked at Leiden on a program of photographic double stars; he applied these results toward his doctorate from Copenhagen in 1938. From 1938-42 Strand worked under Peter Van de Kamp as a Research Associate at Swarthmore College, and began the photographic double star program with the 24-inch telescope. During the War he entered the U. S. Army, and then the U. S. Army Air Force, and flew as a Captain and chief navigator on B 29 tests. As head of the Navigation Department he was involved in operational training of special air crews, including the first atomic bomb crew.
After the War, Strand returned briefly to Swarthmore, and in 1946 began as an associate professor at Yerkes Observatory, where he was offered a position by Otto Struve upon the retirement of George van Biesbroeck. In the same year he became chairman of the astronomy Department at Northwestern University, and was responsible for planning the University's new computer center. In 1953 Strand played an important role in an international conference on astrometry held at Northwestern, the second astronomy conference to be sponsored by the newly founded National Science Foundation. The meeting proved to be a landmark in reviving astrometry, leading to the planning of the AGK3R catalog project and the Brouwer astrograph in Argentina, among other activities. Strand again played a seminal role in the Cosmic Distance Scale Conference, held in 1956 at the University of Virginia, where he first proposed a large reflector for the determination of parallaxes of stars fainter than 13th magnitude. This was a bold concept, since parallaxes had only been undertaken with refractors, with the exception of Adriaan van Maanen's work with the 60-inch and 100-inch reflectors at Mt. Wilson.
In 1958 Strand accepted a position as head of the Astrometry and Astrophysics Division at the US Naval Observatory, replacing John S. Hall when the latter became Director at Lowell Observatory. Strand rose to the position of Scientific Director of the Naval Observatory in 1963. Here he was able to bring his concept of an astrometric reflector to fruition; he was primarily responsible for the design and construction of the 61-inch astrometric telescope, dedicated in 1964 at the Observatory's station in Flagstaff, Arizona. The telescope has served as the premier ground-based telescope for stellar distance determination since that time.
Upon his arrival at the Naval ObservatQry Strand also initiated a program of photographic double star observations with the 26-inch refractor. Double star research was one of Strand's specialties, and when at the Astrometric Conference in 1953 he had surveyed the field, he proposed that more emphasis be placed on obtaining photographic observations of wider binaries, while visual observers should be encouraged to observe only the close doubles too difficult for the photographic method. This stemmed from the work of Hertzsprung and others, who had shown that the photographic method was much more accurate than the visual method for binaries with separations larger than 2 to 3 arcseconds. Because the 26-inch had not been modified since 1893, Strand obtained funds from the Office of Naval Research to update the telescope; in 1958 the telescope underwent its largest change in appearance since its move to the Observatory's new site in 1893. Utilizing a photographic camera Strand brought with him from Northwestern, the photographic double star program became one of the long-range programs of the Observatory's Astrometry and Astrophysics Division. It commenced in 1958 and continued until 1981, with almost 11,000 plates taken.
Among Strand's other activities was the establishment of the Naval Observatory's first Southern Hemisphere station at el Leoncito, Argentina. The location of this station was strongly influenced by the fact that Yale University astronomers, under the direction of Brouwer, had dedicated the Yale-Columbia Southern Observatory in 1965 at the same site. The observations, part of the Observatory's commitment to the Southern Reference Star program, were undertaken with the 7-inch transit circle from December 1966 to August 1973.
Strand served as a consultant to NASA, and as a member of advisory boards for the National Science Foundation, Office of Naval Research, National Bureau of Standards and other agencies. Among his honors were the Navy's Distinguished Civilian Service Award in 1973. He was an active member of local, national and international organizations, including the International Astronomical Union, the American Association for the Advancement of Science, the American Astronomical Society, the Philosophical Society of Washington and the Cosmos Club.
Dr. Strand is survived by his wife of 51 years, Emilie Rashevsky Strand of Washington, and two daughters, Dr. Vibeke Strand of Portola Valley, California, and Kristina Ragna Strand of Marshall, North Carolina. A detailed oral history interview, conducted by David DeVorkin and Steven Dick, is deposited at the US Naval Observatory Library.
Photograph courtesy of the US Naval Observatory