Clayton Albert Smith (1934–1993)

After a long fight against prostatic cancer, Clayton A. Smith died on May 27th, 1993. His illness was first diagnosed in the early 1980’s, but a combination of his otherwise good health, careful medical treatment and a long determination on his part to remain active as long as possible gave Clayton many additional years of productive life.

Clayton was born in Champaign, Illinois on June 10, 1934. He was the son of Clayton A. Smith Sr. and Marcia Marie Hanke Smith. He attended the Roald Admundsen High School in Chicago, graduating in 1952. Clayton secured a position with Time, Inc., and under Time’s Education Benefit Program was able to attend the University of Chicago. He completed a BA in 1956 and a BS in Physics in 1957.

After two years of graduate work at Chicago he obtained a position as an astronomer in the Seven-Inch Transit Circle Division at the US Naval Observatory. At the time the division was heavily engaged in the observation and compilation of the 21,500 reference stars for the AGK3 (AGK3R). This was a large international effort involving twelve observatories. Clayton very quickly assumed a key role in combining the data of the contributing observatories, this work resulting in the AGK3R catalog in the late 1960’s.

During the mid to late 1960’s Clayton also completed his graduate work. He was awarded his PhD in Astronomy by Georgetown University in February 1969. His dissertation was “A Catalog of Positions and Proper Motions of 310 Stars in the Regions of Taurus and Orion” in which he developed new methods of combining observational data to determine stellar proper motions.

Clayton was also involved in the planning of the Southern Reference Star program (SRS). This involved the USNO 7” Transit Circle at El Leoncito, Argentina as well as nine other observatories, and the SRS is the southern counterpart of the AGK3R. The program started in 1966, and Clayton was director of the station from 1968-1970. During that time some 75% of the program’s observations were made.

After returning from Argentina Clayton devoted himself to the compilation of the El Leoncito observations. Early in the observing program he saw the value of a suggestion to observe the minor planets and to make fundamental azimuth observations. This made it possible for him to develop a procedure to compile the observations into an absolute catalog (WL-50), which consequently made a valuable contribution to the system of the FK5 in the Southern Hemisphere. Clayton completed the WL-50 in 1981.

From 1980 to 1988 Clayton headed the effort to complete the SRS project. This was done in collaboration with colleagues at the Pulkovo Observatory in the Soviet Union. When the SRS was completed it, in combination with the AGK3R, formed a reference system of stellar positions covering the whole sky with a density of about one star per square degree which has come to be known as the International Reference Stars (IRS). The importance of the IRS can be seen from the fact that it constitutes almost 40% of the Hipparcos program.

In the early 1980’s Clayton realized that a fundamental catalog larger than theFK5 should be compiled independently of the previous fundamental catalogs. The result is the Washington Fundamental Catalog (WGC) project that is due to be finished in 1997. Clayton very much wanted to see the completion of the WFC, but he did establish the project concepts and guidelines under which the work is proceeding.

Clayton was active in the IAU for many years. He became a member in 1979 and belonged to Commissions 8, 20 and 24. In 1991 he was elected Vice-President of Commission 8 and was due to become its president in 1994. He was very active in organizing IAU Colloquium 127, Reference Systems. This important assignment brought together such diverse areas of astronomy as radio astronomy, astrometry, time, Earth Rotation and celestial mechanics to formulate a consistent approach to the question of how positions of celestial objects should be defined and measured.

Clayton was unusually popular among his co-workers and professional colleagues. His competence, unassuming manner, and willingness to share his considerable knowledge made him the kind of person that everyone found approachable and receptive. Clayton liked nothing better than to help a more junior member of the staff understand the complexities of astrometry, and he consequently leaves behind a considerable legacy of knowledge. One indication of the high regard in which he was held came shortly after his death when the staff at the Felix Aguilar Observatory, El Leoncito, name Minor Planet 3118 for him. Clayton loved theater, opera and concerts and shared this love with his many friends by inviting them to performances. He was kind and considerate to all he met, and he will be missed by all who knew him.