John B. Irwin died of lymphoma cancer in Tucson, Arizona on 20 April 1997. He was born in Princeton, New Jersey, on 7 July 1909, the son of Frank and Mary (Barrows) Irwin. His father was later professor of mathematics at University of California, Berkeley. He attended elementary and high schools in Berkeley and received a BSc in mechanical engineering in 1933 and his PhD in astronomy in 1946 from UCB. Much of his graduate work was done at Lick Observatory, starting in 1941, under the direction of Art Wyse and Director William H. Wright, using the Kron photometer to study eclipsing variables.
Irwin's first jobs were with United Airlines operations at several airports in the midwest, especially Iowa City. With his minor in astronomy, he got a job at the US Naval Observatory for 1937-38 before returning to UCB to continue graduate school. He joined the AAS at the Christmas meeting on 29 December 1937 and was an active participant in AAS meetings until very late in his life. He served on AAS Council from 1958 to 1960 and was also a member of the American Association for the Advancement of Science and the International Astronomical Union.
During the war years, Irwin's knowledge of mechanical engineering was useful for rocket research for the Navy done with Ira Bowen and Willy Fowler at Caltech and later in the desert at Inyokern. He helped Bowen develop rapid framing cameras to photograph rocket flights, which were later used for fireball photography in the nuclear weapons program at Los Alamos. Returning to UCB after the war, he focussed on the eclipsing variable star U Sge and succeeded in a direct measurement of limb darkening as one star passed behind the other. The results were published in the Astronomical Journal.
His subsequent career took him to the University of Pennsylvania (Asst. Prof. 1946–48) and Indiana University (Assoc. Prof. 1948–51, Prof. 1951–64). He visited South Africa in 1950, obtaining photoelectric colors of globular clusters from Pretoria, Bloemfontain, and Cape Town. Another visit to South Africa in 1955, under a Guggenheim Fellowship, allowed him to work on southern Cepheids. He moved to a staff associate position at the Carnegie Institution of Washington for 1964–67. During that time, he and his wife Ruth lived in Chile, and he participated in the initial site selection for the observatory at Cerro Las Campanas and for the observatory now being built at Cerro Pachon. He was a visiting resident professor at Steward Observatory 1967–68, at UCLA 1968–70, and an associate professor at Kean College, New Jersey from 1971 until his retirement in 1977. The picture, taken at Las Campanas in 1977, shows Irwin in his guise as a site surveyor.
Although Irwin's primary scientific research lay in the areas of photoelectric photometry, binary star orbits, Cepheid variables, and the history of astronomy, he also foresaw the astronomical impact of modern computers and reported on EDVAC in the Publications of the Astronomical Society of the Pacific in 1948. His 19 popular articles in the Griffith Observer, written between 1973 and 1992, remain great reading, even for professionals.
A striking result of his interest in Cepheid variables came when he realized in 1955 that the distance scale of the universe could be made more precise by measuring the distance to galactic open clusters with Cepheid members. The first one found was S Nor in NGC 6087. While still at Cape Town, he discovered U Sgr in M25, and later extended the list to at least nine more examples in work with Robert Kraft at Indiana. Results were published in Astrophysical Journal Supplement, vol. 6.
Irwin had been retired in Tucson for 20 years, where he enjoyed his ham radio and stamp-collecting hobbies. He was an active member of Northminster Presbyterian Church and the Southern Arizona Hiking Club, for whom he led more than 100 hikes, served as president and program chairman, and instituted lists of mountain peaks for “peak baggers.” Mount Whitney, in the Sierra Nevadas of California, was one of his favorites, and he climbed to the summit many times, including celebrations on his 80th and 85th birthdays.
John Irwin's first wife, Ruth Catherwood Irwin (m. 1936), predeceased him in 1991. He is survived by his wife Lorine Warrick Irwin (m. 1994), by two daughters, Esther Nielsen and Nancy Haaf, two sons, Paul Irwin and Alan Irwin, three sisters, a brother, and a large number of grandchildren, great grandchildren, nephews, nieces, and other relatives and friends.
Irwin's greatest legacy is perhaps his photographs of every astronomer he could find at meetings for many years. These were donated to the Center for the History of Physics of the American Institute of Physics (reported in BAAS 22, 1231 ; available online here 1). Another legacy is asteroid 3959, Irwin, discovered at Indiana University. His enthusiasm for astronomy and life will surely be missed by all who knew him.