When CCDs revolutionized optical astronomy, Bev Oke was quick to build them into his instruments.

John Beverly Oke
1928— 2004

Bev Oke, professor of astronomy, emeritus, died of heart failure on Tuesday, March 2, at his home in Victoria, British Columbia, just 21 days short of his 76th birthday. He earned his bachelor’s and master’s degrees from the University of Toronto in 1949 and 1950, respectively, his doctorate from Princeton University in 1953, and was a member of the Caltech faculty from 1958 until his retirement in 1992. He was also a staff member of the Hale Observatories (Mount Wilson and Palomar) and served as associate director from 1970 to 1978.

His scientific work covered wide areas of astronomical spectroscopy, from white dwarfs to active galactic nuclei, clusters of galaxies, and supernovae. However, he is perhaps best known for devising and building unique instruments for the 200-inch Hale Telescope at Palomar, and later for the Keck. “He was one of the first really serious and really excellent astronomer-instrumentalists,” says James Gunn (PhD ’66), Higgins Professor of Astronomy at Princeton University Observatory, “and he and the instruments he designed and built were very largely responsible for keeping Palomar and the 200-inch telescope so far ahead of the rest of the world during the ’60s, ’70s, and ’80s.”

The first instrument Oke built after joining the Caltech faculty was a single-channel scanner for the 200-inch that could measure the spectra of stars and galaxies in successive 10-nanometer-wide segments, according to Wallace Sargent, the Bowen Professor of Astronomy, writing in the April 1 issue of Nature. This spectrophotometer was to play an important role in 1963, when Maarten Schmidt, the Moseley Professor of Astronomy, Emeritus, was taking photographic plates of the mysterious “radio star” 3C273 (now known to be a quasar), and realized that spectral lines indicating the presence of hydrogen, normally seen in the green and violet end of the visible spectrum, appeared to have been shifted to the red. Oke observed the star with his photometer and found a spectral line in the invisible infrared region, which confirmed that the light from 3C273 had a very high redshift, and must have been moving away from the earth at one-sixth the speed of light. The discovery caused a sensation at the time.

“For as long as I knew him, he would be either building an innovative instrument or planning the next one,” says Schmidt. And indeed, in 1968, Oke’s multichannel photoelectric spectrometer was ready for use on the 200-inch. Its ability to measure the absolute spectral energy distributions of extremely faint objects benefited many astronomers over the years; Oke himself used it to measure the spectra of stars, Seyfert galaxies, and quasars.

In the late 1970s, he designed and built an innovative double spectrograph that split the light beam to go through two separate spectrographs, one fitted with a charge-coupled device (CCD) optimized for blue light, the other with a CCD optimized for red. This instrument, now with upgraded CCD technology, is still in use at Palomar.

More recently, a low-resolution imaging spectrograph that he designed and built with astronomy professor Judith Cohen for one of the twin 10-meter Keck Telescopes in Hawaii produced many of the telescopes’ early successes, including the discovery and analysis of hundreds of galaxies at very high redshifts.

Despite building instruments and teaching, Oke found time to publish a large number of scientific papers, recounts Sargent. One of his main achievements was his fundamental work in calibrating the magnitude system used by astronomers to measure starlight. This calibration is still the standard in use today.

“He was as much a workaholic as anybody at Caltech, but seemed in the midst of it all to have much more time for students and really enjoyed interacting with students more than anybody else,” says Gunn. “I, for one, benefited enormously from his attention when I was a student, and I was certainly not alone. I had a special relationship with him which began in the ’60s while I was still a graduate student and which continued for many years later, because I was also keenly interested in instrumentation, and passed from apprentice and friend to very close colleague and friend. I think we have lost someone who was vastly important to the field in ways we will probably never properly recognize.” In Nature, Sargent describes him as “a modest, phlegmatic man with a laconic sense of humor. His lectures were clear, matter of fact and unadorned with fanciful speech. He led by example, not by fine words.”

On retiring from Caltech in 1992, Oke returned to his native Canada to continue his research at the Herzberg Institute of Astrophysics in Victoria. At the time of his death, he was working on the design of a spectrograph for the proposed Thirty-Meter Telescope, a joint venture between Caltech, the University of California, the Association of University Research in Astronomy, and its Canadian equivalent. He is survived by his wife, Nancy; sons, Christopher and Kevin; and daughters, Jennifer and Valerie. “His greatest indulgence was his MG sports car, which he delighted to drive along the S6 ‘highway to the stars’ up to Palomar Mountain,” Sargent writes. He was still working on it the day before he died. —BE