The Bruce Medalists


  Photo 2014, courtesy Dr. Kellermann
Kenneth Irwin Kellermann
1 July 1937 2014 Bruce Medalist

“Ken” Kellermann was born in New York and earned his S.B. in physics at the Massachusetts Institute of Technology in 1959 and his Ph.D. in physics and astronomy at the California Institute of Technology in 1963. He switched from physics to radio astronomy after John Bolton conscripted him as a graduate student assistant. The Owens Valley Radio Observatory was still being built, and Kellermann was one of the first to use its two-element interferometer, completing his Ph.D. under Gordon Stanley with measurements of spectra of both galactic and extragalactic radio sources. He spent part of his graduate studies visiting Martin Ryle’s group at the University of Cambridge. After postdoctoral research with Bolton at the CSIRO Division of Radiophysics, where he observed thermal emission from planets with the relatively new Parkes telescope, he joined the National Radio Astronomy Observatory in 1965. He has been at NRAO ever since, with a few leaves at Leiden, Sydney, Caltech, and Germany, where in 1978 and 1979 he was a Director at the Max Planck Institute for Radio Astronomy, and he has held a concurrent appointment as research professor of astronomy at the University of Virginia. He has served as NRAO’s Acting Assistant Director for Green Bank Operations, as Chief Scientist, and as head of its New Initiatives Office.

Starting in the late 1960s, Kellermann, Barry Clark, and Marshall Cohen became some of the early leaders in the development of Very Long Baseline Interferometry. Soon they were achieving one milliarcsecond resolution, far surpassing optical telescopes, and making maps of galactic and extragalactic radio sources, using antennas in Green Bank together with others in California, Massachusetts, Puerto Rico, and then Sweden, Australia, Germany, and Russia. It was difficult to arrange time and collaboration with many different telescopes, each with its own schedule of observations, so in 1974 a group was organized to design a dedicated array of identical telescopes spread over a large distance. Kellermann led the effort, which took nearly two decades and resulted in the 1993 dedication of the Very Long Baseline Array, with ten 25-m telescopes spread from Hawaii to the U.S. Virgin Islands. He has also been a strong advocate for using radio telescopes in space along with terrestrial ones to achieve even greater baselines and thus higher angular resolution. This has been achieved with Japanese and Russian satellites, the latter leading to observations of active galactic nuclei with unprecedented angular resolution. He was involved from the start in the international project to develop the Square Kilometre Array.

Kellermann’s research, conducted in collaboration with many colleagues, has included gradually increasing the limits of sensitivity of radio telescopes to sources six orders of magnitude weaker than when he started in the field, and making detailed studies of extremely weak sources, often with very high resolution. He shared in the discovery of apparent superluminal motion, and he published the first paper in a refereed journal reporting on a radio search for extraterrestrial intelligence. He has been very active in national and international science policy, serving on a number of committees and panels. He has also contributed to the history of radio astronomy, editing books, writing articles, and promoting the development of the National Radio Astronomy Observatory Archives. He led in the successful efforts to obtain the papers of Grote Reber and other pioneers for these archives.

Personal web page
At the National Radio Astronomy Observatory.

Other awards
American Astronomical Society, Helen B. Warner Prize, 1971.
American Academy of Arts and Sciences, Rumford Prize, 1971 [shared].
National Academy of Sciences, Benjamin Apthorp Gould Prize, 1973.

Biographical materials
NRAO, with finding aid to his papers

National Radio Astronomy Observatory (several)
American Institute of Physics (two)

Named after him
Minor Planet #152985 Kenkellermann

More references

The Bruce Medalists

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