NATIONAL RADIO ASTRONOMY OBSERVATORY ARCHIVES
Finding Aid to the Papers of Marshall H. Cohen, 1957-2002
See also the Papers of Woodruff T. Sullivan III, which include a 40 minute oral interview with Cohen conducted in 1978.
Location of collection: National Radio Astronomy Observatory, Archives, 520 Edgemont Rd., Charlottesville, VA. Phone: 1-434-296-0203, email: archivist at nrao.edu.
Title and dates of the collection: Papers of Marshall H. Cohen, 1957-2002
Size of the collection: 4 linear feet
Papers/Records created by: Cohen, Marshall H. (Marshall Harris) (1926- )
Short description of collection: The Archives at The National Radio Astronomy Observatory is the repository for Marshall H. Cohen's papers on Very Long Baseline Interferometry (VLBI) and VLBI in the United States, as well as his materials related to the history and early development of the Very Long Baseline Array (VLBA). Other materials related to his career and activities are held by the California Institute of Technology Archives. Two different oral history interviews are held by the California Institute of Technology Archives and by the American Institute of Physics, Center for the History of Physics.
Biography: Marshall H. Cohen was born in Manchester, N.H. on 5 July 1926. As part of the Army Specialized Training Program in World War II, he studied Electrical Engineering at Lehigh University, Virginia Polytechnic Institute, and Ohio State University. After the war he completed the Electrical Engineering degree at OSU and stayed to obtain a PhD in Physics. He moved to Cornell University in 1954 to work on its solar radio astronomy program, and studied the polarization of solar bursts. In 1958 he became involved with the Arecibo project. At Arecibo he studied compact radio sources, and the solar wind, by measuring interplanetary scintillations.
In 1966 he moved to University of California San Diego and two years later to California Institute of Technology. In 1965 he with others started the Very Long Baseline Interferometry program in the US. VLBI quickly verified that compact radio sources were tiny, and a few years later found superluminal motion in the jets in active galactic nuclei. This motion was a major factor in the development of the relativistic beam theory of radio jets. Starting in 1971, in collaboration with Jet Propulsion Laboratory, he developed a VLBI processing laboratory at Caltech, which ultimately grew to have 16-station capability, and for a number of years was a world center for VLBI processing and analysis.
In 1989, spurred by the development of the Keck telescope on Mauna Kea, Cohen with postdocs and students built a polarimeter for the 5-meter Hale telescope and then an improved version for the 10-meter Keck telescope. He used these instruments to study active galactic nuclei and magnetic white dwarfs. He was an early proponent of the Very Long Baseline Array, and since 1994 he has been a collaborator in the 15GHz VLBA survey of motions in AGN; this program has now become the MOJAVE (Monitoring Of Jets in Active Galactic Nuclei with VLBA Experiments) survey. He has become interested in the history of radio astronomy, and has written two articles on the Owens Valley Radio Observatory, and one on the Arecibo Observatory.
[Biographical note written by Marshall H. Cohen.]
Accession history: Marshall H. Cohen donated the papers to National Radio Astronomy Observatory Archives in early 2009.
Access to collection: No restrictions. The Archives are open part-time; contact the Archivist for appointment.
Publication rights: Copyright has been assigned to The National Radio Astronomy Observatory. All requests for permission to publish or quote from manuscripts must be submitted in writing to the Archivist.
Preferred citation: [Identification of item, box, and file], Papers of Marhsall H. Cohen, 1957-2002. Archives, National Radio Astronomy Observatory / Associated Universities, Inc.
Processing notes: Initial inventory of this collection was done in April 2009 by Ellen N. Bouton. Final arrangement, description, indexing, foldering and boxing of this material by Evelyn Braintwain was begun in November 2009 and was completed in January 2009. During the processing, photocopies were made to replace thermofax sheets and newspaper clippings, fasteners were removed, and materials were removed from binders of various types. Duplicates were discarded. The finding aid was created by Bouton with assistance from Marshall H. Cohen and Kenneth I. Kellermann.