Finding Aid to the Papers of Alan H. Bridle, 1959-2023
Short description of collection: The collection includes material from Bridle’s student years in Cambridge and at the Dominion Radio Astrophysical Observatory (DRAO), from his work while on the faculty of Queen’s University, and from his tenure on the National Radio Aastronomy Observatory (NRAO) scientific staff, including both his research and his observatory service. Also included are materials on the Canadian Long Baseline Array (CLBA) and the potential collaboration of the CLBA with the NRAO's Very Long Baseline Array (VLBA).
Alan Henry Bridle was born in Harrow, Middlesex, England in 1942, He attended Quainton Hall School from 1947 to 1953, then University College School from 1953 to 1959. He began undergraduate studies at Trinity College, Cambridge in 1960 and earned his B.A. in Theoretical Physics from the University of Cambridge in 1963. He then joined the Mullard Radio Astronomy Observatory as a Ph.D. student and used wavelength-scaled dipole arrays to study the galactic spectrum at 13.15, 17.5 and 81.5 MHz and to estimate the intensity of the nonthermal extragalactic monopole, under the direction of Martin Ryle and John Baldwin. In 1965 he went to the Dominion Radio Astrophysical Observatory (DRAO) near Penticton, Canada as a visiting student to use its 10-MHz ‘T’ array to study discrete source spectra under the direction of Carman Costain and John Galt. He returned to Cambridge in 1966 and obtained his Ph.D. in 1967 with a dissertation on “The Spectra of Galactic and Extragalactic Radio Sources”. He held a U.K. Science Research Council post-doctoral fellowship at the Mullard Observatory before joining the faculty of the Department of Physics at Queen's University in Kingston, Ontario, Canada in September 1967.
At Queen’s University, he continued work with DRAO staff on the spectra and flux-density scale calibration of discrete sources at decameter wavelengths, and on using absorption in source spectra at 10 MHz to study the distribution of interstellar electron gas. With Paul Feldman and Carman Costain, he identified sources with steep decametric spectra with X-ray-emitting Abell clusters. He also studied source variability at centimeter wavelengths using the 46-meter telescope at the Algonquin Radio Observatory (ARO), and, with Michael Kesteven, studied 21-cm line absorption of discrete sources using the NRAO 300-ft telescope at Green Bank. Again with Feldman, he used the ARO telescope in a “SETI” search of nearby stars at the 22.25-GHz water vapor line. He worked with Queen's University faculty members in Biology, Geology, and Chemical Engineering to develop honors-level undergraduate courses addressing the origin of life, the origin and evolution of planetary environments, and the long-term energy and resource impacts of technological civilization. While at Queen's University he supervised the M.Sc. Thesis work of D. Glenn MacDonell, Ronald E. Goodson, John Palimaka, and Bert Guindon, and the Ph.D. Thesis work of Bert Guindon.
While a Visiting Scientist in Green Bank in 1970 he worked with Mike Davis, Ed Fomalont and James Lequeux on the “BDFL” catalog of flux densities and structures of a complete sample of sources brighter than 2 Jy at 1.4 GHz using the NRAO 300-ft and the Caltech Interferometer. He later worked with Kesteven and George Brandie to monitor 365 sources for variability at 2.7 GHz with the 300-ft telescope and with Fomalont, Brandie, and John Palimaka to determine the orientations of radio sources relative to elliptical galaxies using the Green Bank Interferometer. With Fomalont, George Miley and Edwin Valentijn, he used the Westerbork Synthesis Radio Telescope at 610 and 1415 MHz to image steep-spectrum emission detected at the DRAO from the cluster Abell 2256. With Davis, Fomalont, Debra Meloy (Elmegreen), Richard Strom and Tony Willis he mapped extended emission from NGC315 at 430, 1410 and 2380 MHz at Arecibo, showing it to be a single giant radio galaxy.
As the VLA came online, he used it to make sensitive images of kiloparsec-scale jets in active galaxies, including the giant sources NGC315 and NGC6251. As a Visiting Scientist in Socorro from 1980 to 1982 he began to explore the systematics of AGN jet collimation and polarization. He also wrote the first “AIPS Cookbook” and served on the Planning Committee for the proposed Canadian Long Baseline Array (CLBA). After joining the NRAO staff in Charlottesville in January1983 his research focused on very-high-sensitivity multi-frequency VLA imaging and polarimetry, using full syntheses in multiple VLA configurations to study the changes in collimation, magnetic field configuration, and spectral index both along and across AGN jets. In 1984, with Rick Perley, he reviewed “Extragalactic Radio Jets” for the Annual Reviews of Astronomy and Astrophysics. He lectured on “VLA Observing Strategies” in the NRAO Synthesis Imaging Summer Schools from 1982 to 1995, wrote the “VLAPLAN” observation planner, and edited the Summer School proceedings with Rick Perley and Frederic Schwab. He edited the NRAO Array Telescope Computing Plan in1985 and, with Tim Bastian, the VLA Development Plan in 1987. With David Hough, Jack Burns, Colin Lonsdale and Robert Laing he used the VLA to search for counterjets in 3CR quasars. He then worked with Laing to model the systematic intensity and polarization asymmetries of AGN jets and their counterjets as manifestations of relativistic aberration, and ultimately to infer the jet velocity fields and estimate their mass fluxes. He worked with Laing and others on correlations of other radio properties with source asymmetries, and on using VLA polarimetry at high resolution to infer the structure of the magnetoionic media around radio-galaxy lobes. He also co-supervised the Ph.D. studies of Stefi A. Baum and Mark R. Swain at the VLA. He worked with the NRAO’s Computing Division on a series of AIPS Site Surveys, on observatory-wide Y2K readiness, and on the early development of tools for NRAO-wide videoconferencing. From 1997 to 2005 he worked with University of Virginia staff and contractors on planning and building the NRAO's Edgemont Road Addition. In 2007, with Gareth Hunt and Jim Condon, he co-edited the NRAO's 50th Anniversary Symposium Proceedings “Frontiers of Astrophysics”. After he retired from the NRAO in October 2008, he continued work with Laing on modeling asymmetries in radio-galaxy jets. In 2011 he and Marshall Cohen co-wrote a chapter on radio studies of jets for the book “Relativistic Jets from Active Galactic Nuclei” edited by Marcus Boettcher, Dan Harris and Henric Krawczynski.
He was a Charter Member of the Canadian Astronomical Society in 1971, a Board Member of the Society from 1981 to 1984, and a Member of the American Astronomical Society and of the International Astronomical Union.
[Biographical note written by Alan H. Bridle.]
Publication rights: Copyright has been assigned to the NRAO/AUI Archives. All requests for permission to publish or quote from manuscripts must be submitted in writing to the Archivist. Note that copyright for all published journal articles remains with the journal publisher.
Preferred citation: National Radio Astronomy Observatory/Associated Universities, Inc. Archives, Papers of Alan H. Bridle, <series/unit/subunit/box #>. After the initial citation, abbreviations may be used: NRAO/AUI Archives, Bridle Papers, <series/unit/subunit/box #>.
Processing notes: Arrangement, description, indexing, foldering and boxing of material donated in 2017 was done in January 2019; material donated in 2023 was processed in 2023. For both sets of donated materials, Bridle's folder titles and arrangement scheme were retained. Bridle had digitized the bulk of the 2023 materials prior to donation. During the processing of paper items, fasteners were removed, and materials were removed from binders of various types. Duplicates were discarded.
Cambridge University Series: Bridle was an undergraduate, graduate student, then post-doctoral fellow at Cambridge University from September 1960-August 1967. This series includes Bridle's notes to self on various topics in physics, also used for teaching undergraduates in college tutorial ("supervision") sessions during 1963-1967; notes taken during graduate lectures given by Martin Ryle, Tony Hewish, Peter Scheuer (all of Cavendish Laboratory), Dennis Sciama (Dept of Applied Mathematics and Theoretical Physics - DAMTP) and Hermann Bondi (visiting DAMTP); photographs taken at the old Rifle Range (3C) Observatory in 1964-1965 while Bridle was measuring the radio background spectrum for his Ph.D. thesis; Bridle's notes on cosmological models and the integrated extragalactic radio emission (quantity estimated from radio background spectrum data in Ph.D. thesis); log book of Bridle's notes on the dipole array for his thesis work; copies of the original 2C, 3C, and 4C catalogues [not available online]; correspondence; and miscellaneous other materials related to Bridle's time at Cambridge. Size: 0.25 linear feet, 47 digital files. Click here for an item listing.
Dominion Radio Astrophysical Observatory (DRAO) Series: From September 1965 to August 1966 Bridle was a visiting student at the Dominion Radio Astrophysical Observatory (DRAO) near Penticton, Canada, using its 10-MHz 'T' array to study discrete source spectra under the direction of Carman Costain and John Galt. This series includes notes, papers, photographs, and other material on DRAO and Bridle's work while there, including a handbook on how to use the 10-MHz 'T' array written by Bridle and summer student Rick Choquette. Size: 0.25 linear feet, 44 digital files. Click here here for an item listing and links to digital files.
Queen's University Series: Bridle was on the faculty at Queen's University Department of Physics, in Kingston, Ontario, Canada, September 1967-January 1983. General materials include course materials, lecture notes by Bridle and others, publications, photographs, materials recognizing Bridle on the 30th anniversary of astronomical formatting standards, and miscellaneous materials, both digital and paper-only, dated 1967-2019. Size: 0.50 linear feet, 39 digital files. Click here for an item listing and links to digital files.
Canadian Long Baseline Array (CLBA) Series: An initial propopsal for a Canadian Long Baseline Array was submitted to a committee of the Canadian Astronomical Society (CAS) in 1978, and shortly thereafter the CAS adopted an expanded version of the proposal and recommended that the CLBA be given the highest priority for a new Canadian astronomical instrument. The CLBA Planning Committee, of which Bridle was a member, was formed in 1980, and produced a report in September 1982 summarizing the proposed design, construction, and operation of the array. On 31 May 1983, The National Research Council of Canada formally approved a new national facility, the Canadian Long Baseline Array, made up of eight radio telescopes spaces across southern Canada, with a ninth antenna, primarily for geophysics, in the north. This series includes correspondence, reports, and other materials dated 1979-1986. Bridle's folder titles and arrangement scheme have been retained. Size: 1.0 linear feet. Click here for a listing of folders.
National Radio Astronomy Observatory (NRAO) Series: This series includes materials dated 1980-2022 on various NRAO activities and projects with which Bridle was involved, including Y2K preparation at NRAO, introduction of video conferencing, the 300 Foot Telescope collapse, Synthesis Imaging Summer Schools, computing and information science, the Edgemont Road building addition, Large Proposals Committee, and general correspondence and research materials. Size: 0.5 linear feet, 107 digital files. Click here for an item listing and links to digital files. For additional materials on Bridle's work as staff advisor for the 2002-2005 construction of Charlottesville's Edgemont Rd. building addition, see the Records of NRAO, Charlottesville Operations.
Bridle Publications Series: Material related to Bridle's publications and scientific talks (1967-2021) including copies of publications as well as related correspondence and other documents. Size: 1.5 linear feet, 201 digital files. Click here for an item listing and links to digital files.here for an item listing and links to digital files.