Grote Reber and his Radio Telescope
Grote Reber was born in Chicago on December 22, 1911 (d.12/20/2002). He was a ham radio operator, studied radio engineering, and worked for various radio manufacturers in Chicago from 1933 to 1947.
He learned about Karl Jansky's discovery (1932) of radio waves from the Galaxy (i.e., the Milky Way), and wanted to follow up this discovery and learn more about cosmic radio waves. Were the waves coming only from the Milky Way, or from other celestial objects? What process produces the radio waves?
(Click on any picture for a larger version)
The picture at left is copied from "A Play Entitled the Beginning of Radio Astronomy", by Grote Reber, in The Journal of the Royal Astronomical Society of Canada, Vol.82, No.3, June 1988, page 93. This article is a delightful reminiscence about the author's early work in radio astronomy and that of Karl Jansky.
In the 1930s Reber applied for jobs with Karl Jansky at Bell Labs and with astronomical observatories to study cosmic radio waves, but none of them were hiring at the time, since it was in the middle of the great depression. Reber decided to study radio astronomy on his own.
The telescope was constructed by Grote Reber in 1937 in his back yard in Wheaton, Illinois (a suburb of Chicago). He built the telescope at his own expense while working full time for a radio company in Chicago. This shows the telescope as it was in Wheaton, Ill.
The mirror, made of sheet metal 31.4 feet in diameter, focuses radio waves to a point 20 feet above the dish. The cylinder contains the radio receiver which amplifies the faint cosmic signals by a factor of many million, making them strong enough to be recorded on a chart. The wooden tower at the left is used for access to the receiver.
Reber built a parabolic dish reflector because this shape focuses waves to the
same focus for all wavelengths. This principle had been used for a long time
by astronomers for design of optical telescopes, to avoid chromatic aberration.
Reber knew that it would be important to observe a wide range of wavelengths
of radiation from the sky in order to understand how the radiation was being
produced. A parabolic reflector is usable over a wide wavelength range.
Reber spent long hours every night scanning the skies with his telescope. He had to do the work at night because there was too much interference from the sparks in automobile engines during the daytime.
The first receiver designed for 3300 MHz failed to detect signals from outer space. So did the second, at 900 MHz. Finally a third receiver at 160 MHz (1.9 meters wavelength) was successful in detecting radio emission from the Milky Way, in 1938, confirming Jansky's discovery.
Chart recordings from Reber's telescope made in 1943. The spikes or "fuzz" are due to interference from automobile engine sparks. The broader peaks are due to the Milky Way and the Sun. This chart recording is a copy of part of Figure 5 from "Cosmic Static", by Grote Reber, in the Astrophysical Journal, Vol.100, page 279, 1944.
Reber surveyed the radio radiation from the sky and presented the data as contour maps showing that the brightest areas correspond to the Milky Way. The brightest part is toward the center of the Milky Way galaxy in the south. Other bright radio sources, such as the ones in Cygnus and Cassiopeia, were recognized for the first time.
The contour diagram at left is copied from "Galactic Radio Waves" by G.Reber, which was published in Sky and Telescope, Vol.8, No.6, April, 1949. The diagrams are plotted in galactic coordinates in which the galactic equator runs horizontally. Most of the radio radiation is in or near the galactic equator. The vertical axes are galactic latitude in degrees. The horizontal axes are galactic longitude, in which the direction toward the center of the galaxy has longitude=0.
In the years from 1938 to 1943, Reber made the first surveys of radio waves from the sky and published his results both in engineering and astronomy journals. His accomplishments insured that radio astronomy became a major field of research following World War II. Research groups in many countries began building bigger and better antennas and receivers to follow up on Reber's discoveries.
Grote Reber donated his telescope to NRAO at Green Bank, WV, and supervised its assembly there in the early 1960s. It remains there as a historical monument. It was put on a turntable allowing it to point in any direction. This picture was taken in the late 1970's after the telescope was painted red, white, and blue for the US bicentennial.
What produces the radio emission? The process that produces the emission can be deduced from the spectrum, i.e., the graph of how power changes with frequency. Reber found that the radio power was weaker at higher frequencies, contrary to what was predicted by the theory of thermal radiation. This theory applies to the light from stars, or any hot object such as molten iron or stove burners, and predicts that the radio emission increases at higher frequencies. But Reber found just the opposite relation for the Milky Way. Some other, "non-thermal", process had to be at work.
It was not until the 1950s that a Russian physicist, V.L.Ginzburg, worked out the theory of synchrotron radiation, which explains the observed radio spectrum. Synchrotron radiation results from electrons moving at speeds close to the speed of light in magnetic fields. Our galaxy is full of high speed charged particles, including electrons, known as "cosmic rays". We now believe that these particles were blasted into interstellar space as a result of supernova explosions. This is the origin of most of the radio radiation from the Milky Way that Jansky and Reber measured.
Later work by Reber
In the 1950s, Reber sought a field that seemed neglected by most other researchers and turned his attention to cosmic radio waves at very low frequencies (1-2 MHz, or wavelength 150-300 meters). Waves of these frequencies cannot penetrate the Earth's ionosphere except in certain parts of the Earth at times of low solar activity. One such place is Tasmania, where Reber lived for many years. He died in Tasmania on December 20, 2002.
An obituary for Reber was written by Ken Kellermann and published in Nature for February 2003 (vol.421, page 596).
Publications by Grote Reber
Note: Reber's papers on "Cosmic Static", 1940-1948, were reprinted in "Classics in Radio Astronomy", by W.T.Sullivan, Cambridge Univ.Press. 1982
1938: "UHF receivers", by G.Reber and E.H.Conklin, Radio, no.225, p.112. (Jan.1938)
1938: "Electric resonance chambers", Communications, 18, p.5, December 1938.
1939: "Electromagnetic horns", Communications, 19, p.13, Feb.1939.
1939: Radio, no.235, p.17, Jan 1939; also front cover, no.236, Feb.1939.
1940: "Cosmic Static", Proc.IRE, 28, 68.
1940: "Cosmic Static", Astrophysical Journal, 91, p.621.
1942: "Cosmic Static", Proc.IRE, 30, 367.
1944: "Filter networks for uhf amplifiers", Electronic Indus., 3, p.86.
1944: "Reflector Efficiency", Electronics Industry, vol.3 (or 17?), 89-101.
1944: "Cosmic Static", Astrophysical Journal, 100, 279.
1946: "Solar Radiation at 480 Mc.sec.", Nature, 158, 945.
1947: "Radio-frequency investigations of astronomical interest", by G.Reber and J.L.Greenstein, The Observatory, vol.67, no.836, p.15, Feb. 1947.
1947: "Antenna Focal Devices for Parabolic Mirrors", Proc.IRE, 35, 731.
1948: "Solar Intensity at 480 Mc", Proc. IRE, 36, no.1, p.88.
1948: "Cosmic Radio Noise", Radio-Electronic Engineering, July 1948.
1948: "Cosmic Static", Proc.IRE, 36, 1215, 1948.
1949: "Galactic Radio Waves", Sky and Telescope, vol.8, p.139.
1949: "Radio astronomy", Scientific American, vol.181, p.34, Sept.1949.
1950: "Galactic Radio Waves", ASP Leaflet no.259, 1950.
1954: "Spread F over Hawaii", Jour.Geophys.Res., 59, p.257.
1954: "Spread F over Washington", Jour.Geophys.Res., 59, p.445.
1955: "Radio Astronomy in Hawaii", Nature, 175, 78.
1955: "Fine structure of solar radio transients", Nature, 175, 132.
1956: "Cosmic radio-frequency radiation near one megacycle", by G.Reber and G.R.Ellis, J.Geophys.Res., 61, 1.
1956: "World-wide spread F", Jour.Geophys.Res., 61, p.157.
1957: Paper in CSIRO Radiophysics Lab. Symposium on Radio Astronomy, Sydney, Sept.1956, pub. by Melbourne, 1957.
1957: "Atmospheric Pressure atop Haleakala", Australian Meterological Mag. no.18, p.50, Sept.1957.
1958: "Between the atmospherics", Jour.Geophys.Res., 63, p.109.
1958: "Early Radio Astronomy at Wheaton, Illinois", Proc.IRE, 46, p.15. Jan 1958.
1958: "Solar activity and spread F", Jour.Geophys.Res., 63, p.869.
1959: "Radio interferometry at three kilometers altitude above the Pacific Ocean", J.Geophys.Res., 64, 287.
1959: "Suppressed sidelobe antenna of 32 elements", Inst.Radio Engrs.Trans.Ants.and Prop., vol.AP-7, p.71.
1960: "Reversed bean vines", Castanea, 25, p.122.
1964: "Reversed bean vines", Jour.of Genetics, 59, p.37.
1964: "Hectometer cosmic static", IEEE.Trans.Antennas.Propagation, AP-12, 923.
1964: IEEE Transactions on Military Electronics, July-October, p.258.
1965: "Ground-Based Astronomy: The NAS 10-year program", Science, 152, p.150.
1966: "Cosmic ray astronomy", J.Franklin Inst., 281, no.1, p.1.
1967: "Atmospheric pressure oscillations in Tasmania", Australian Meterological Magazine, 15, p.156, Sept.1967.
1967: "Unusual variation in Phaseolus Vulgaris", Australian Jour.of Exptl.Agriculture, v.7, p.377.
1968: "Cosmic static at 144 meters wavelength", J.Franklin Inst., 285, no.1, p.1.
1970: "Cosmic ray muons from low galactic latitude", by Chu, Kim, and Reber, Publications of the Astronomical Society of the Pacific, 82, 339.
1977: "Endless, boundless, stable universe", U.Tasmania, occasional Paper number 9 (1977).
1982: "A timeless, boundless, equilibrium universe", Proc.Astron.Soc.Aust., v.4, no.4, p.482.
1982: "Big bang creationism", Letter to the Editor, Physics Today, 35, p.108, Nov.1982, p.108.
1984: "Early Years of Radio Astronomy", ed. W.T.Sullivan, Cambridge Univ.Press, 1984.
1984: "Radio Astronomy between Jansky and Reber", in Serendipitous Discoveries in Radio Astronomy, ed.Kellermann and Sheets, Proc.NRAO Workshop no.7, p.71. (Green Bank, WV, May 1983). Pub.by NRAO, 1984.
1986: "Intergalactic plasma", IEEE Trans.Plasma Sci., vol.PS-14, no.6, p.678.
1987: "Low-frequency radioastronomical observations during the Spacelab 2 plasma depletion experiment", by Ellis, Klekociuk, Woods, Reber, Goldstone, Burns, Dyson, Essex, and Mendillo. Aust.Phys., 24, no.3, 56.
1987: "Spacelab-2 Plasma Depletion Experiments for Ionospheric and Radio Astronomical Studies", by M.Mendillo, J.Baumgardner, D.P.Allen, J.Foster, J.Holt, G.R.A.Ellis, A.Klekociuk, and G.Reber., Science, 238, 1260.
1988: "A play entitled the beginning of radio astronomy", J.Roy.Astron.Soc.Can., 82, no.3, p.93.
1988: "Radioastronomy through an artificial ionospheric window: Spacelab-2 observations", by Ellis, Klekociuk, Woods, Reber, Goldstone, Burns, Dyson, Essex, and Mendillo. Adv.Space Res., v.8, no.1, p.63.
1989: "Cosmic matter and the nonexpanding universe", P.Marmet, G.Reber. IEEE Trans.Plasma Sci., 17, no.2, 264.
1990: "Hectometer and kilometer wavelength radio astronomy", Proceedings of workshop on Low Frequency Astrophysics from space, ed. by Kassim and Weiler. Springer.
Related Publications on Low-Frequency Astronomy by some of Reber's Collaborators.
1965: G.R.A.Ellis, Monthly Notices of the Royal Astronomical Society, 130, 429.
1971: R.R.Weber, J.K.Alexander, R.G.Stone, Radio Science, 6, 1085.
1975: J.K.Alexander, M.L.Kaiser, J.C.Novaco, F.R.Grena, R.R.Weber, Astron.Astrophys., 40, 365.
1978: J.C.Novaco and L.W.Brown, Astrophysical Journal, 221, 114.
1982: G.R.A.Ellis, Australian Journal of Physics, 35, 91.
1987: G.R.A.Ellis and M.Mendillo, Australian Journal of Physics, 40, 707.
Non-expanding universe (referred to by Reber):
1989: H.Reeves, J.Roy.Astr.Soc.Can, 83, 223.
The following biography of Reber appeared in the December 1964 issue of IEEE Transactions on Antennas and Propagation, Vol.AP-12, No.7, page 966.
Grote Reber was born in Chicago, Ill., on December 22, 1911. He received the B.S. degree from the Illinois Institute of Technology, Chicago, in 1933. In 1962, he received an honorary Doctor of Science degree from The Ohio State University, Columbus.
He worked in an engineering capacity for several radio manufacturers in Chicago from 1933 to 1947. From 1936 on, he pioneered in radio astronomy experiments, first on a part-time and later on a full-time basis. He was Radio Physicist at the National Bureau of Standards from 1947 to 1951. From 1951 to date, Dr. Reber has been associated with the Research Corporation conducting radio astronomy investigations in Hawaii and Tasmania. He is also currently Hororary Research Fellow of the Division of Radio Physics of the Australian Commonwealth Scientific and Industrial Research Organization.
Dr. Reber is a member of the American Astronomical Society. In 1962, he was the American Astronomical Society Russell Lecturer and also the recipient of the Bruce gold medal of the Astronomical Society of the Pacific. In 1963, Dr. Reber received an Elliot Cresson gold medal from the Franklin Institute of Pennsylvania, Philadelphia.
[In 1976 he received the Jansky prize of the National Radio Astronomy Observatory. -ed.]Compiled and edited by F. Ghigo, NRAO-Green Bank, WV. Modified on Monday, 29-Nov-2004 09:53:15 EST