Radio Astronomy Summer School – 2008 Introduction – Early ...
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Radio Astronomy Summer School – 2008 Introduction – Early History of Radio Astronomy Tatsuhiko Hasegawa (ASIAA) 1. Radio astronomy was interferometry from the beginning. 2. Closely related to developments in engineering and society. 3. We need to reduce radio noise and to protect radio frequencies.
Transcript of Radio Astronomy Summer School – 2008 Introduction – Early ...
Radio Astronomy Summer School – 2008
Introduction – Early History of Radio Astronomy
Tatsuhiko Hasegawa (ASIAA)
1. Radio astronomy was interferometry from the beginning.2. Closely related to developments in engineering and society. 3. We need to reduce radio noise and to protect radio frequencies.
1870 Maxwell – Theory of Electromagnetic Wave.1889 Hertz – Laboratory Generation and Detection of Radio Electromagnetic Wave.
Many scientists attempted to detect Solar radio emission in m-cm bands – all failed.1901 Planck – Theory of Thermal Blackbody Radiation => Solar thermal radiation will be weak in m-cm band.
Marconi – First long-distance radio communication (across Atlantic ocean). 1902 Heaviside and Kennelly – Earth ionosphere reflects radio waves. Turned out only freq < 20 M Hz.1920-30 Commercial radio telephone service.1933 Jansky discovers cosmic radio wave from Galactic center at 20.5 M Hz.1940 Reber builds a radio telescope and maps cosmic radio emission (from Galactic plane) at 162 M Hz.1941 – 45 Hey, Southworth, Reber (separately) observed Solar radio emission. Radar technology advanced.1945 – 1950 Pawsey (Australia), Ryle (UK) developed interferometry technique. Ryle & Vonberg (Cambridge UK) built a 2-element interferometer and detected Solar flares and Cas A. Bolton & Stanley (Au) used 'Sea interferometry'. 10 compact radio sources were discovered by 1948. Ryle, Smith, Elsmore made first catalog of point radio sources (1C catalog, 1949). Antenna movements and use of Earth rotation. Many dipole antennas to form an interferometer (Mills Au). Many small dishes in cross-pattern (Christiansen Au)1951 First detection of the 21cm line of H I. Ewen & Percell (US). Muller & Oort (D). Pawsey (Au).1955 26m (Dutch). 1956 18m (Harvard). 1957 76m (UK). 1958 27m x 2 (Caltech). 26m (US Navy). 1959 26m (Michigan). 26m (NRAO). 22m (USSR)1960 – 63 Discoveries of radio galaxies.1961 Parks 64m (Au). 25m x 2 (Melbourne, Au). 1962 90m (NRAO). 1963 300m (Arecibo, US). 1963 18m x 3 (Ryle 1-mile UK). 1964 36m (Mark II, UK). 36m (Haystack, US). 1965 42m (GB). 46m (Ca).1965 3K cosmic microwave background radiation. 1967 Discovery of pulsars. 1975 Nobel prize : Martin Ryle & Antony Hewish for contributions to radio astronomy.1978 Nobel prize : Penzias & Wilson for the discovery of cosmic background radiation.
Karl Jansky and his rotating antenna in New Jersey (1928). Courtesy of NRAO/AUI. Jansky, working at Bell Telephone Laboratory, investigated the origin of static noise for radio telephone service.
Grote Reber's telescope in his backyard in Illinois (1938). Reber was a radio engineer. Courtesy of NRAO.
Arno Penzias and Robert Woodrow Wilson (1965) at Bell Laboratory built this radiometer intended for satellite communication and radio astronomy experiments. They encountered an excess antenna temperature of 3.5 K. They could not explain the excess. This led to the discovery of the cosmic microwave background radiation. Courtesy NASA. (http://grin.hq.nasa.gv/ABSTRACTS/GPN-2003-00013.html)
NRAO 25.5m #1 (1958) at Green Bank
Green Bank 90m telescope (1962) before and after the collapse on Nov 15, 1988.
Jodrell Bank Mark I 75m (1957)
First day at Jodrell Bank (1945 Dec)
Parabolic reflecting wires (65 m long) at Jodrell Bank (1947)
Early Activities in Radio Astronomy in the United Kingdom – Courtesy Jodrell Bank Observatory and University of Manchester
Jocelyn Burnell and the 4.5 acre (135 m x 135 m ) array (U of Cambridge) that was used in the discovery of pulsars (1967). Courtesy University of Manchester. ( www.jb.man.ac.uk/distance/life/seti/ ) The facility was intended for Solar radio monitoring. The supervisor was Dr. Hewish.
Eight Yagi-antennas (1951)
Two Yagi-antennas (1947)Cygnus-A detection chart by 'sea interferometry' (1948).
A reflector using a hole in the ground (1953)
Early activities in radio astronomy in Australia at WW II radar station. Courtesy ATNF and CSIRO.
Parkes 64m and 18m (1963)
Compact Array at Narrabi (1988)
Modern Radio Telescopes in Australia
Courtesy ATNF / CSIRO
HI 21cm line was detected and mapped with this 7.5 m telescope (originally a German military radar dish) in Kootwijk, Holland (1951-1956). Prof. Jan Oort was eager to exploit the radio technique.
Wsterbork 25m x 12 (E-W) (in 1970)
Early Activities in Radio Astronomy in The Netherlands
Courtesy ASTRON Westerbork Observatory
Dwingeloo 25m (1956)
