RADIO ASTRONOMY TIMELINE
By Winter Sie-Hilland and Kevin Mogk
Image courtesy of NRAO/AUI
MAJOR DISCOVERIES
•
1951 the 21 cm line for neutral Hydrogen is first observed (National Radio
Astronomy Observatory. 2011.)
•
1941 First radio map of the sky by Grote Gerber (MITTON 20057 p289)
•
1942 Stanley Hey finds radios bursts from the sun. (Space Academy.
2014; HEY 1973)
•
1955 Burke and Frankelin discover radio noise coming from Jupiter.
(Space Academy. 2014 )
•
1961-63 Discovery of quasars (Space Academy. 2014 )
•
1964 Discovery of a uniform e-m radiation that permeates in all
directions of the universe, became know as the Cosmic background
radiation, or cosmic microwave background at a temperature of 2.73 K
(MITTON 2007 p74-5)
•
1967 Jocelyn Bell and Tony Hewish discover the first pulsars. (Space
Academy. 2014 )
•
1992 the space telescope COBE (Cosmic Background Explorer)
discovers temperature variations in the CMB of 1/1,000,000 of a degree,
consistent with the big bang theory (MITTON 2007 p74-5)
JANSKY
• Karl Guthe Jansky was born in Norman Oklahoma, October 22, 1905
(d.Feb.14, 1950)
• Degree in physics from the University of Wisconsin
• Worked for Bell Telephone Laboratories in Holmdel, NJ, beginning in 1928
• New York Times of May 5, 1933.
Photo Credit:
Bell Labs
THE 21 CM LINE
•
In 1944 Desiring to see beyond the dust lanes of the Milky Way, Jan
Oort postulates the idea of an immersion line for hydrogen in the
electro-magnetic spectrum at a wavelength that could piece the
dust of out inner galaxy.
•
In 1945 Hulst, one of Oorts students, predicts that neutral hydrogen
would be visible at the 21 cm line.
•
It is not until 1951 That Harold Ewen and Edward Prucell succeed in
the detection of the 21 cm line with their horn shaped antenna at
Harvard University.
National Radio Astronomy
Observatory 2003 and 2011
REBER AND KRAUS:
SURVEYORS OF STATIC
•
Grote Reber built a radio telescope in his
back yard in 1937
• First systematic survey of radio waves
from the sky
• A range of wavelengths
• 3300 MHz
• 900 MHz
• 160 MHz (1.9m wavelength)
NARO; Reber’s Telescope, now
at Green Bank WV
• Published the first radio sky survey in
the Astrophysical Journal [ApJ 100,
279 (1944)].
• John Kraus, after World War II, started a radio observatory at Ohio
State University and wrote a textbook on radio astronomy, which is still
the "bible" for radio astronomers.
OTHER FORMS BESIDES DISHES
• 1951 H1 Horn
• Ewan and Purcell’s
H1 galactic
emmision detector
• 1.4 GHz,
wavelength of
21cm
• 1962 Echo Horn
Reflector (Bell Labs horn
antenna)
• Penzias and Wilson
discovered cosmic
background
radiation
Horn Antenna — Holmdel, New Jersey.
Horn Antenna, circa 1960.
(Photo Credit: Bell Labs)
DISHES
•
1957 Jodrell Bank Lovell Telescope
• 76 meter steerable antenna
(3rd largest in world now)
•
1962 Arecibo (Upgraded in 1974
and 1996)
• 1000 foot (305 m) diameter
spherical surface
• 8GHz max, wavelength of 3.8
cm
•
1972 Effelsberg
• 100 m dish that has flex
(Homology)
• 86 GHz max
•
NRAO GBT (Pics next slide)
• 100 m aperture
• 290 MHz to 100 GHz
Arecibo: Image courtesy of the NAIC - Arecibo
Observatory, a facility of the NSF
DISH OR
NO DISH
Green Bank 300 ft
telescope: Images
courtesy of NRAO/AUI
At 9:43 p.m. EST on
Tuesday the 15th of
November 1988, the 300Foot telescope in Green
Bank collapsed
INTERFEROMETRY
INTERFEROMETERS
• 1948 Dover Heights Sea
Interferometer, Australia
• 1962 Cambridge
Interferometer
• 178 MHz
• Produced the 4C
Catalog (Ryle and
Neville, (MNRAS 125, 39,
1962))
GBI; Image courtesy of NRAO/AUI
INTERFEROMETERS
• 1963 Ohio State Big Ear,
USA (Kraus design)
• 175ft diameter dish at
1.4 GHz. Wavelength
21 cm (H1)
• 1965 Nancay, France
• 1978 GBI (Green Bank 3Element Interferometer)
• 300 foot and 140 foot
• Offline 2000, due to
funding
VLA
VERY LARGE ARRAY (1980)
Image courtesy of
NRAO/AUI
• 27 individual antennas
arranged in a "Y" pattern
• Each antenna in the array
measures 25 meters (82
feet) in diameter and
weighs about 230 tons
• Four times each year, the VLA
antennas are moved into new
configurations by a
transporter that moves along
dual sets of railroad tracks
• their closest configuration
(about 1 kilometer wide) the
VLA is able to image large
portions of the sky
• largest configuration is about
36 kilometers wide
•
The Very Large Array (VLA) radio telescope is located on the plains of San Agustin,
80 kilometers (50 miles) west of Socorro, New Mexico
•
NRAO (National Radio Astronomy Observatory) operated by Associated
Universities, Inc. under a cooperative agreement with the National Science
Foundation
ARRAYS, THEN V.S. NOW
• Jansky detected three powerful (~10000 Jy) sources
• The expanded Very Large Array can see 1 μJy
• (100000000000 times improvement in resolution from Jansky)
• Part of difference is collecting area. The rest is due to cooled
broadband receivers with HEMT amplifiers for cm wavelength and SIS
mixers for mm λ’s
* For reference, a cell phone on the Moon would produce a signal at
earth of roughly 50,000 Jy
VERY LONG BASELINE ARRAY
The VLBA was dedicated in 1993
•
•
•
10 radio antennas
spread out
Each antenna is 82 feet
(25 meters) in diameter,
weighs 240 tons
data from each of the
ten antennas are
recorded onto
magnetic discs and
shipped to the Array
Operations Center
where they are
combined in pairs in a
correlator, the
specialized
supercomputer at the
heart of an
interferometer
(analogous to the VLA)
Image courtesy of NRAO/AUI and Earth image courtesy of the SeaWiFS
Project NASA/GSFC and ORBIMAGE
Composite image credit: Tae-Hyun, Jung (MPIfR, 2004)
ALTACAMA LARGE
MILLIMETER/SUBMILLIMITER ARRAY
(ALMA ) (2013)
•
•
•
•
A giant array of 12-m antennas (the 12-m
array)
• with baselines up to 16 km
A compact array of 7-m and 12-m antennas
to greatly enhance ALMA's ability to image
extended targets
Located on the Chajnantor plateau at 5000m
altitude
Initially, it will observe at wavelengths in the
range 3 mm to 400 μm (84 to 720 GHz)
*antennas can be moved around, in order to
form arrays with different distributions of baseline
lengths
The design of ALMA is driven by
three key science goals:
1. The ability to detect spectral line
emission from CO or [CII] in a
normal galaxy like the Milky Way
at a redshift of z=3, in less than 24
hours
2. The ability to image the gas
kinematics in protostars and in
protoplanetary disks around
young Sun-like stars in the
nearest molecular clouds (150
pc)
3. The ability to provide precise
high dynamic range images at
an angular resolution of 0.1
arcsec
LONG WAVELENGTH ARRAY
The LWA is an effort to advance astronomy by using inexpensive antenna stations
to build a very large aperture to probe the depths of space at the lowest
frequencies –
between 10 MHz and 88 MHz
LOFAR in Germany will work on the same concept when complete
(www.lofar.org)
2011 construction
complete
This first station is referred
to as LWA1, and consists
of 256, dual-polarization
dipoles (10-88MHz) built
at the VL site next to the
VLA site
Image courtesy of The LWA Consortium
THE FUTURE OF RADIO:
THE SQUARE KILOMETER ARRAY
“The SQUARE KILOMETRE ARRAY is a
global project to design and construct
a next generation international radio
telescope. The SKA will detect
electromagnetic radiation at
wavelengths from meters to
centimetres with a collecting area of
one million square meters (one square
kilometre); 100 times larger than our
most powerful existing radio telescope
array.” http://www.skatelescope.ca/
SKA IS MADE UP OF
ASKAP antennas (MRO)
in Western Australia,
2010.
Credit: WA Department
of Commerce
The Australian
SKA Pathfinder
(ASKAP) telescope
• It is made of 36 identical 12metre wide dish antennas and
will form the basis of a 96-dish
survey telescope to be built in
SKA's first phase
• Equipped with innovative
Phased Array Feed (PAF)
receivers designed and built
by CSIRO
• PAFs provide multi-pixel
images of the sky,
allowing it to survey large
areas of the sky quickly.
SKA IS MADE UP OF
Image is one of 128 tiles of the
Murchison Widefield Array
(MWA) telescope.
Credit: WA Department of
Commerce
Murchison Widefield Array
•
(MWA) is a revolutionary low-frequency telescope with no moving
parts.
•
By computing the received signals with a supercomputer, radio
waves from sections of the sky are isolated making it is possible for
the telescope to be shared between observers studying different
parts of the sky at once
NOBEL
•
1974 the Nobel prize for physics was awarded to Sir Martin Ryle and
Antony Hewish for their pioneering work in radio astronomy.
• Ryle was recognized for his observations and inventions
including the aperature synthesis technique.
• Hewish for his role in discovering pulsars.
•
1978 the novel prize for physics was awarded half to Arno Allan
Penzias & Robert Wilson for their work in the discovery of the cosmic
microwave background. (the other half to Pyotr Kapista for
discoveries in low temperature physics.)
Nobel Prize 2014 A & B
QUESTIONS
•
SKA Video if there is time:
http://www.ska.edu.au/downloads/assets/SKA_HD.mp4
References
ALMA. 2014. General Website. http://www.almaobservatory.org/
BURKE, Bernard; GRAHAM-SMITH, F. 2010. An Introduction to Radio Astronomy. New York: Cambridge
University Press. 444 pp. 3rd ed.
COUPER, Heather and HENBEST, Nigel. 1999, The Firefly Space Encyclopaedia, London; DK Publishing.
303pp.
FREEDMAN, Roger; KAUFMANN III, William. 2005. Universe. New York: W. H. Freeman Company. 693
pp. 7th ed.
HEY, J. S. 1973. An Evolution of Radio Astronomy. New York: Science History Publications. 214 pp.
MITTON, Jacqueline. 2007. Cambridge Illustrated Dictionary of Astronomy. New York: Cambridge University
Press. 397 pp.
National Radio Astronomy Observatory. 2011. “Doc” Ewen and the discovery of Radio emission from
Hydrogen. http://www.nrao.edu/whatisra/hist_ewenpurcell.shtml
National Radio Astronomy Observatory. 2003. Prediction of 21cm Line Radiation.
http://www.nrao.edu/whatisra/hist_oortvandehulst.shtml.
National Radio Astronomy Observatory, History of Radio Telescopes, Paul Vanden Bout
http://apps3.aps.org/aps/meetings/april09/presentations/C6-2-VandenBout.pdf
Nobel Prize. 2014 A. TheNobel prize in Physics 1974.
http://www.nobelprize.org/nobel_prizes/physics/laureates/1974/.
Nobel Prize. 2014 B. TheNobel prize in Physics 1974.
http://www.nobelprize.org/nobel_prizes/physics/laureates/1978/
Space Academy. 2014. The First 50 Years of Radio Astronomy.
http://www.spaceacademy.net.au/museum/RA50.htm
The Long Wavelength Array, http://www.phys.unm.edu/~lwa/index.html
The Square Kilometre Array. 2014 A. The SKA Layout. https://www.skatelescope.org/location/layout/
The Square Kilometre Array. 2014 B. The Project Timeline.
https://www.skatelescope.org/project/projecttimeline/ CSIRO. 2014 A. CSIRO ASKAP Radio Telescope.
http://www.atnf.csiro.au/projects/askap/index.html
CSIRO. 2014 B. CSIRO ASKAP Timeline. http://www.atnf.csiro.au/projects/askap/timeline.html