New Telescope as Big as Earth Itself
UA Steward Observatory radio telescopes are the U.S. part of a global array
of telescopes, a viritual telescope of unequaled power.(GRAPHIC: Courtesy of
New Telescope, Most Powerful Yet
Developed, Is as Big as Earth Itself
Lucy Ziurys, UA
Sheperd Doeleman, MIT
Thomas Krichbaum, MPIfR
Albert Greve, IRAM
Astronomers have created an Earth-sized virtual radio telescope that can detect
features 3,000 times smaller than the Hubble Space Telescope can see.
The virtual device, which was created by linking signals from radio telescopes
on several continents, is the first to operate at shortest-ever (2 millimeter)
The international collaboration involves two telescopes in Arizona – the
Heinrich Hertz Submillimeter Telescope (HHT)on Mount Graham and the Kitt Peak
12-meter Telescope – and telescopes in Spain, Finland, and Chile.
"Both the distance between partner telescopes and the ability to detect shorter
wavelength, higher frequency radio emission gives this telescope its
unprecedented power," said Lucy Ziurys, director of the Arizona Radio
Observatory, part of the University of Arizona's Steward Observatory in Tucson.
Astronomers define telescope power is terms of angular resolution -- the ability
to clearly separate two closely spaced objects in the sky. At its
record-breaking best, the telescope resolved an angle of 50 micro arc seconds,
or about one hundred millionth of a degree of the sky.
"The resolution achieved by this telescope is the equivalent of sitting in New
York and being able to see the dimples on a golf ball in Los Angeles," said
Sheperd Doeleman of the Massachusetts Institute of Technology's Haystack
The Heinrich Hertz
Submillimeter Telescope, operated by Steward Observatory and the
Max-Planck-Institute for Radio Astronomy in Bonn, Germany, on Mount Graham,
Ariz., is part of the virtual telescope (Photo: Lori Stiles)
Ziurys, Doeleman, Thomas Krichbaum of the
Max-Planck-Institute for Radio Astronomy in Bonn, Germany, and Albert Greve of
the Institut de Radioastronomie Millemetrique (IRAM), which operates telescopes
in Granada, Spain, and Grenoble, France, are principal collaborators on the
project. Finland's Metsahovi Radio Observatory, the European Southern
Observatory's Swedish-operated SEST telescope, and the National Radio Astronomy
Observatory are also involved. The National Science Foundation and the
Tucson-based Research Corporation help fund the U.S. effort.
The world's most powerful radio telescope began to materialize late last year,
when Greve, Ziurys, and Doeleman agreed to attempt 2mm-wavelength observations
using Kitt Peak's 12-meter telescope and Mount Graham's HHT as the U.S.
component of the international telescope array.
At that time, we didn't have the capability to do 2mm observations at the HHT,"
Ziurys said. "We could build the devices, but we weren't sure we could do it by
April, when the observing was scheduled for MIT."
But thanks to Arizona Radio Observatory chief engineer Henry Fagg, the HHT had
its 2mm detector by April.
The astronomers first linked the two Arizona telescopes, which are separated by
100 miles, in 2mm radio observations, Ziurys said. They then tackled the bigger
challenge of linking the U.S. telescopes to Europe. The two Arizona telescopes
and one in Spain provided key long distance detections that were especially
critical to the project.
The telescope has successfully picked up radio signals from galaxies more than 3
billion light years away. It will be used to study one of the fundamental
mysteries of modern astronomy – how so-called "active" galaxies produce their
incredible energetic output.
The Kitt Peak 12 meter radio
telescope (Photo: Lori Stiles)
Normally, galaxies emit as much energy as the
sum of their stars. "Active" galaxies emit far more energy than the sum of their
stars. The excess energy is concentrated at the galaxy's core. Astronomers
believe that super massive black holes, billions of times bigger than the sun,
power these energetic cores. Some of the cores spew powerful streams of
high-speed particles millions of light years beyond their host galaxies. But how
these high-speed particle jets are launched from galactic cores is not clear.
The new telescope is specifically designed to make detailed images of where the
The technique of using several telescopes on different continents to
simultaneously record radio emissions from the same object is called Very Long
Baseline Interferometry (VLBI). Signals from each telescope are time-stamped
with extremely accurate atomic clocks, recorded on magnetic tapes, then combined
in a special-purpose supercomputer. The technique forms a virtual radio
telescope that can be as large as the diameter of Earth.
Future plans are to direct the powerful new telescope at the core of the Milky
Way Galaxy to detect structures close to our galaxy's suspected black hole.
"We weren't sure we could get it to work last spring, but clearly these current
results represent just the tip of the iceberg," Ziurys said. "We are very
excited about future science using this powerful technique."