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The environment of the Antarctic Plateau affords a number of unique advantages for earth-based astronomical observations. Its high altitude and extreme arridity assure high atmospheric transparency at infrared and submillimeter wavelengths. Its low temperatures minimize ambient thermal emission. Its climate, dominated by an extremely stable atmospheric circulation system, results in extended periods of consistently excellent observing conditions. Within the interior of the high plateau, wind velocities are small at both low and high altitudes; the surface topography is flat and smooth; and, during the polar winter, the temperature inversion between troposphere and stratosphere disappears. Along with the consistent dryness of the air, these conditions may allow astronomers to exploit technological advances in interferometry and adaptive optics to make observations with higher angular resolution than from aywhere else on earth. A large fraction of the sky never rises or sets, allowing very long, continuous observations of variable phenomena. The high geomagnetic latitude permits observations of low-energy cosmic rays. Finally, tests have recently demonstrated that the polar ice sheet itself can serve as a Cerenkov detector for high-energy muons and neutrinos.
The first major astrophysics experiments to be pursued from the South Pole were observations of cosmic rays and solar oscillations. More recently, a number of groups have initiated efforts to detect and map anisotropies in the cosmic microwave background radiation.
The Center for Astrophysical Research in Antarctica, a National Science Foundation Science and Technology Center, was created in 1991 to establish an astronomical observatory at the South Pole. Its scientific focus is the investigation of the formation of structure in the universe through observations at infrared and submillimeter wavelengths. Instrumentation now under development includes two specialized telescopes for observations of the cosmic microwave background radiation, a highly automated 1.7-m submillimeter telescope which will conduct surveys of line-radiation from interstellar molecules, and a 0.6-m near infrared telescope designed to characterize and exploit a uniquely dark spectral window centered near a wavelength of 2.4 microns. The Center is also conducting tests of site quality, establishing laboratories and other infrastructure to support year-round observations, and planning for advanced telescopes and instrumentation.
Work has also begun this year on another major new initiative, the Antarctic Muon and Neutrino Detector Array. This project will use a large-volume Cerenkov telescope based on photodectors deployed in kilometer-deep holes in the polar ice sheet to search for neutrinos from sources in the northern celestial hemisphere.
If these exploratory ventures are successful, telescopes at the South Pole and other even higher sites on the Antarctic plateau may become the premiere tools for a broad range of earth-based astronomical observations during the twenty-first century.
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