SKAThe Square Kilometer Array

Not to be confused with the notion of an array, that is, square and one kilometer on a side, this array w ill have a total collecting area of one square kilometer made up of several thousand small dishes in the 10-15-m diameter range spread over a total area of at least 3,000 km across and capable of operating from 100 MHz to 25 GHz (3 m to 1.2-cm wavelength). About half the collecting area will be concentrated inside a few kilometers to enhance the sensitivity of the array to weaker radio sources and to the radio emission from interstellar HI. To dale, $00 million has been invested in the design and two prototype arrays will be built in Australia and South Africa. Both of these nations are vying to locate the final array within their borders. Other nations hungering for the SK are Argentina and China. Clearly the dry high plains of the western part of South Africa would be ideally suited for the SK. which would place South Africa well and truly on the radio astronomical map. (This is an unbiased statement by this South Africa born author!)

The sensitivity of the SK will be 100 times better than the VLA, which was used to make most of the radiographs in the book. The SK will have a resolution of a thousandth of an arcsecond at a frequency of 20 GHz (wavelength 1.5 cm). With an instrument like that radiographs will look as detailed as the best optical images from the Hubble Space Telescope. One of the drivers behind the construction of the S& is the challenge of observing magnetic fields in distant galaxies, as well as our own of course, where it is clear that up till now we have been resolution-limited in being able to see details.

Back iu 1997 a consortium of nations (Australia, Canada, Chile, India, the Netherlands, and the United States) signed a memorandum of understanding to explore the concept of the SK and the project is being run from the Astronomical Institute in Dwingeloo, the Netherlands. Its anticipated cost is a staggering $.2 billion. But with great patience and a systematic approach to realizing the full array, the radio astronomers involved may yet bring this project to fruition.

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