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The Epic Interactive Encyclopedia 1998
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Epic Interactive Encyclopedia, The - 1998 Edition (1998)(Epic Marketing).iso
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Very_Large_Array,_VLA
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1992-09-01
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29 lines
The largest and most complex single-site
radio telescope in the world. It is located
on the Plains of San Augustine, 80 km/50 mi
west of Socorro, New Mexico. It consists of
27 dish antennae, each 25 m/82 ft in
diameter, arranged along three equally spaced
arms forming a Y-shaped array. Two of the
arms are 21 km/13 mi long, and the third, to
the north, is 19 km/11.8 mi long. The dishes
are mounted on railway tracks enabling the
configuration and size of the array to be
altered as required. There are four standard
configurations of antennae ranging from A
(the most extended) through B and C to D. In
the A configuration the antennae are spread
out along the full extent of the arms and the
VLA can map small, intense radio sources with
high resolution. The smallest configuration,
D, uses arms that are just 0.6 km/0.4 mi long
for mapping larger sources. Here the
resolution is lower, although there is
greater sensitivity to fainter, extended
fields of radio emission. Pairs of dishes can
also be used as separate interferometers (see
radio telescope), each dish having its own
individual receivers that are remotely
controlled, enabling many different
frequencies to be studied.