The VLA is a radio telescope interferometer consisting of 27 dish antennas arranged in a Y-shaped pattern on the Plains of San Agustin fifty miles west of Socorro, New Mexico, USA. Each antenna weighs about 230 tons and is 25 meters or 81 feet in diameter. The data from each antenna is combined electronically to equal the resolution of an antenna 36km or 22 miles across, with the sensitivity of a dish 130 meters or 422 feet in diameter. Construction of the VLA began in 1973 and the completed project was dedicated during 1980. The VLA is one component of the National Radio Astronomy Observatory ( NRAO ).
The antennas in the VLA can be moved along steel rails by a transport machine. This allows the VLA to zoom in or out on objects. However the process of rearranging the antennas is time consuming and is only done about every four months. In the "A" configuration, the telescopes extend over the 21 kilometer or 13 mile length of each arm. This simulates a single dish that is 36 kilometers or 22 miles in diameter. This configuration yields the highest magnification and greatest detail. The size of the array gradually decreases with the B and C configurations until, in the D configuration, in which the telescopes are all within .6 kilometer or .4 of a mile from the center. In the smaller configurations, scientists can study the overall structure of the source they are observing. By observing the same source in each configuration and combining the data, scientists can gather much more information than from any one configuration alone.
The VLA is currently scheduled for an upgrade known as the Expanded Very Large Array which will incorporate updated electronics, fiber optic connections and possibly eight additional stations as distant as 250 kilometers from the current array. These features will improve the scientific capabilities of the instrument by a factor of 10 in all key observational parameters.
The VLA has always been well known among radio astronomers, but it wasn't until 1997 when the major motion picture Contact brought images of the VLA to the general public en masse. Public tours of the facility are available to those wanting to visit it in person.