VERY LARGE ARRAY

(VLA) radio telescope system situated on the plains of San Augustin near Socorro, New Mexico, U.S. The VLA went into operation in 1980 and is the most powerful radio telescope in the world. It is operated by the National Radio Astronomy Observatory. The VLA consists of 27 parabolic dishes that are each 25 m (82 feet) in diameter. Each of these dishes is mounted on a transporter that can be moved along rails laid out in an enormous Y pattern. (The arms of this pattern extend about 21 km [13 miles] each.) The resolution of the VLA is altered by changing the positions of the dishes. The radio signals recorded by the component dishes are integrated by computer so that the entire array acts as a single radio antenna with a maximum effective aperture of 27 km (17 miles). This large aperture gives the VLA a resolving power equal to that of the best ground-based optical telescopes.