Sunday, July 14, 2013

Very Large Array

 Text From Wikipedia

The observatory consists of 27 independent antennas, each of which has a dish diameter of 25 meters and weighs 209 metric tons. The antennas are arrayed along the three arms of a Y-shape (each of which measures 21 km/13 miles long). Using the rail tracks that follow each of these arms—and that, at one point, intersect with U.S. Route 60 at a level crossing—and a specially designed lifting locomotive ("Hein's Trein" ), the antennas can be physically relocated to a number of prepared positions, allowing aperture synthesis interferometry with a maximum baseline of 36 km: in essence, the array acts as a single antenna with that diameter. The smallest angular resolution that can be reached is about 0.05 arcseconds at a wavelength of 7 mm.

 
Photo by Samuel E Burns

There are four commonly used configurations, designated A (the largest) through D (the tightest, when all the dishes are within 600 m of the center point). The observatory normally cycles through all the various possible configurations (including several hybrids) every 16 months; the antennas are moved every three to four months. Moves to smaller configurations are done in two stages, first shortening the east and west arms and later shortening the north arm. This allows for a short period of improved imaging of extremely northerly or southerly sources.

   
Photo by Samuel E Burns

The Array Operations Center (AOC) for the VLA is located on the campus of the New Mexico Institute of Mining and Technology in Socorro, New Mexico. The AOC also currently serves as the control center for the Very Long Baseline Array (VLBA), a VLBI array of ten 25-meter dishes located from Hawaii in the west to the U.S. Virgin Islands in the east that constitutes the world's largest dedicated, full-time astronomical instrument.

 
Photo by Samuel E Burns

The Karl G. Jansky Very Large Array (VLA) is a radio astronomy observatory located on the Plains of San Agustin, between the towns of Magdalena and Datil, some fifty miles (80 km) west of Socorro, New Mexico, USA. The VLA has made key observations of black holes and protoplanetary disks around young stars, discovered magnetic filaments and traced complex gas motions at the Milky Way's center, probed the Universe's cosmological parameters, and provided new knowledge about the physical mechanisms that produce radio emission.

 
Photo by Samuel E Burns

The VLA stands at an elevation of 6970 ft (2124 m) above sea level. It is a component of the National Radio Astronomy Observatory (NRAO).

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