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| Alternative names | VLA |
|---|---|
| Location(s) | Socorro County,New Mexico |
| Coordinates | 34°04′43″N107°37′04″W / 34.0787492°N 107.6177275°W /34.0787492; -107.6177275 |
| Altitude | 2,124 m (6,969 ft) |
| Wavelength | 0.6 cm (50 GHz)–410 cm (73 MHz) |
| Built | 1973–1981 |
| Diameter | |
| Website | science |
  Location of the Very Large Array | |
 Related media on Commons | |
TheKarl G. Jansky Very Large Array (VLA) is a centimeter-wavelengthradio astronomy observatory in the southwestern United States built in the 1970s. It lies in centralNew Mexico on thePlains of San Agustin, between the towns ofMagdalena andDatil, approximately 50 miles (80 km) west ofSocorro. The VLA comprises 28 25-meter (82 ft) radio telescopes (27 of which are operational while one is always rotating through maintenance) deployed in a Y-shaped array and all the equipment, instrumentation, and computing power to function as aninterferometer. Each of the massive telescopes is mounted on double parallel railroad tracks, so the radius and density of the array can be transformed to adjust the balance between its angular resolution and its surface brightness sensitivity.[2] Astronomers using the VLA have made key observations ofblack holes andprotoplanetary disks aroundyoung stars, discovered magnetic filaments and traced complex gas motions at theMilky Way's center, probed the Universe's cosmological parameters, and provided new knowledge about the physical mechanisms that produceradio emission.
The VLA stands at an elevation of 6,970 feet (2,120 m) above sea level. It is a component of theNational Radio Astronomy Observatory (NRAO).[3] The NRAO is a facility of theNational Science Foundation operated under cooperative agreement byAssociated Universities, Inc.
Theradio telescope comprises 27 independent antennas in use at a given time plus one spare, each of which has a dish diameter of 25 meters (82 feet) and weighs 209metric tons (230short tons).[2] The antennas are distributed along the three arms of a track, shaped in a wye (or Y-shaped) configuration, each of arm measuring 21 kilometers (13 mi) long. Using the rail tracks that follow each of these arms—and that, at one point, intersect withU.S. Route 60 at a level crossing—and a specially designed lifting locomotive ("Hein's Trein"),[4] the antennas can be physically relocated to a number of prepared positions, allowingaperture synthesisinterferometry with up to 351 independent baselines: in essence, the array acts as a single antenna with a variable diameter. Theangular resolution that can be reached is between0.2 and 0.04 arcseconds.[5]
There are four commonly used configurations, designated A (the largest) through D (the tightest, when all the dishes are within 600 meters (2,000 ft) 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.[6][7]
The frequency coverage is74 MHz to50 GHz (400 to 0.7 cm).[8][better source needed]
The Pete V. Domenici ScienceOperations Center (DSOC) for the VLA is located on the campus of theNew Mexico Institute of Mining and Technology inSocorro, New Mexico. The DSOC also serves as the control center for theVery Long Baseline Array (VLBA), aVLBI array of ten 25-meter (82 ft) dishes located fromHawaii in the west to theU.S. Virgin Islands in the east that constitutes the world's largest dedicated, full-time astronomical instrument.[9]
The VLA is a multi-purpose instrument designed to allow investigations of many astronomical objects, includingradio galaxies,quasars,pulsars,supernova remnants,gamma-ray bursts, radio-emittingstars, thesun andplanets,astrophysical masers,black holes, and thehydrogen gas that constitutes a large portion of theMilky Way galaxy as well as external galaxies. In 1989 the VLA was used to receiveradio communications from theVoyager 2 spacecraft as it flew byNeptune.[10] A search of the galaxies M31 and M32 was conducted in December 2014 through January 2015 with the intent of quickly searching trillions of systems for extremely powerful signals from advanced civilizations.[11]
It has been used to carry out several large surveys of radio sources, including theNRAO VLA Sky Survey andFaint Images of the Radio Sky at Twenty-Centimeters.
In September 2017 theVLA Sky Survey (VLASS) began.[12] This survey will cover the entire sky visible to the VLA (80% of the Earth's sky) in three full scans.[13] Astronomers expect to find about 10 million new objects with the survey – four times more than what is presently known.[13]
The driving force for the development of the VLA wasDavid S. Heeschen. He is noted as having "sustained and guided the development of the best radio astronomy observatory in the world for sixteen years."[14]Congressional approval for the VLA project was given in August 1972, and construction began some six months later. The first antenna was put into place in September 1975 and the complex was formally inaugurated in 1980, after a total investment of $78.5 million[8] (equivalent to $250 million in 2024).[15] It was the largest configuration of radio telescopes in the world.
In 1997 the VLA featured inContact, the film adaptation of the 1985book by the same name written byCarl Sagan.[16][17][18]
With a view to upgrading the venerable 1970s technology with which the VLA was built, the VLA has evolved into the Expanded Very Large Array (EVLA). Beginning in 2001, the upgrade has enhanced the instrument's sensitivity,frequency range, and resolution with the installation of new hardware at the San Agustin site. The project was completed on time and on budget in 2012.[19] A second phase of this upgrade may add up to eight additional antennae in other parts of the state ofNew Mexico, up to 190 miles (300 km) away, if funded.[20]
The decade-long EVLA upgrade project resulted in the VLA expanding its technical capacities by factors of up to 8,000. The 1970s-era electronics were replaced with state-of-the-art equipment. To reflect this increased capacity, VLA officials asked for input from both the scientific community and the public in coming up with a new name for the array, and near the completion of the EVLA project in January 2012 it was announced that the array would be renamed the "Karl G. Jansky Very Large Array".[21][22][23] On March 31, 2012, the VLA was officially renamed in a ceremony inside the Antenna Assembly Building.[24]
In June 2023, theNational Radio Astronomy Observatory announced that they will be replacing the ageing antennae with 160 new ones at the site, plus 100 auxiliary antennae located across North America. The project, estimated to cost about $2 billion to build and around $90 million to run, will vastly expand the capabilities of the current installation and increase the frequency sensitivity from50 GHz to over100 GHz. The facility will be renamed theNext Generation Very Large Array (ngVLA).[25][26]
Upgrading to the ngVLA will begin in late 2028 and early science operation will begin in mid 2031.[27] This upgrade will replace the old antennae with more than 260 new antennae.[28] These will be 18 meters in diameter and have three configurations:[29]
The ngVLA will be ten times more sensitive than the old VLA and ten times more sensitive than ALMA. It will operate at1.2–116 GHz.[31] A prototype antenna was produced by the German companymtex antenna technology inSchkeuditz, Saxony[32] and panels made by CONCAD inWalldürn.[33] The prototype dish was installed on its pedestal on February 6, 2025.[34]
A project led by theUniversity of Würzburg will build theWetterstein Millimeter Telescope (WMT)[35] on top of theZugspitze, near theSchneefernerhaus. The newradio telescope will be part of the ngVLA, as the German contribution to the ngVLA. The WMT will also be able to do observations on its own.[28][36]
The VLA is located between the towns ofMagdalena andDatil, about 50 miles (80 km) west ofSocorro, New Mexico.U.S. Route 60 passes east–west through the complex.[37]
The VLA site is open to visitors with paid admission.[3] A visitor center houses a small museum, theater, and a gift shop. A self-guided walking tour is available, as the visitor center is not staffed continuously. Visitors unfamiliar with the area are warned that there is little food on site, or in the sparsely populated surroundings; those unfamiliar with the high desert are warned that the weather is quite variable, and can remain cold into April.[3] For those who cannot travel to the site, the NRAO created a virtual tour of the VLA called theVLA Explorer.[38]
The VLA site was previously closed to visitors from March 2020 through October 2022.[39][40]
All our facilities are CLOSED to the public!
| Authority control databases: National |
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