Very Long Baseline Array


The Very Long Baseline Array is a system of ten radio telescopes which are operated remotely from their Array Operations Center located in Socorro, New Mexico, as a part of the National Radio Astronomy Observatory. These ten radio antennas work together as an array that forms the longest system in the world that uses very long baseline interferometry. The longest baseline available in this interferometer is about.
The construction of the VLBA began in February 1986 and it was completed in May 1993. The first astrometrical observation using all ten antennas was carried out on May 29, 1993. The total cost of building the VLBA was about $85 million. The array is funded by the National Science Foundation, and costs about $10 million a year to operate.
Each receiver in the VLBA consists of a parabolic dish antenna 25 meters in diameter, along with its adjacent control building. This contains the supporting electronics and machinery for the receiver, including low-noise electronics, digital computers, data storage units, and the antenna-pointing machinery. Each of the antennas is about as tall as a ten-story building when the antenna is pointed straight up, and each antenna weighs about 218 metric tons.
The signals from each antenna are recorded on a bank of approximately one-terabyte hard disc drives, and the information is time-stamped using atomic clocks. Once the disc drives are loaded with information, they are carried to the Pete V. Domenici Science Operations Center at the NRAO in Socorro. There the information undergoes signal processing in a powerful set of digital computers that carry out the interferometry. These computers also make corrections for the rotation of the Earth, the slight shifts in the crust of the Earth over time, and other small measurement errors.

Observations by the VLBA

The Very Long Baseline Array usually makes radio observations at wavelengths from three millimeters to 90 centimeters, or in other words, at frequencies from 0.3 gigahertz to 96 gigahertz. Within this frequency range, the VLBA observes in eight different frequency bands that are useful for radio astronomy. The VLBA also makes observations in two narrow radio bands below one gigahertz that include spectral lines produced by bright maser emissions.
The VLBA radio telescopes are located at:

High-Sensitivity Array

The use of the VLBA can be scheduled dynamically, and its sensitivity can be improved by a factor of five by including other radio telescopes such as the Arecibo radio telescope in Puerto Rico, the Green Bank Telescope in West Virginia, the Very Large Array in New Mexico and the Effelsberg radio telescope in Germany. These four additional sites are brought online for as much as 100 hours per four-month trimester. In this configuration, the entire array is known as the High-Sensitivity Array.
ToponymStateGeographic coordinate system-
AreciboPuerto RicoAR
Green BankWest VirginiaGB
Very Large ArrayNew MexicoY27
EffelsbergGermanyEB

Baseline distance and angular resolution

Distance between each VLBA baseline : The longest baseline in the array is.
—
SC—285336454143445845794839546057678611682223827084532
HN2853—16113105300632263623388536577502560227488293198
NL36451611—16541432166320752328230061566734346110641640
FD414331051654—608564744150823455134808439222354515
LA445830061432608—236652108817574970783142462344226
PT457932261663564236—4179731806479580144365255152
KP483936232075744652417—84519134466832146232939441
OV54603885232815081088973845—121440158203525533231025
BR57673657230023451757180619131214—43987441558533261849
MK861175026156513449704795446640154398—10328843470284835
EB68225602673480847831801483218203744110328—691163358008
AR2382748346139224246436546235255558584346911—25454317
GB27088291064235423442551293933233326702863352545—2516
Y2745323198164051522652441102518494835800843172516—

Wavelength 905021181364210.7
22125.04.33.21.40.850.470.320.17