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National Radio Astronomy Observatory
P.O. Box O
Socorro, New Mexico 87801

NRAO Background Information


Dave Finley, Public Information Officer
(505) 835-7302

The Very Long Baseline Array (VLBA)

A continent-wide radio telescope system offering the greatest resolving power of any astronomical instrument operational today

Overview: The National Science Foundation's VLBA is a system of ten identical radio-telescope antennas controlled from a common headquarters and working together as a single instrument. The radio signals received by each individual antenna contribute part of the information used to produce images of celestial objects with hundreds of times more detail than Hubble Space Telescope images.

Scientific Areas: The VLBA can contribute to any astronomical research area where quality, high-resolution radio images will advance knowledge of the field. In its first five years of full operation, the VLBA has produced dramatic new information in these areas:

Operations: The VLBA is operated from the National Radio Astronomy Observatory's (NRAO) Array Operations Center (AOC) in Socorro, New Mexico. The staff of the AOC also supports the Very Large Array, a system of 27 antennas 50 miles west of Socorro. The NRAO is a facility of the National Science Foundation, and its instruments, including the VLBA, are available to the scientific community on a peer-reviewed basis. Scientists whose observing proposals are successful can obtain extensive assistance from NRAO astronomers and technical staff in preparing for their observations and in processing their data after the observations. Through this process, numerous graduate students now are using the VLBA for their dissertation research.

History: Construction of the VLBA began in 1986, and the last observing station was completed in 1993. Astronomical observations with the partially-completed system began in 1987. All 10 VLBA stations were used for observing the first time in May of 1993. The official opening of the VLBA was held in Socorro, NM, on August 20, 1993. The total cost of constructing the VLBA was $85 million.

Stations: The VLBA has stations at: St. Croix, U.S. Virgin Islands; Hancock, New Hampshire; North Liberty, Iowa; Fort Davis, Texas; Los Alamos, New Mexico; Pie Town, New Mexico; Kitt Peak, Arizona; Owens Valley, California; Brewster, Washington; and Mauna Kea, Hawaii.

Technical Data: The VLBA's 240-ton dish antennas are 25 meters (82 feet) in diameter. They are equipped with receivers capable of detecting signals at frequencies ranging from 300 MegaHertz to 86 GigaHertz in non-continuous bands. During observations, data is collected at each station and recorded on magnetic tape. Each 18,000-foot reel of this tape holds 750 GBytes of data. Following observation, the tapes are shipped to Socorro. In Socorro, the VLBA Correlator, a special-purpose digital machine that combines the signals from all antennas, can perform 750 billion mathematical operations per second. The VLBA can produce images with a resolution of less than a thousandth of a second of arc. Such resolution is the equivalent of being able to stand in New York and read a newspaper in Los Angeles. The VLBA routinely works with other radio telescopes elsewhere in the world and in space.

For More Information, See the VLBA Web Site