Editing Very Long Baseline Array (section)

{{Short description|System of ten radio telescopes}}
{{Infobox observatory}}

The '''Very Long Baseline Array''' ('''VLBA''') is a system of ten [[radio telescope]]s which are operated remotely from their [[Array Operations Center]] located in [[Socorro, New Mexico]], as a part of the [[National Radio Astronomy Observatory]] (NRAO).<ref>{{Cite web|url=https://public.nrao.edu/news/vlba-returning-to-nrao/|title=VLBA Returning to NRAO, Getting Technical Upgrade|website=NRAO eNews|publisher=National Radio Astronomy Observatory|date=2018-10-24|access-date=2019-12-21}}</ref>  These ten [[radio antenna]]s 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 {{convert|8611|km|0|sp=us}}.<ref name=saha2010/>

The construction of the VLBA began in February 1986 and it was completed in May 1993.  The first [[astrometry|astrometrical]] observation using all ten antennas was carried out on May 29, 1993.<ref>{{Cite web|first=Ellen|last=Bouton|url=https://www.nrao.edu/archives/Timeline/timeline.shtml|title=National Radio Astronomy Observatory Archives: NRAO Timeline|publisher=National Radio Astronomy Observatory|date=2019-01-02|access-date=2019-03-31}}</ref>  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.<ref name="SeattleTimes">{{cite news |last1=Lacitis |first1=Erik |title=Seeking the universe from an apple orchard in Brewster |url=https://www.seattletimes.com/seattle-news/seeking-the-universe-from-an-apple-orchard-in-brewster/ |access-date=2018-10-20 |work=The Seattle Times |date=2010-04-28}}</ref>

Each receiver in the VLBA consists of a [[dish antenna|parabolic dish antenna]] 25 [[meter]]s (82 feet) in diameter, along with its adjacent control building. This contains the supporting [[electronics]] and machinery for the receiver, including low-noise electronics, [[digital computer]]s, 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 ton]]s (240 [[short ton]]s).<ref name="SeattleTimes"/>

[[File:VLBA Owens Valley.JPG|thumb|left|The VLBA telescope in [[Owens Valley, California]]]]

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 clock]]s. 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 (geology)|crust of the Earth]] over time, and other small [[measurement error]]s.