VLA The Very Large Array

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VLA -The Very Large Array

• Jian Wu Brendan Miller
• For ASTRO513
• 12 December 2009

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(No Transcript)
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In retrospect

• Time Line
• 1972 August approved by Congress
• 1973 April construction started
• 1975 September 22 first antenna put in place
• 1976 February 18 first fringes
• 1980 formal dedication of the VLA
• Total cost - 78,578,000 (in 1972 dollars)
• roughly 1 per taxpayer at the time

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Technical Parameters

• How many?
• 27 antennas
• How big?
• ? 25 m
• How sensitive?
• ?eff 130 m
• Fmin(43GHz) 0.25mJy
• How resolvable?
• ?? (43GHz) 0.04?
• ?eff 36km

• Waveband
• 74 - 50,000 MHz (400 - 0.7 cm)

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Technical Details - Configurations
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• 4 Pure Y
• A array - L 36 km
• B array - L 10 km
• C array - L 3.6 km
• D array - L 1 km
• Period 4 months
• 3 hybrid' configurations
• DnC, CnB, and BnA

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VLA Example - 3C433
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Technical Details - Receivers
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Technical Details - u-v plane
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Technical Details - u-v plane
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Technical Details - u-v plane
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Technical Details - u-v plane
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Technical Details - u-v plane
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Technical Details - Pie Town Extension

• Fiber optic link to Pie Town, 32 Miles from VLA
• Uses one of the VLBA antennas
• Doubles resolution of VLA
• Available for scientific use May 2003

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Science of VLA

• FIRST
• Faint Images of the Radio Sky at
  Twenty-centimeters
• Flx limit 1mJy
• Resolution limit 5?
• 90/sq degree
• Coincide with SDSS

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Science of VLA

• NVSS (1993.9-1996.10)
• NRAO VLA Sky Survey
• Configuration D and DnC
• F 1.4 GHz
• ?gt-40
• Completeness limit 2.5 mJy
• Resolution ? 45?
• 1.8 ?106 sources

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New Development

• EVLA (The Expanded VLA Project)
• Sensitivityf f present /(520) Point souce
  f (240GHz)lt1 ?Jy
• Frequency Accessibility 1.050 GHz / 74 - 50,000
  MHz 8 GHz bandwidth per polarization
• ResolutionAngular resolution up to 200 /
  (frequency in GHz) milli-arcseconds

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VLA -The Very Large Array
THANK YOU