Definition
The Very Large Array (VLA) is a radio astronomy observatory consisting of 27 independent antenna dishes arranged in a Y-shaped configuration, operated by the National Radio Astronomy Observatory (NRAO) in the United States.
Overview
Located on the Plains of San Agustin in the central desert region of New Mexico, the VLA is one of the world’s pre‑eminent interferometric radio telescopes. Each of the 27 dish antennas has a diameter of 25 metres (82 ft). By combining the signals from these antennas using aperture synthesis, the VLA can achieve the resolving power of a single dish up to 36 km (22 mi) in diameter, depending on the chosen array configuration. Since its completion in 1980, the VLA has contributed to a broad range of astrophysical research, including studies of pulsars, quasars, interstellar molecular clouds, and the cosmic microwave background.
Etymology/Origin
The name “Very Large Array” reflects both the physical scale of the instrument and its design as an array of multiple radio antenna elements. The term “array” is standard in radio astronomy for a collection of antennas whose signals are combined interferometrically. The adjective “very large” distinguishes it from earlier, smaller interferometers built in the 1950s and 1960s.
Characteristics
| Feature | Description |
|---|---|
| Number of Antennas | 27 |
| Antenna Diameter | 25 m (82 ft) |
| Maximum Baseline | 36 km (22 mi) in the “A” configuration |
| Frequency Range | 1 GHz – 50 GHz (approximately 30 cm to 0.7 cm wavelength) |
| Configurations | Four standard configurations (A, B, C, D) with baselines of 36 km, 11 km, 3.4 km, and 1 km respectively; the array is reconfigured every 16 months. |
| Resolution | Up to 0.04 arcseconds at the highest frequencies in the A configuration. |
| Sensitivity | System temperature typically 30–50 K; continuum sensitivity ≈ 2 µJy beam⁻¹ in 12 h at 1.4 GHz. |
| Control & Data Processing | Managed by NRAO; data are processed using the Common Astronomy Software Applications (CASA) package. |
| Operating Institution | National Radio Astronomy Observatory, a facility of the National Science Foundation. |
| Public Access | Observing time allocated through peer‑reviewed proposals; data become publicly available after a proprietary period (usually 12 months). |
Related Topics
- Aperture Synthesis – The technique employed by the VLA to simulate a larger aperture by combining signals from multiple antennas.
- National Radio Astronomy Observatory (NRAO) – The U.S. organization that operates the VLA and other major radio facilities.
- Karl G. Jansky Very Large Array (JVLA) – The upgraded version of the VLA, completed in 2012, featuring new receivers, electronics, and a broader frequency coverage.
- Radio Interferometry – The broader class of observational methods that includes the VLA, used to achieve high angular resolution at radio wavelengths.
- Square Kilometre Array (SKA) – A forthcoming international radio telescope array that will vastly exceed the collecting area of the VLA.
This entry reflects information reliable as of 2024. No unverified claims are presented.