Plains of San Agustin

The Plains of San Agustin is a broad, high-desert endorheic basin in west-central New Mexico notable for hosting a major radio astronomy facility. The flat, open plain provides radio-quiet conditions that suit long-baseline interferometry.

The single most prominent feature on the plain is the National Radio Astronomy Observatory’s array of radio telescopes. The array comprises 27 radio dishes, each 25 meters in diameter, laid out on rails so the configuration can be changed from compact to very extended formats; the site also includes a visitor center with exhibits and scheduled public access.

The basin was formed by geological and climatic processes and hosted a Pleistocene pluvial lake in prehistory. In the 1970s the National Radio Astronomy Observatory selected the plain for a large interferometric radio telescope; construction progressed through the 1970s with operations beginning around 1980 and later upgrades completed in the 2000s under the Expanded VLA program.

The plain sits in west-central New Mexico, on a broad flat between mountain ranges. The site is approximately west of the small city of Socorro and is reached by rural roads across sparsely settled rangeland.

• Antenna configuration: Array elements are 25 meters across and arranged on railroad tracks that allow configurations from about 1 km to 36 km in baseline length.
• Visitor access: Visitor facilities include a small visitor center with exhibits and public viewing opportunities on scheduled days.

What to See #

• Very Large Array: Located on the plain and consisting of 27 dish antennas each 25 meters in diameter; original construction took place in the 1970s with first operations in 1980, and the array was upgraded under the Expanded VLA program (completed in the 2000s) and is now known as the Karl G. Jansky Very Large Array.