ARO 12m Radio Telescope

The original dish was built in 1967 under the umbrella of the National Radio Astronomy Observatory (NRAO). At that time, it was 36 ft in diameter and was known as the 36-foot Telescope. In 1984, it was renovated with a new backup structure and a slightly larger dish. At this point its name was changed to the 12 Meter Telescope. In 2000, the NRAO passed control of the telescope to the University of Arizona. The University of Arizona had been operating the Submillimeter Telescope (SMT) located on Mount Graham since 1992. When it took over operations of the 12m, it created the Arizona Radio Observatory (ARO), a part of Steward Observatory of the UArizona College of Science, which now runs both telescopes. In 2013, the entire antenna (dish and mounting) was replaced with ESO's ALMA prototype antenna, which had been located in New Mexico. The new antenna is the same size (12 meters) but has a much better surface accuracy (thereby permitting use at shorter wavelengths), and a more precise mount with better pointing accuracy.

This table displays some of the characteristics of the telescope and the site. • Site • East Longitude — -111° — 36' — 53.475" • North Latitude — +31° — 57' — 12.000" • Elevation — 1914 m (6280 ft) • Telescope • Primary Reflector Diameter — 12.0 m • Focal Ratio (f/D) — Prime = 0.4, Cassegrain = 8.0 • Surface Accuracy — better than 60 μm rms • Mount — Elevation over Azimuth • Slew Rate — 6.0°/minute • Pointing Accuracy — 2" rms • Elevation Limit — 3° • Enclosure — Tracking astrodome with movable door

In the almost 40 years since it was first built, the 12m Radio Telescope has been at the forefront of millimeter molecular astronomy: studying molecules in space through the use of molecular spectroscopy at millimeter wavelengths. Many of the molecules that have been discovered in the interstellar medium were discovered by the 12m.