The Caltech Submillimeter Observatory (CSO) is a 10.4 metres (34.1 ft) diameter submillimeter wavelength telescope

Telescope

A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation . The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s , using glass lenses...

 situated alongside the 15 metres (49.2 ft) James Clerk Maxwell Telescope

James Clerk Maxwell Telescope

The James Clerk Maxwell Telescope is a submillimetre-wavelength telescope at Mauna Kea Observatory in Hawaii. Its primary mirror is 15 metres across: it is the largest astronomical telescope that operates in submillimetre wavelengths of the electromagnetic spectrum...

 (JCMT) at Mauna Kea Observatory

Mauna Kea Observatory

The Observatories at Mauna Kea, , are an independent collection of astronomical research facilities located on the summit of Mauna Kea on the Big Island of Hawai'i, USA. The facilities are located in a special land use zone known as the "Astronomy Precinct," which is located in the Mauna Kea...

. It is engaged in submillimeter astronomy, of the terahertz radiation

Terahertz radiation

In physics, terahertz radiation refers to electromagnetic waves propagating at frequencies in the terahertz range. It is synonymously termed submillimeter radiation, terahertz waves, terahertz light, T-rays, T-waves, T-light, T-lux, THz...

 band.

The CSO and JCMT were combined to form the first submillimeter interferometer

Interferometry

Interferometry refers to a family of techniques in which electromagnetic waves are superimposed in order to extract information about the waves. An instrument used to interfere waves is called an interferometer. Interferometry is an important investigative technique in the fields of astronomy,...

. The success of this experiment was important in pushing ahead the construction of the Submillimeter Array

Submillimeter Array

The Submillimeter Array consists of eight diameter radio telescopes arranged as an interferometer for submillimeter wavelength observations. It is the first purpose-built submillimeter interferometer, constructed after successful interferometry experiments using the pre-existing James Clerk...

 and the Atacama Large Millimeter Array

Atacama Large Millimeter Array

The Atacama Large Millimeter/sub-millimeter Array is an array of radio telescopes in the Atacama desert of northern Chile. Since a high and dry site is crucial to millimeter wavelength operations, the array is being constructed on the Chajnantor plateau at 5000 metres altitude...

 interferometers.

On April 30, 2009, Caltech announced plans to decommission the CSO, transferring ongoing research to the next-generation Cerro Chajnantor Atacama Telescope

Cerro Chajnantor Atacama Telescope

The Cerro Chajnantor Atacama Telescope is a proposed 25-metre telescope that is intended to reveal the cosmic origins of stars, planets, and galaxies with its submillimeter cameras and spectrometers enabled by the superconducting detector arrays. Submillimeter is a type of microwave radiation...

(CCAT) in Chile. The plans call for CSO to be dismantled beginning in 2016, with its site returned to a natural state by 2018.