Atacama Large Millimeter Array
Telescopes operating in this band include the James Clerk Maxwell Telescope, the Caltech Submillimeter Observatory and the Submillimeter Array at the Mauna Kea Observatory in Hawaii, the BLAST balloon borne telescope, the Herschel Space Observatory, the Heinrich Hertz Submillimeter Telescope at the Mount Graham International Observatory in Arizona, and at the recently built Atacama Large Millimeter Array. Due to Earth's atmospheric absorption spectrum, the opacity of the atmosphere to submillimeter radiation restricts these observatories to very high altitude sites, or to space.