The James Clerk Maxwell Telescope (JCMT) is a submillimetre-wavelength telescope with a primary mirror diameter of 15 metres (16.4 yards). It is located at Mauna Kea Observatory in Hawaii. It is the largest astronomical telescope in the world designed specifically to operate in the submillimetre regime (between the far-infrared and the microwave regions of the electromagnetic spectrum). It is used to study our Solar System, interstellar dust and gas, and distant galaxies.
The JCMT is funded by a partnership between the United Kingdom, Canada, and the Netherlands. It is operated by the Joint Astronomy Centre and was named in honour of James Clerk Maxwell. It is located near the summit of Mauna Kea at an altitude of 13,425 feet (4092 m) as part of the Mauna Kea Observatory. The JCMT has the second largest telescope mirror on Mauna Kea (largest is the VLBA antenna).
This telescope was combined with the Caltech Submillimeter Observatory to form the first submillimeter interferometer. The success of this experiment was important in pushing ahead the construction of the Submillimeter Array and the Atacama Large Millimeter Array interferometers.