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The James Clerk Maxwell Telescope (JCMT) is a submillimetre-wavelength telescope at Mauna Kea Observatory in Hawaii. The telescope is near the summit of Mauna Kea at . Its primary mirror is 15 metres (16.4 yards) across: it is the largest astronomical telescope that operates in submillimetre wavelengths of the electromagnetic spectrum (far-infrared to microwave).〔W.S. Holland et al., SCUBA: a common-user submillimetre camera operating on the James Clerk Maxwell Telescope, Monthly Notices of the Royal Astronomical Society: Letters Volume 303 Issue 4, Pages 659–672, 2002 〕 Scientists use it to study our Solar System, interstellar dust and gas, and distant galaxies. The JCMT was funded until February 2015 by a partnership between the United Kingdom and Canada, and the Netherlands. It was operated by the Joint Astronomy Centre and was named in honour of mathematical physicist James Clerk Maxwell. From March 2015 the operation of the JCMT is taken over by the East Asian Observatory.〔(【引用サイトリンク】title=East Asian Observatory - Hilo, Hawaii )〕 The JCMT has the second-largest telescope mirror on Mauna Kea. (The largest is the VLBA antenna.) The telescope was combined with the Caltech Submillimeter Observatory next to it to form the first submillimetre interferometer. This success was important in pushing ahead the construction of the Submillimeter Array and the Atacama Large Millimeter Array interferometers. ==History== In the late 1960s, the Astronomy Committee of the UK's Science Research Council (SRC, the forerunner of STFC) considered the importance of astronomical observations at submillimetre and millimetre wavelengths. After a series of proposals and debates, in 1975, the SRC millimetre steering committee concluded that it would be possible to construct a 15-metre diameter telescope capable of observing at wavelengths down to 750 µm. The project, then called the National New Technology Telescope (NNTT), was to be an 80/20 per cent collaboration with the Netherlands Organisation for the Advancement of Science. Site tests were made at Mauna Kea in Hawaii, the Pinaleno Mountains in Arizona, and a site in Chile; and Mauna Kea was chosen. The NNTT is a unique facility, larger and with a more instruments than competing telescopes such as the CSO and SMT. The final specifications called for the "world's largest telescope optimised for submillimetre wavelengths". It was to be a parabolic 15-metre antenna composed of 276 individually adjustable panels with a surface accuracy of better than 50 µm. It would be an altitude-azimuth mounted Cassegrain telescope with a tertiary mirror to direct the incoming radiation onto a number of different receivers. The antenna and mountings were to be protected from the elements by a co-rotating carousel with a transparent membrane stretched across the carousel aperture. Building work started in 1983 and went well apart from a small delay caused by the hijacking of the ship carrying the telescope across the Pacific by modern-day pirates. The telescope saw first light in 1987. The name for the final facility was changed to the James Clerk Maxwell Telescope. The JCMT was until February 2015 funded under an agreement between the United Kingdom (75 percent) and Canada (25 percent) (until March 31, 2013 this was United Kingdom (55 percent), Canada (25 percent), the Netherlands (20 percent)). The telescope itself was operated by the Joint Astronomy Centre (JAC), from Hilo, Hawaii. Since March 2015 the JCMT is operated by the East Asian Observatory, which is funded by Japan, China, Taiwan, and South-Korea, together with consortia of Universities from the United Kingdom and Canada. ==Instrumentation== The JCMT has two kinds of instruments—broadband continuum receivers and heterodyne detection spectral line receivers. Continuum emission is a tracer of star formation in other galaxies and gives astronomers clues to the presence, distance, and evolution history of galaxies other than our own. Within our own galaxy dust emission is associated with stellar nurseries and planet forming solar systems. Spectral-line observations can be used to identify particular molecules in molecular clouds, study their distribution and chemistry and determine gas velocity gradients across astronomical objects (because of the doppler effect). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「James Clerk Maxwell Telescope」の詳細全文を読む スポンサード リンク
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