The James Clerk Maxwell Telescope (JCMT) is a 15-metre submillimetre-wavelength telescope 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 Observatories at Mauna Kea are an independent collection of the worlds premier astronomical research facilities, located on the summit of Mauna Kea on the Big Island of Hawaii, USA. The facilities are located in a 500-acre special land use zone known as the Astronomy Precinct, which... Official language(s) English, Hawaiian Capital Honolulu Largest city Honolulu Area  Ranked 43rd  - Total 10,931 sq mi (29,311 km²)  - Width n/a miles (n/a km)  - Length 1,522 miles (2,450 km)  - % water 41. ... Submillimetre Astronomy is the branch of observational astronomy that is conducted at submillimetre wavelengths. ... Far infrared astronomy is the branch of astronomy and astrophysics which deals with objects visible in far-infrared radiation (approximatively from 30μm to 300μm). ... Microwaves are electromagnetic waves with wavelengths longer than those of terahertz (THz) frequencies, but relatively short for radio waves. ... Legend γ = Gamma rays HX = Hard X-rays SX = Soft X-Rays EUV = Extreme ultraviolet NUV = Near ultraviolet Visible light NIR = Near infrared MIR = Moderate infrared FIR = Far infrared Radio waves EHF = Extremely high frequency (Microwaves) SHF = Super high frequency (Microwaves) UHF = Ultra high frequency VHF = Very high frequency HF = High... Major features of the Solar System (not to scale; from left to right): Pluto, Neptune, Uranus, Saturn, Jupiter, the asteroid belt, the Sun, Mercury, Venus, Earth and its Moon, and Mars. ... NGC 4414, a typical spiral galaxy in the constellation Coma Berenices, is about 17,000 parsecs in diameter and approximately 20 million parsecs distant. ...

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 4092 meters as part of the Mauna Kea Observatory. The JCMT has the second largest telescope mirror on Mauna Kea (largest is the VLBA antenna). The Joint Astronomy Centre (JAC) operates British, Canadian and Dutch telescopes at Mauna Kea Observatory, and provides support for other telescopes and public outreach activities. ... James Clerk Maxwell (13 June 1831 – 5 November 1879) was a Scottish mathematician and theoretical physicist. ... The Observatories at Mauna Kea are an independent collection of the worlds premier astronomical research facilities, located on the summit of Mauna Kea on the Big Island of Hawaii, USA. The facilities are located in a 500-acre special land use zone known as the Astronomy Precinct, which... VLBA locations. ...

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. The Caltech Submillimeter Observatory (or CSO) is a 10. ... Interferometry is the applied science of combining two or more input points of a particular data type, such as optical measurements, to form a greater picture based on the combination of the two sources. ... The submillimeter array under construction in 2002 The Submillimeter Array consists of 8 6 m diameter radio telescopes arranged as an interferometer for submillimeter wavelength observations. ... The Atacama Large Millimeter Array (ALMA) is an international astronomy project that consists of a system of radio telescopes in an array formation, located at Llano de Chajnantor Observatory in the Atacama desert in northern Chile. ...

History

In the late 1960s the Astronomy Committee of the UK's Science Research Council (SRC, the forerunner of SciTech) considered the importance of astronomical observations at submillimetre and millimetre wavelengths. A series of proposals and debates led, in 1975, to the SRC millimetre steering committee concluding 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. A program of site tests considered Mauna Kea in Hawaii, the Pinaleno Mountains in Arizona, and a site in Chile. Ultimately Mauna Kea was chosen as the preferred site. The NNTT is a unique facility, both larger and with a more extensive instrument suite than competing telescopes such as the CSO and SMT. The Research Councils of the UK are government agencies responsible for particular areas of science and technology. ... Science and Technology Facilities Council Logo The Science and Technology Facilities Council (or Scitech) is a UK government body that carries out civil research in science and engineering, and funds UK research in areas including particle physics, nuclear physics, space science and astronomy. ... A micrometre (American spelling: micrometer, symbol µm) is an SI unit of length equal to one millionth of a metre, or about a tenth of the diameter of a droplet of mist or fog. ... Mauna Kea is a dormant volcano in the Hawaiian Islands, one of five volcanic peaks that together form the island of Hawaii. ... Official language(s) English, Hawaiian Capital Honolulu Largest city Honolulu Area  Ranked 43rd  - Total 10,931 sq mi (29,311 km²)  - Width n/a miles (n/a km)  - Length 1,522 miles (2,450 km)  - % water 41. ... Arizonas Pinaleño Mountains. ... Official language(s) English Spoken language(s) English 74. ... The Caltech Submillimeter Observatory (or CSO) is a 10. ... The Submillimeter Telescope (SMT), formerly known as the Heinrich Hertz Submillimeter Telescope, is a submillimeter wavelength radio telescope located on Mount Graham, Arizona. ...

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. A Yagi-Uda beam antenna Short Wave Curtain Antenna (Moosbrunn, Austria) A building rooftop supporting numerous dish and sectored mobile telecommunications antennas (Doncaster, Victoria, Australia) An antenna is a transducer designed to transmit or receive radio waves which are a class of electromagnetic waves. ... An Altazimuth or alt-azimuth mount is a simple mount used for moving a telescope or camera along two perpendicular axes of motion. ... Light path in a Cassegrain reflector Laurent Cassegrain was a catholic priest born in the region of Chartres around 1629 and died at Chaudon (Eure-et-Loir) on August 31, 1693. ... Year 1983 (MCMLXXXIII) was a common year starting on Saturday (link displays the 1983 Gregorian calendar). ... For other meanings of Pacific, see Pacific (disambiguation). ... Pirates may refer to: A group of people committing any of these activities: Piracy at sea or on a river/lake. ... Year 1987 (MCMLXXXVII) was a common year starting on Thursday (link displays 1987 Gregorian calendar). ...

The JCMT is currently funded under a tripartite agreement between the United Kingdom (55 per cent), Canada (25 per cent), and the Netherlands (20 per cent). The telescope itself is operated by the Joint Astronomy Centre (JAC), from Hilo, Hawaii. The telescope site agreement with the University of Hawaii provides observer accommodation and infrastructure in exchange for open access to international proposals and 10 per cent of the observing time for the University's own projects. Proposals for telescope usage are submitted to one of the national Telescope Allocation Groups (TAGs) and if successful are awarded time in the next six-monthly semester. The Joint Astronomy Centre (JAC) operates British, Canadian and Dutch telescopes at Mauna Kea Observatory, and provides support for other telescopes and public outreach activities. ... Hilo is the largest town on the island of Hawai‘i, and the county seat of Hawai‘i County, Hawai‘i. ... This article is about the University of Hawaii system. ...

Instrumentation

The JCMT carries two types of instruments—broadband continuum detectors and heterodyne detection spectral-line receivers. Captain Nemo and Professor Aronnax contemplating measuring instruments in Twenty Thousand Leagues Under the Sea In physics and engineering, measurement is the activity of comparing physical quantities of real-world objects and events. ... Broadband in telecommunications is a term which refers to a signaling method which includes or handles a relatively wide range of frequencies which may be divided into channels or frequency bins. ... Look up continuum in Wiktionary, the free dictionary. ... A detector is a device that detects or measures some phenomenon or stimulus, and produces some signal in response. ... Heterodyne detection is a method of detecting frequency-modulated radiation by non-linear mixing with radiation of a reference frequency. ...

The older continuum single pixel UKT14 bolometer receiver was replaced in the 1990s by the Submillimetre Common Users Bolometer Array (SCUBA). The SCUBA project was greenlighted in 1987 by the JCMT board and was in development for nearly a decade before it saw first light on the telescope. While it was not the first bolometer-array it was "unique in combining an unparallel sensitivity with an extensive wavelength range and field-of-view" [1]. Rendition of an imaging bolometer from Los Alamos National Laboratory A bolometer is a device for measuring incident electromagnetic radiation. ...

SCUBA is sensitive to the thermal emission from interstellar dust. This 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 nurserys and planet forming solar systems.

SCUBA is ranked second only to the Hubble Space Telescope in terms of publication of high-impact astronomical research. SCUBA was retired from service in 2005. Work is currently underway on SCUBA-2, a replacement for SCUBA, that is expected to see first light in Aug 2007.

The JCMT is also equipped with three heterodyne receivers, which allow submillimetre spectral-line observations to be made. Spectral-line observations can be used to identify particular molecules in the interstellar medium and determine local gas velocity gradients across astronomical objects of interest. The spectral-line mapping capabilities of the JCMT have been greatly enhanced by the commissioning of HARP-B, a 350 GHz, 16 element heterodyne array receiver. HARP-B, and the other heterodyne instruments, can be used in conjunction with the JCMT's new digital autocorrelation spectrometer, ACSIS. In telecommunications, to heterodyne is to generate new frequencies by mixing two or more signals in a nonlinear device such as a vacuum tube, transistor, or diode mixer. ...

See also

• Infrared astronomy
• Submillimetre astronomy
• Far infrared astronomy
• Radio astronomy

Infrared astronomy is the branch of astronomy and astrophysics which deals with objects visible in infrared (IR) radiation. ... Submillimetre Astronomy is the branch of observational astronomy that is conducted at submillimetre wavelengths. ... Far infrared astronomy is the branch of astronomy and astrophysics which deals with objects visible in far-infrared radiation (approximatively from 30μm to 300μm). ... The Very Large Array, a radio interferometer in New Mexico, USA Radio astronomy is a subfield of astronomy that studies celestial objects in the radio frequency portion of the electromagnetic spectrum. ...

External links

• JCMT homepage
• JCMT on wikimapia