Giant Magellan Telescope
Encyclopedia
The Giant Magellan Telescope (GMT) is a ground-based extremely large telescope
planned for completion in 2018. It will consist of seven 8.4 m (27.6 ft) diameter primary segments, with the resolving power of a 24.5 m (80.4 ft) primary mirror and collecting area equivalent to 21.4 m (70.2 ft) one. The telescope is expected to have over four times the light-gathering ability of existing instruments.
, which is also the site of the Magellan telescopes, some 115 km (71 mi) north-northeast
of La Serena, Chile. Much as for previous notable telescopes, the site has been chosen as the new instrument's location because of its clear weather throughout most of the year. Moreover, due to the sparsity of population centers and other favorable geographical conditions, the night sky in most of the surrounding Atacama Desert
region is not only free from atmospheric pollution
, but in addition it is probably one of the places least affected by light pollution, making the area one of the best spots on Earth for long-term astronomical observation.
), necessitating a slight modification of the usual polishing procedure. Although the outer six mirrors will individually be off-axis, the design calls for the mirrors to be arranged so that the reflecting surface of all seven mirrors as a whole is on-axis, with one mirror in the center and the other six arranged symmetrical around the center, giving a focal plane on-axis with the entire assembly. The intention is to build seven identical off-axis mirrors, so that a spare is available to substitute for a segment being recoated, a 1–2 week (per segment) process required every 1–2 years.
The mirrors are being constructed by the Steward Observatory
at the University of Arizona
, at a laboratory beneath the university's football stadium
. The casting of the first mirror, in a rotating furnace
, was completed on November 3, 2005, but the time-consuming shaping and polishing will be completed fall, 2011.
The telescope will make use of adaptive optics
.
Extremely large telescope
An extremely large telescope is an astronomical observatory featuring a telescope with an aperture of more than 20 m diameter when discussing reflecting telescopes of optical wavelengths including ultraviolet , visible, and near infrared wavelengths. Among many planned capabilities, ELTs are...
planned for completion in 2018. It will consist of seven 8.4 m (27.6 ft) diameter primary segments, with the resolving power of a 24.5 m (80.4 ft) primary mirror and collecting area equivalent to 21.4 m (70.2 ft) one. The telescope is expected to have over four times the light-gathering ability of existing instruments.
Planned site
The confirmed location of the telescope will be the Las Campanas ObservatoryLas Campanas Observatory
Las Campanas Observatory is an astronomical observatory owned and operated by the Carnegie Institution for Science It was established in 1969 and remains the primary observing site of that institution. The headquarters is located in La Serena, Chile and the observatory is in the southern Atacama...
, which is also the site of the Magellan telescopes, some 115 km (71 mi) north-northeast
Boxing the compass
Boxing the compass is the action of naming all thirty-two points of the compass in clockwise order. Such names are formed by the initials of the cardinal directions and their intermediate ordinal directions, and are very handy to refer to a heading in a general or colloquial fashion, without...
of La Serena, Chile. Much as for previous notable telescopes, the site has been chosen as the new instrument's location because of its clear weather throughout most of the year. Moreover, due to the sparsity of population centers and other favorable geographical conditions, the night sky in most of the surrounding Atacama Desert
Atacama Desert
The Atacama Desert is a plateau in South America, covering a strip of land on the Pacific coast, west of the Andes mountains. It is, according to NASA, National Geographic and many other publications, the driest desert in the world...
region is not only free from atmospheric pollution
Air pollution
Air pollution is the introduction of chemicals, particulate matter, or biological materials that cause harm or discomfort to humans or other living organisms, or cause damage to the natural environment or built environment, into the atmosphere....
, but in addition it is probably one of the places least affected by light pollution, making the area one of the best spots on Earth for long-term astronomical observation.
Design peculiarities
The telescope is unique in that it will use seven mirror segments, each 8.4 m (27.6 ft) in diameter. These segments will then be arranged to form a single optical surface. The challenge in this is that the surface of the outer six mirror segments is not radially symmetrical (i.e. they are off-axisOff-axis optical system
An off-axis optical system is an optical system in which the optical axis of the aperture is not coincident with the mechanical center of the aperture. An optical system in which the optical axis of the aperture is not coincident with the mechanical center of the aperture...
), necessitating a slight modification of the usual polishing procedure. Although the outer six mirrors will individually be off-axis, the design calls for the mirrors to be arranged so that the reflecting surface of all seven mirrors as a whole is on-axis, with one mirror in the center and the other six arranged symmetrical around the center, giving a focal plane on-axis with the entire assembly. The intention is to build seven identical off-axis mirrors, so that a spare is available to substitute for a segment being recoated, a 1–2 week (per segment) process required every 1–2 years.
The mirrors are being constructed by the Steward Observatory
Steward Observatory
The University of Arizona's Steward Observatorys main office is located on the University's campus and is closely tied to the Department of Astronomy. Established in 1916 by its first director, Andrew Ellicott Douglass, and a $60,000 bequest made by Lavinia Steward in memory of her late husband...
at the University of Arizona
University of Arizona
The University of Arizona is a land-grant and space-grant public institution of higher education and research located in Tucson, Arizona, United States. The University of Arizona was the first university in the state of Arizona, founded in 1885...
, at a laboratory beneath the university's football stadium
Arizona Stadium
Arizona Stadium is an outdoor football stadium on the campus of the University of Arizona in Tucson, Arizona, United States. It is the home field of the Arizona Wildcats of the Pacific-12 Conference, and its current seating capacity is 57,803....
. The casting of the first mirror, in a rotating furnace
Rotating furnace
A rotating furnace is a device used to create lenses or primary mirrors for optical telescopes. It was known already to Newton that the centrifugal-force-induced shape of a spinning liquid is a paraboloid, the same as the shape of a telescope's primary focusing mirror...
, was completed on November 3, 2005, but the time-consuming shaping and polishing will be completed fall, 2011.
The telescope will make use of adaptive optics
Adaptive optics
Adaptive optics is a technology used to improve the performance of optical systems by reducing the effect of wavefront distortions. It is used in astronomical telescopes and laser communication systems to remove the effects of atmospheric distortion, and in retinal imaging systems to reduce the...
.
Organizations
The following is a list of the members of a consortium developing the telescope.- Observatories of the Carnegie Institution of Washington (OCIW)
- University of ChicagoUniversity of ChicagoThe University of Chicago is a private research university in Chicago, Illinois, USA. It was founded by the American Baptist Education Society with a donation from oil magnate and philanthropist John D. Rockefeller and incorporated in 1890...
- Harvard UniversityHarvard UniversityHarvard University is a private Ivy League university located in Cambridge, Massachusetts, United States, established in 1636 by the Massachusetts legislature. Harvard is the oldest institution of higher learning in the United States and the first corporation chartered in the country...
- Smithsonian Astrophysical ObservatorySmithsonian Astrophysical ObservatoryThe Smithsonian Astrophysical Observatory is a research institute of the Smithsonian Institution headquartered in Cambridge, Massachusetts, where it is joined with the Harvard College Observatory to form the Harvard-Smithsonian Center for Astrophysics .-History:The SAO was founded in 1890 by...
- Texas A&M UniversityTexas A&M UniversityTexas A&M University is a coeducational public research university located in College Station, Texas . It is the flagship institution of the Texas A&M University System. The sixth-largest university in the United States, A&M's enrollment for Fall 2011 was over 50,000 for the first time in school...
- University of ArizonaUniversity of ArizonaThe University of Arizona is a land-grant and space-grant public institution of higher education and research located in Tucson, Arizona, United States. The University of Arizona was the first university in the state of Arizona, founded in 1885...
- University of Texas at AustinUniversity of Texas at AustinThe University of Texas at Austin is a state research university located in Austin, Texas, USA, and is the flagship institution of the The University of Texas System. Founded in 1883, its campus is located approximately from the Texas State Capitol in Austin...
- Australian National UniversityAustralian National UniversityThe Australian National University is a teaching and research university located in the Australian capital, Canberra.As of 2009, the ANU employs 3,945 administrative staff who teach approximately 10,000 undergraduates, and 7,500 postgraduate students...
- Astronomy Australia LimitedAstronomy Australia LimitedThe Astronomy Australia Limited is a not-for-profit company whose members are a range of Australian universities and research organisations. Its core purpose is to manage programmes which provide astronomers with access to national optical/infrared and radio astronomy infrastructure.The...
- Korea Astronomy and Space Science InstituteKorea Astronomy and Space Science InstituteThe Korea Astronomy and Space Science Institute is the astronomy and space science agency of South Korea. Its headquarters are located in Daejeon, in the Daedeok Science Town.- See also :* Bohyunsan Optical Astronomy Observatory...
See also
- La Serena, Chile
- Magellan telescopesMagellan telescopesThe Magellan Telescopes are a pair of 6.5 m diameter optical telescopes located at Las Campanas Observatory in Chile. The two telescopes are named after the astronomer Walter Baade and the philanthropist Landon T...
- Atacama DesertAtacama DesertThe Atacama Desert is a plateau in South America, covering a strip of land on the Pacific coast, west of the Andes mountains. It is, according to NASA, National Geographic and many other publications, the driest desert in the world...
- Las Campanas ObservatoryLas Campanas ObservatoryLas Campanas Observatory is an astronomical observatory owned and operated by the Carnegie Institution for Science It was established in 1969 and remains the primary observing site of that institution. The headquarters is located in La Serena, Chile and the observatory is in the southern Atacama...
- Extremely Large TelescopeExtremely Large TelescopeThe European Extremely Large Telescope is a ground-based extremely large telescope featuring an optical/near-infrared telescope of large size and advanced features that is being planned by the European Southern Observatory...
- List of largest optical reflecting telescopes
- Gran Telescopio CanariasGran Telescopio CanariasThe Gran Telescopio Canarias , also known as GranTeCan or GTC, is a reflecting telescope undertaking commissioning observations at the Roque de los Muchachos Observatory on the island of La Palma, in the Canary Islands of Spain, as of July 2009.Construction of the telescope, sited on a volcanic...
External links
- Giant Magellan Telescope home page
- Article from the MIT news office
- New Scientist article on the telescope
- COSMOS article on the telescope
- Painted outline of the mirrors at the parking lot of the Observatories of the Carnegie Institution in PasadenaPasadena, CaliforniaPasadena is a city in Los Angeles County, California, United States. Although famous for hosting the annual Rose Bowl football game and Tournament of Roses Parade, Pasadena is the home to many scientific and cultural institutions, including the California Institute of Technology , the Jet...