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Extremely Large Telescope

Coordinates: 24°35′21″S 70°11′30″W / 24.5893°S 70.1916°W / -24.5893; -70.1916
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European Extremely Large Telescope (E-ELT)
Image Credit: ESO
Image Credit: ESO
Artist's impression of the E-ELT design
Alternative namesELT Edit this at Wikidata
Location(s)Cerro Armazones, Antofagasta Province, Antofagasta Region, Chile
Coordinates24°35′21″S 70°11′30″W / 24.5893°S 70.1916°W / -24.5893; -70.1916 Edit this at Wikidata
OrganizationESO
WavelengthOptical, near infrared
BuiltPlanned completion: 2018
Telescope styleReflector
Diameter42 m (138 ft)
Secondary diameter4.09 m (13 ft 5 in) Edit this at Wikidata
Tertiary diameter3.75 m (12 ft 4 in) Edit this at Wikidata
Angular resolution0.001 to 0.6 arcseconds depending on target and instruments used
Focal length420-840 m (f/10 - f/20)
MountingAlt/az
EnclosureSpherical
Websitehttp://www.eso.org/public/astronomy/projects/e-elt.html
Extremely Large Telescope is located in Chile
Extremely Large Telescope
Location of European Extremely Large Telescope (E-ELT)
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The European Extremely Large Telescope (E-ELT) is an extremely large telescope design proposed for the next-generation European Southern Observatory optical telescope with a diameter aperture of 42 metres (138 feet) with a filled aperture mirror with an area of 1,300 m² [1].

Goals and planning

The ESO is focusing on this design after a feasibility study concluded the proposed 100 metres (330 ft) diameter Overwhelmingly Large Telescope would cost €1.5 billion (£1 billion), and be too complex. Current fabrication technology limits single mirrors to being roughly 8 metres (26 ft) in a single piece. The next-largest telescopes currently in use are the Gran Telescopio Canarias and Southern African Large Telescope, which each use hexagonal mirrors fitted together to make a mirror more than 10 metres (33 ft) across. The E-ELT would need to use a similar design. In addition, the E-ELT would also need to use techniques to work around atmospheric distortion of incoming light, known as adaptive optics (AO).

Project E-ELT has the aim of observing the Universe in greater detail than even the Hubble Space Telescope. A mirror of approximately 42 metres (138 feet) would allow the study of the atmospheres of extrasolar planets. The E-ELT is now planned in the Astronet Infrastructure Roadmap, and “is currently going through a Phase B study that will end with a Final Design Review of the whole facility in 2009/2010. This Phase B study includes contracts with industry to design and manufacture prototypes of key elements like the primary mirror segments, the adaptive fourth mirror or the mechanical structure. It also includes concept studies for eight instruments.”[2]

Because of the competition with some similar projects (in particular the Thirty Meter Telescope and the Giant Magellan Telescope), “the decision for the construction of the European ELT cannot be deferred later than 2010.”[3] The construction period is estimated to be 5-6 years leading to first light around 2016. The design phase of the 5-mirror anastigmat (€57M) is fully funded within the ESO budget, and the construction cost is estimated to be €960M (including first generation instruments). “About €350M for the construction phase are available within the existing budget integrated over a period of ten years. One of the goals of the preparatory phase is to study the possibilities for additional funding. Additional activities on the organisation of the project and the mission design are supported through a €5M FP7 grant.”[4]

Instrumentation

Model of the gigantic and intricate structure inside the enclosure of the E-ELT.

Eight different instrument concepts and two post-focal AO modules are currently being studied, with the aim that two to three will be ready for first light, with the others becoming available at various points over the following decade.[5] The instruments being studied are:

  • CODEX: a very high resolution optical spectrograph[6]
  • EAGLE: a wide-field, multiple integral field unit near-infrared (NIR) spectrograph, with multi-object adaptive optics[7]
  • EPICS: a optical/NIR planet imager and spectrograph with extreme AO[8]
  • HARMONI: a single field, wide-band spectrograph
  • METIS: a mid-infrared imager and spectrograph
  • MICADO: a diffraction-limited near-infrared camera
  • OPTIMOS: a wide-field visual multi-object spectrograph
  • SIMPLE: a high spectral resolution NIR spectrograph

The two post-focal AO modules currently being studied are:

Location

Cerro Armazones

Sites that were under discussion include Cerro Macon, Salta, in Argentina; Roque de los Muchachos Observatory, on the Canary Islands; and sites in South Africa, Morocco, and Antarctica.

See also

References

  1. ^ http://www.eso.org/public/astronomy/teles-instr/e-elt_num.html
  2. ^ Astronet, 2008, The astronet Infrastructure Roadmap: A Strategic Plan for European Astronomy, p. 43
  3. ^ Astronet, 2008, The astronet Infrastructure Roadmap: A Strategic Plan for European Astronomy, p. 43
  4. ^ Astronet, 2008, The astronet Infrastructure Roadmap: A Strategic Plan for European Astronomy, p. 43
  5. ^ "E-ELT Instrumentation". Retrieved 2009-10-29.
  6. ^ Pasquini, Luca (2008). "CODEX: the high-resolution visual spectrograph for the E-ELT" (PDF). SPIE. doi:10.1117/12.787936. {{cite journal}}: Cite journal requires |journal= (help); Unknown parameter |booktitle= ignored (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
  7. ^ "EAGLE: the Extremely Large Telescope Adaptive Optics for Galaxy Evolution instrument". Retrieved 2009-10-29.
  8. ^ Kasper, Markus E. (2008). "EPICS: the exoplanet imager for the E-ELT". Adaptive Optics Systems - Proceedings of the SPIE, Volume 7015. SPIE. pp. 70151S-70151S-12. doi:10.1117/12.789047. {{cite conference}}: Unknown parameter |booktitle= ignored (|book-title= suggested) (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
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