extremely large telescope
(optical telescope with a 20+ meter aperture)
Extremely large telescope (ELT) is a general
term for a very large telescope,
commonly using 20 meters as a defining minimum aperture.
As of 2017, some are funded and under construction
but none complete and the largest current telescopes have apertures of
about 10 meters.
A typical ELT design is to use a segmented mirror with adaptive optics.
Current plans and construction:
- Giant Magellan Telescope (GMT) - 24.5m, under construction, at Las Campanas, Chile.
- European Extremely Large Telescope (E-ELT) - 39.3m, under construction, at, Cerro Armazones, Chile.
- Thirty Meter Telescope (TMT) - 30m, planned, for Mauna Kea, Hawaii.
The E-ELT has taken the name the Extremely Large Telescope
or the ELT.
European Extremely Large Telescope (E-ELT)
Giant Magellan Telescope (GMT)
Giant Segmented Mirror Telescope (GSMT)
Thirty Meter Telescope (TMT)