The Giant Magellan Telescope

GMT at Twilight (GMTO Corporation)

An artist's conception of the Giant Magellan Telescope at twilight. Note the truck at the lower right for scale. Image copyright Giant Magellan Telescope - GMTO Corporation.

The Giant Magellan Telescope is a collaboration between the Carnegie Institution for Science, Harvard University, the Smithsonian Astrophysical Observatory, Texas A&M University, the Korea Astronomy and Space Science Institute, the University of Texas at Austin, the Australian National University, the University of Arizona, Astronomy Australia Ltd. and the University of Chicago. GMT should be completed around 2018.

The Telescope

The primary mirror of GMT will be composed of seven circular segments 8.4m in diameter arranged as shown in the figure below. In order to properly focus the light, the outer six segments are shaped asymmetrically like potato chips. The resolving power of GMT will be equivalent to the resolving power of a 24.5 meter telescope. The secondary mirror (also pictured below) consists of an adaptive shell for each of the primary mirror segments and will be controlled by the adaptive optics system to correct for atmospheric turbulence over a field of view 10′-20′ in diameter.

Artist's conception of GMT primary mirror (Giant Magellan Telescope - GMTO Corporation)

An artist's conception of the primary and secondary mirrors of GMT. Image copyright Giant Magellan Telescope - GMTO Corporation.

The Site

The chosen site for GMT is Cerro Las Campanas in Chile. Cerro Las Campanas, pictured below, is located at an altitude of >2550 meters and has dry weather, dark skies, and good seeing. For more information about the site, see the GMT site selection page.

GMT on Cerro Las Campanas (GMTO Corporation)

An artist's conception of GMT on the peak of Cerro Las Campanas in Chile. Image from GMTO Corporation.


GMT’s instruments will be placed behind the central primary mirror. There will be a large (6m x 5m) space directly behind the mirror for large instruments and a rotating platform for smaller instruments. See the technical overview page for more information about instrument mounting.

The proposed first generation instruments for GMT are shown in the table below from the GMT Progress Report SPIE Conf. 7012-46. According to the report, three instruments will be selected for first light.

GMT Instrument Concepts (Progress on the GMT, Johns)

GMT Instrument Concepts. (Table 6 from SPIE 7012-46, Progress on the GMT by Matt Johns at Carnegie Observatories)

Science Goals

The science goals that will be addressed by GMT include:

  • Detection and characterization of exoplanets
  • Study of dark matter and dark energy
  • Observations of stellar populations and the origin of elements
  • Observations of black hole growth
  • Study of galaxy formation
  • Observations of the epoch of reionization
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