With a primary mirror diameter of 25.4 meters, it is expected to be the largest Gregorian telescope ever built, observing in optical and mid-infrared wavelengths (320–25,000 nm).

The GMT will be used to explore a wide range of astrophysical phenomena, including the search for signs of life on exoplanets and the study of the cosmic origins of chemical elements.

[12][13][14] The project, with an estimated cost of USD $2 billion, is being developed by the GMTO Corporation, a consortium of research institutions from seven countries: Australia, Brazil, Chile, Israel, South Korea, Taiwan, and the United States.

[19] The sparse population in the surrounding Atacama Desert, combined with favorable geographical conditions, ensures minimal atmospheric and light pollution.

This structure will float on a film of oil (50 microns thick), being supported by a number of hydrostatic bearings to allow the telescope mount to glide frictionlessly in three degrees of freedom.

[33] In October 2019, GMTO Corporation announced the signing of a contract with German company MT Mechatronics (subsidiary of OHB SE) and Illinois-based Ingersoll Machine Tools, to design, build and install the Giant Magellan Telescope’s structure.

Ingersoll Machine Tools finished constructing a 40,000 square foot facility to manufacture the Giant Magellan Telescope mount in Rockford, Illinois in December 2021.

It also makes the telescope extremely stiff and stable so that it can resist image quality interruptions from wind and mechanical vibrations.

[35] As a precursor to the fabrication of the seven mirror support systems, a full-scale prototype has also been built to validate design decisions and demonstrate the performance.

The challenge is that the outer six mirror segments will be off-axis, and although identical to each other, will not be individually radially symmetrical, necessitating a modification of the usual polishing and testing procedures.

[13] Each takes approximately 4 years to cast and polish, obtaining a finish that is so smooth that the highest peaks and valleys are smaller than 1/1000 of the width of a human hair.

The images will be sharp enough to resolve the torch engraved on a U.S. dime from nearly 160 kilometers (100 miles) away and expected to exceed that of the Hubble Space Telescope.

[43] The Carnegie Observatories office in Pasadena has an outline of the Giant Magellan primary mirror array painted in its parking lot.

The Adaptive Secondary Mirrors consist of a thin sheet of glass that is bonded to more than 7000 independently controlled voice coil actuators.

Using this system, it is possible to observe multiple targets over the entire field with one or more of the spectrographs This enables the telescope to see fainter objects with unrivaled resolution and sensitivity.

The advantage is extremely powerful for spectroscopy and the precise measurements of distances, dynamics, chemistry, and masses of celestial objects in deep space.

[51] Science drivers for the Giant Magellan Telescope include studying planets in the habitable zones of their parent star in the search for life; the nature of dark matter, dark energy, gravity, and many other aspects of fundamental physics; the formation and evolution of the first stars and galaxies; and how black holes and galaxies co-evolve.

[54] The Giant Magellan Telescope is the work of the GMTO Corporation, an international consortium of research institutions representing seven countries from Australia, Brazil, Chile, Israel, South Korea, Taiwan, and the United States.

The telescope operates under a cooperative agreement with the University of Chile, granting 10% of the observing time to astronomers working at Chilean institutions.