extremely large telescopes include the Extremely Large Telescope and the Thirty Meter Telescope. Organizations The project is US-led in partnership with Australia, Brazil, and South Korea, with Chile as the host country. The following organizations are members of the consortium developing the telescope. University of Arizona (Department of Astronomy and Steward Observatory) Arizona State University (School of Earth and Space Exploration (SESE)) Astronomy Australia Limited Australian National University (Research School of Astronomy and Astrophysics) Carnegie Observatories University of São Paulo (São Paulo Research Foundation – FAPESP) Harvard University (jointly; Center for Astrophysics Harvard & Smithsonian (CfA)) Korea Astronomy and Space Science Institute (한국천문연구원) (KASI) Smithsonian Institution (jointly; Center for Astrophysics Harvard & Smithsonian (CfA)) Texas A&M University University of Texas at Austin (Department of Astronomy at the University of Texas at Austin) University of Chicago (Astronomy & Astrophysics Department of the University of Chicago) The Carnegie Observatories office in Pasadena has an outline of the GMT primary mirror array painted in its parking lot. It is easily visible in satellite imagery at . In January 2018, WSP was awarded the contract to manage construction of the GMT. Status of mirrors There will be a total of eight primary mirror segments: one central mirror, six off-axis segments, and a spare off-axis segment which will be rotated into use as each segment is cleaned and recoated. The mirrors are made of borosilicate glass and have a honeycomb structure below the mirror surface. An adaptive secondary mirror is also designed for the telescope. The telescope will begin observing with only four mirrors: the central and three off-axis segments. Mirror 1, cast in October 2005, completed in August 2012 with polishing completed with a surface accuracy of 19 nanometers RMS. Mirror 2, cast in January 2012, completed in 2019. Mirror 3, cast in August 2013, currently (August 2022) receiving the final touches on its polishing and is in final testing. Mirror 4, cast in September 2015. This is the central mirror. Currently (March 2021) the rear surface is polished and is having its load spreaders installed. Mirror 5, cast in November 2017. Mirror 6, cast in March 2021. Approximated to take 4 years to complete. Mirror 7, in planning, will be cast in 2023. Mirror 8, planned. The secondary mirror, which is a deformable mirror tasked with correcting the atmospheric distortion of the light gathered by the telescope, has 7 segments and 1.1 meter