large-binocular-telescope-lbt Large Binocular Telescope (LBT) Q845304 11.9 Multiple Two 8.4 m (331 in) mirrors USA, Italy, Germany Mount Graham International Observatory, Arizona, USA 2005 gran-telescopio-canarias-gtc Gran Telescopio Canarias (GTC) Q59973 10.4 Segmented 36 hexagonal segments Spain, Mexico, USA Roque de los Muchachos Obs., Canary Islands, Spain 2006 hobby-eberly-telescope-het Hobby–Eberly Telescope (HET) Q139605 10 Segmented 91 × 1 m (39 in) hexagonal segments forming an 11 m × 9.8 m mirror USA, Germany McDonald Observatory, Texas, USA 1997 Aperture increased 2015 keck-1 Keck 1 Q210997 10 Segmented 36 hexagonal segments USA Mauna Kea Observatories, Hawaii, USA 1993 keck-2 Keck 2 Q210997 10 Segmented 36 hexagonal segments USA Mauna Kea Observatories, Hawaii, USA 1996 southern-african-large-telescope-salt Southern African Large Telescope (SALT) Q833639 9.2 Segmented 91 × 1 m (39 in) hexagonal segments forming an 11 m × 9.8 m mirror South Africa, USA, UK, Germany, Poland, New Zealand South African Astronomical Obs., Northern Cape, South Africa 2005 subaru-jnlt Subaru (JNLT) Q841079 8.2 Single Japan Mauna Kea Observatories, Hawaii, USA 1999 vlt-ut1-antu VLT UT1 – Antu Q265628 8.2 Single ESO Countries, Chile Paranal Observatory, Antofagasta Region, Chile 1998 vlt-ut2-kueyen VLT UT2 – Kueyen Q265628 8.2 Single ESO Countries, Chile Paranal Observatory, Antofagasta Region, Chile 1999 vlt-ut3-melipal VLT UT3 – Melipal Q265628 8.2 Single ESO Countries, Chile Paranal Observatory, Antofagasta Region, Chile 2000 vlt-ut4-yepun VLT UT4 – Yepun Q265628 8.2 Single ESO Countries, Chile Paranal Observatory, Antofagasta Region, Chile 2001 gemini-north-gillett Gemini North (Gillett) Q744667 8.1 Single USA, UK, Canada, Chile, Australia, Argentina, Brazil Mauna Kea Observatories, Hawaii, USA 1999 gemini-south Gemini South Q744667 8.1 Single USA, UK, Canada, Chile, Australia, Argentina, Brazil Cerro Pachón (CTIO), Coquimbo Region, Chile 2001 james-webb-space-telescope James Webb Space Telescope Q186447 6.5 Segmented 18 hexagonal segments NASA, ESA, CSA Halo orbit around the Earth-Sun L2 Point 2022 mmt-current-optics MMT (current optics) Q779895 6.5 Single USA F. L. Whipple Obs., Arizona, USA 2000 magellan-1-walter-baade Magellan 1 (Walter Baade) Q1541020 6.5 Single USA Las Campanas Obs., Atacama Region, Chile 2000 magellan-2-landon-clay Magellan 2 (Landon Clay) Q1541020 6.5 Single USA Las Campanas Obs., Atacama Region, Chile 2002 tokyo-atacama-observatory-tao Tokyo Atacama Observatory (TAO) Q652811 6.5 Single Japan Cerro Chajnantor, Atacama Desert, Chile 2024 simonyi-survey-telescope Simonyi Survey Telescope Q672021 6.4 Combined primary & tertiary mirror Total diameter 8.4 m (331 in) USA Vera C. Rubin Observatory, Coquimbo Region, Chile 2025 bta-6 BTA-6 Q787671 6 Single USSR/Russia Special Astrophysical Obs., Karachay–Cherkessia, Russia 1975 large-zenith-telescope-lzt Large Zenith Telescope (LZT) Q1805929 6 Liquid Canada, France, United States Maple Ridge, British Columbia, Canada 2003 Decommissioned 2016 hale-telescope Hale Telescope Q2471197 5.08 Single USA Palomar Observatory, California, USA 1949 lamost LAMOST Q1513326 4.9 Segmented 37 segments for the 6.67 m × 6.05 m primary and 24 segments for the 5.72 m × 4.40 m corrector; effective aperture 3.6–4.9 m China Beijing Astronomical Obs., Xinglong, China 2008 mmt-original-optics-see-above-for-current-version MMT (original optics) (see above for current version) Q779895 4.7 Multiple Six 1.8 m (71 in) mirrors USA F. L. Whipple Obs., Arizona, USA 1979 Mirrors removed 1998 lowell-discovery-telescope Lowell Discovery Telescope Q1383460 4.3 Single USA Lowell Observatory, Happy Jack, Arizona, USA 2012 william-herschel-telescope William Herschel Telescope Q541505 4.2 Single UK, Netherlands, Spain Roque de los Muchachos Obs., Canary Islands, Spain 1987 soar SOAR Q787525 4.1 Single USA, Brazil Cerro Pachón (CTIO), Coquimbo Region, Chile 2002 vista VISTA Q612291 4.1 Single ESO Countries, Chile Paranal Observatory, Antofagasta Region, Chile 2009 victor-m-blanco-telescope Víctor M. Blanco Telescope Q7944666 4 Single USA Cerro Tololo Inter-American Obs., Coquimbo Region, Chile 1976 international-liquid-mirror-telescope International Liquid Mirror Telescope Q112861106 4 Liquid Belgium, Canada, India, Poland ARIES Devasthal Observatory, Nainital, India 2022 nicholas-u-mayall-4-m Nicholas U. Mayall 4 m Q3546489 4 Single USA Kitt Peak National Obs., Arizona, USA 1973 daniel-k-inouye-solar-telescope Daniel K. Inouye Solar Telescope Q2825377 4 Single USA Haleakala Observatory, Hawaii, USA 2019 dag-telescope DAG Telescope Q6032929 4 Single Turkey Eastern Anatolia Observatory, Erzurum, Turkey 2025 anglo-australian-telescope-aat Anglo-Australian Telescope (AAT) Q2632045 3.89 Single Australia, UK Australian Astronomical Obs., New South Wales, Australia 1974 united-kingdom-infrared-telescope-ukirt United Kingdom Infrared Telescope (UKIRT) Q848021 3.8 Single UK, United States Mauna Kea Observatories, Hawaii, USA 1979 3-67-m-aeos-telescope-aeos 3.67 m AEOS Telescope (AEOS) Q4634267 3.67 Single USA Air Force Maui Optical Station, Hawaii, USA 1996 3-6-m-devasthal-optical-telescope-dot 3.6 m Devasthal Optical Telescope (DOT) Q24949537 3.6 Single India ARIES Devasthal Observatory, Nainital, India 2016 telescopio-nazionale-galileo-tng Telescopio Nazionale Galileo (TNG) Q16269 3.58 Single Italy Roque de los Muchachos Obs., Canary Islands, Spain 1997 new-technology-telescope-ntt New Technology Telescope (NTT) Q1982969 3.58 Single ESO countries La Silla Observatory, Coquimbo Region, Chile 1989 canada-france-hawaii-telescope-cfht Canada-France-Hawaii Telescope (CFHT) Q1031946 3.58 Single Canada, France, USA Mauna Kea Observatories, Hawaii, USA 1979 eso-3-6-m-telescope ESO 3.6 m Telescope Q74784 3.57 Single ESO countries La Silla Observatory, Coquimbo Region, Chile 1977 mpi-caha-3-5-m MPI-CAHA 3.5 m Q209610 3.5 Single West Germany, Spain Calar Alto Obs., Almería, Spain 1984 usaf-starfire-3-5-m USAF Starfire 3.5 m Q2332743 3.5 Single USA Starfire Optical Range, New Mexico, USA 1994 wiyn-telescope WIYN Telescope Q7951025 3.5 Single USA Kitt Peak National Obs., Arizona, USA 1994 space-surveillance-telescope Space Surveillance Telescope Q1418160 3.5 Single USA, Australia White Sands Missile Range, New Mexico, United States Relocated to Harold E. Holt Naval Communication Station, Western Australia, Australia 2011 Relocated 2020 astrophysical-research-consortium-arc Astrophysical Research Consortium (ARC) Q616529 3.48 Single USA Apache Point Obs., New Mexico, USA 1994 iranian-national-observatory-ino340 Iranian National Observatory (INO340) Q5931793 3.4 Single Iran Mount Gargash, Isfahan Province, Iran 2022 shane-telescope Shane Telescope Q5006395 3.05 Single USA Lick Observatory, California, USA 1959 nasa-infrared-telescope-facility NASA Infrared Telescope Facility Q1662664 3 Single USA Mauna Kea Observatory, Hawaii, USA 1979 nasa-lmt NASA-LMT Q126192277 3 Liquid USA NASA Orbital Debris Obs., New Mexico, USA 1995 Decommissioned 2002