List of largest optical telescopes in the 20th century
Introduction ''The 60 inch telescope, first light in 1908''The following is a '''list of the largest optical telescopes in the 20th century''', paying special attention to the diameter of the mirror or lens of the telescope's objective, or aperture. Aperture rank currently goes approximately by the usable physical aperture size and not by aperture synthesis, although interferometers attained some of the highest angular resolutions at visible and infrared wavelengths compared to traditional telescopes. Diverging methods of construction and use for reflecting telescopes in that area make comparing synthesized aperture irregular.For instance, Keck I or II alone has less angular resolution than the Keck Interferometer (Keck I & II together), however, the Keck Interferometer is used for a much narrower range of type of observations. Ultimately, a valid comparison between two telescopes must take into consideration more specifications, when a general measurement becomes obtuse.Aperture of the primary mirror alone can be poor measure of a reflective telescope's significance; for example, the Hubble Space Telescope has only a  primary mirror. In addition, many large or significant telescopes are not optical and/or reflecting. However, many famous optical telescopes have had large apertures on their primary mirror with corresponding good angular resolution.The list Includes optical observatories, including UV, visible and some optical infrared telescopes, and near infrared. The list covers from about 1901 to 2001, with some flexibility to accommodate ambiguity in classification, for example some 2002 telescopes, if it was nearly operation in 2001.19th century and earlier telescopes that ceased operation are not included, but the list is not complete.
Table of optical telescopes Multiple mirror telescopes are ranked by their equivalent optical area, not peak interferometric aperture unless it is not relevant for the design. See also List of astronomical interferometers at visible and infrared wavelengths.See also List of largest optical refracting telescopes, as this list does yet not include such large refractors as the Yerkes Observatory. Name/Observatory  Aperture m Aper. in  Mirror type   Nationality of Sponsors  Site and/or Observatory  FL or Built  Image  Keck 1  10 m  394″ Segmented,36 United States  Mauna Kea Observatory, Hawaii  1993  50px Keck 2  10 m  394″ Segmented,36 United States  Mauna Kea Observatory, Hawaii  1996  50px Hobby-Eberly Telescope (HET)  9.2 m  362″ Segmented,91 United States, Germany  McDonald Observatory, Texas  1997  50px Subaru (JNLT)  8.2 m  323″ Single  Japan  Mauna Kea Observatory, Hawaii  1999  50px VLT 1 (Antu)  8.2 m  323″ Single  ESO Countries + Chile  Paranal Observatory, Chile  1998  50px VLT 2 (Kueyen)  8.2 m  323″ Single  ESO Countries + Chile  Paranal Observatory, Chile  1999 VLT 3 (Melipal)  8.2 m  323″ Single  ESO Countries + Chile  Paranal Observatory, Chile  2000* VLT 4 (Yepun)  8.2 m  323″ Single  ESO Countries + Chile  Paranal Observatory, Chile  2001* Gemini North (Gillett) 8.1 m  318″ Single  United States, Canada, Chile, Australia, Argentina, Brazil  Mauna Kea Obs., Hawaii  1999  50px Gemini South  8.1 m  318″ Single  United States, Canada, Chile, Australia, Argentina, Brazil  Cerro Pachón, Chile  2001 MMT  6.5 m  256″ Single United States  F. L. Whipple Obs., Arizona  2000 Magellan 1 (Walter Baade)  6.5 m  256″ Honeycomb  United States  Las Campanas Obs., Chile  2000  50px Magellan 2 (Landon Clay)  6.5 m  256″ Honeycomb  United States  Las Campanas Obs., Chile  2002*  BTA-6  6 m  238″ Single USSR + Russia  Zelenchukskaya, Caucasus  1976 Hale Telescope (200 inch)  5.08 m  200″  Single  United States  Palomar Observatory, California  1948  50px MMT (original) (6 x 1.8 m) ''optics replaced''  4.7 m (6 x 1.8 m)  186″ 6 mirrors  United States F. L. Whipple Obs., Arizona  1979–1998 William Herschel Telescope  4.2 m  165″ Single  UK, Netherlands, Spain  ORM, Canary Islands  1987  50px SOAR  4.1 m  161″ Single  United States, Brazil  Cerro Pachón, Chile  2002*  50px Nicholas U. Mayall 4m  4 m  158″ Single  USA  Kitt Peak National Obs. ; Arizona  1973  50px Victor M. Blanco Telescope  4 m  158″ Single  USA  Cerro Tololo Inter-American Obs., Chile 1976  50px Anglo-Australian Telescope (AAT)  3.89 m  154″ Single  United Kingdom + Australia Anglo-Australian Obs. ; Siding Spring, Australia  1975  50px United Kingdom Infrared Telescope (UKIRT)  3.8 m  150″ Single IR  United Kingdom  Mauna Kea Observatories; Mauna Kea, Hawaii  1978 3.67m AEOS Telescope (AEOS)  3.67 m  145″  Single  United States  Air Force Maui Optical Station; Haleakala, Hawaii  1996 Telescopio Nazionale Galileo (TNG) 3.58 m  138″ Single  Italy   ORM; La Palma, Canary Islands  1997  50px New Technology Telescope (NTT)3.58 m  142″ Single  ESO countries European Southern Observatory; Cerro La Silla, Chile  1989  50px Canada-France-Hawaii Telescope (CFHT) 3.58 m 141″  Single  Canada, France, United States  Mauna Kea Observatories, USA  1979  50pxESO 3.6 m Telescope 3.57 m  140″ Single  ESO countries  European Southern Observatory; Cerro La Silla, Chile  1977  50px MPI-CAHA 3.5m  3.5 m  138″ Single  West Germany+Spain  Calar Alto Obs., Spain  1984 USAF Starfire 3.5m 3.5 m  138″ Single  USA  Starfire Optical Range; New Mexico  1994  50pxWIYN Telescope3.5 m 138″ Single  USA  Kitt Peak National Obs., USA  1994  50px  Astrophysical Research Consortium (ARC)  3.48 m  137″ Single  USA  Apache Point Obs. ; Sacramento Peak, New Mexico  1994 Shane Telescope  3.05 m  120″ Single  United States Lick Observatory; Mt. Hamilton, California  1959  50px Infrared Telescope Facility (IRTF)  3 m  118″ Single IR  United States   Mauna Kea, Hawaii  1979 NASA-LMT (NODO) ''retired''  3 m  118″  Liquid  USA  Sacramento Peak, New Mexico, USA  1995–2002 Harlan J. Smith Telescope  2.72 m  107″ Single  USA  McDonald Observatory, Texas, USA  1969-  50px UBC-Laval LMT  2.65 m  104″ Liquid Canada  Vancouver, Canada  1992– Shajn 2.6m (Crimean 102 in) 2.64 m  103″  Single    Crimean Astrophysical Obs., Ukraine  1961 BAO 2.6  2.6 m  102″ Single    Byurakan Astrophysical Obs. ; Mt. Aragatz, Armenia  1976 Nordic Optical Telescope (NOT) 2.56 m 101″  Single  Denmark, Sweden, Iceland, Norway, Finland La Palma, Canary Islands  1988  50px Isaac Newton Telescope (INT) 2.54 m  100″  Zerodur   UK   La Palma, Canary Islands ''moved/new mirror''  1984  50px du Pont  2.54 m  100″  Single  USA  Las Campanas Observatory, Chile 1976 Hooker 100-Inch Telescope  2.54 m 100″  Single  United States  Mt. Wilson Observatory; California  1917 Sloan DSS  2.5 m 98″  Single  United States   Sacramento Peak, New Mexico  1997 Isaac Newton Telescope (INT)  2.54 m  98″  Single   UK  RGO, Sussex, England ''(original)''  1965–1979 Hiltner Telescope  2.4 m 95″  Single  United States  MDM Observatory, Kitt Peak, Arizona  1986Hubble (HST)   2.4 m 94″ Single  NASA+ESA  Low Earth orbit  1990 Vainu Bappu  2.34 m  92″   Single    Vainu Bappu Observatory, India  1986 WIRO 2.3  2.3 m  90.5″ Single  USA  Wyoming, USA   1977 ANU 2.3m ATT  2.3 m  90″  Single  Australia  Siding Spring Obs., Australia  1984Bok Telescope (90-inch)  2.3 m  90″  Single  USA  Steward Obs., Kitt Peak, Arizona  1969 University of Hawaii 2.2 m  2.24 m  88″  Single  USA  Mauna Kea Observatories, Hawaii  1970 MPIA-ESO (ESO-MPI) 2.2 m  87″  Single  West Germany  Cerro La Silla, Chile   1984 MPIA-CAHA 2.2m 2.2 m  87″  Single  West Germany  Calar Alto Observatory, Spain  1979  Xinglong 2.16m  2.16 m  85″  Single  PRC (China)  Xinglong, China  1989Jorge Sahade 2.15m  2.15 m  84″  Single     Leoncito Astronomical Complex, Argentina   1987  INAOE 2.12 (OAGH)  2.12 m  83″   Single  Mexico, USA  Guillermo Haro Observatory; Sonora   1987  UNAM 2.12   2.12 m  83"  Single   NAO; San Pedro, Mexico  1979 Kitt Peak 2.1-meter  2.1 m  83″  Single  USA  Kitt Peak (KNPO), USA  1964 Otto Struve Telescope  2.1 m  82  Single  USA  McDonald Observatory, USA  1939 Himalayan Chandra Telescope (HCT) 2.01 m 79″ Single  India   Indian Astronomical Obs., Hanle (4500 m) 2000 Alfred Jensch Teleskop  2 m 79″ Single    Karl Schwarzschild Observatory  1960 Carl Zeiss Jena  2 m 79″ Single     Shamakhi Astrophysical Obs., Azerbaijan  1966 Ondřejov 2-m   2 m 79″ Single  Czechoslovakia   Ondřejov Observatory, Czechia  1967  50px Ritchey-Chretien-Coude (RCC)  2 m 79″ Single    Rozhen Observatory, Bulgaria  1984 Carl Zeiss Jena  2 m 79″ Single    Main Ukraine Obs. Bernard Lyot Telescope  2 m  79″ Single  France   Pic du Midi Obs., France  1980  50pxFaulkes Telescope South  2 m  79″ Single  UK Siding Spring Obs., Australia 2001  50px MAGNUM  2 m  79″ Single IR  Japan Haleakala Obs., USA  2001 OHP 1.93  1.93 m  76″ Single   France   Haute-Provence Observatory, France  1958 74 inch Radcliffe Telescope (1.9 m) 1.88 m  74″  Single    South African Astronomical Obs., Sutherland, 1974–PresentRadcliffe Obs.,1948– 1974 1950 188 cm telescope  1.88 m  74″  Single  Japan Okayama Astrophysical Observatory, Japan 1960 DDO 1.88 m  1.88 m  74″  Single  Canada  David Dunlap Observatory, Ontario  1935 74" reflector  1.88 m  74″  Single  Australia Mount Stromlo Observatory, Australia 1955–2003 Kottamia telescope 1.88 m 1.88 m  74″  Single  Egypt   Egypt  1960 Vatican Advanced Technology Telescope (VATT)  1.83 m  72″  Single  Vatican City   Mt. Graham International Obs., Arizona  1993 72-Inch Perkins Telescope  1.83 m  72″  Single   USA  Lowell Observatory, Anderson Mesa USA  1964 Plaskett telescope  1.83 m  72″  Single  Great Britain  Dominion Astrophysical Observatory, Canada  1918Copernico 182 cm 1.82 m  72″  Single  Italy  Asiago Observatory, Italy (1350 m)  1973 1.8m Ritchey Cretien reflector  1.8 m  72″  Single  Korea   Bohyunsan Optical Astronomy Observatory, Korea  1996Sandy Cross Telescope  1.8 m  71″  Single  Canada  Rothney Astrophysical Observatory  1996 Spacewatch 1.8-meter Telescope  1.8 m  71″  Single  USA Kitt Peak National Observatory, USA 2001 69-inch Perkins Telescope  1.75 m    69″  Single  USA  Perkins Observatory, Ohio  1931–1964  165 cm telescope  1.65 m  65″  Single      Moletai Astronomical Obs., Lithuania  1991McMath-Pierce Solar Telescope  1.61 m  63″  Single  USA  Kitt Peak National Obs., USA  1962  50px AZT-33  1.6 m  63″  Single    Sayan Solar Obs., Siberia (2000m)  1981 1.6 m Perkin Elmer  1.6 m  63″  Single  Brazil  Pico dos Dias Observatory  1981 1.6  1.6 m  63″  R/C  Canada  Mont Mégantic Observatory, Canada  1978 Kaj Strand Telescope 1.55 m  61″  Single  USA  USN Obs. Flagstaff Station, USA  1964 61" Kuiper Telescope  1.55 m  61″  Single  USA  Steward Obs., Mt. Bigelow, USA  1965 Oak Ridge Observatory 61" reflector (Wyeth)  1.55 m  61″  Single  USA   Oak Ridge Observatory, Massachusetts, USA  1933-2005 Estación Astrofísica de Bosque Alegre  1.54 m  60.6″ Single   Argentina  Estación Astrofísica de Bosque Alegre, Argentina   1942 Danish 1.54 meter telescope  1.54 m  60.6″   Single  Denmark  La Silla Observatory, Chile  1979 Harvard 60-inch Reflector   1.524 m  60″  Single  United States  Harvard College Observatory, USA  1905–1931 60-Inch Telescope  1.524 m 60″  Single  United States  Mt. Wilson Observatory; California  1908  50px Dunn Solar Telescope ex-VTT  1.524 m 60″  Single  USA  National Solar Obs.-Sacramento Peak, USA1969 Palomar Observatory 60 inch 1.524 m  60″  Single  USA   Palomar Observatory, California, USA  1970  FLWO 1.5m Tillinghast  1.52 m 60″  Single  United States  F. L. Whipple Obs., Arizona  1994 Telescopio Carlos Sánchez (TCS)  1.52 m  60″  Single  UK + Spain  Teide Observatory, Tenerife (Spain)  1971 OHP 1.52  1.52 m  60″ Single   France  Haute-Provence Obs., France  1967  Mt. Lemmon 60" Telescope  1.52 m  60″  Single  USA  Steward Observatory, Mount Lemmon, USA 1970 OAN 1.52 m   1.52 m  60″ Single  Spain  Calar Alto Observatory, Spain  1970s 152 cm G.D. Cassini  1.52 m  60″ Single   Italy  Mount Orzale, Italy   1976 TIRGO (Gornergrat Infrared Telescope)   1.50 m  59″  Single IR  Italy + Switzerland  Hochalpine Forschungsstation Jungfraujoch und Gornergrat, Alps, Switzerland (3150 m) 1979–2005 AZT-22  1.5 m 59″  Single  USSR, Uzbekistan  Mount Maidanak, Uzbekistan  1972 AZT-20   1.5 m 59″  Single   Assy-Turgen Observatory, Kazakhstan   AZT-12  1.5 m 59″  Single  USSR, Estonia  Tartu Observatory, Estonia  1976 RTT-150  1.5 m 59″  Single  Russia, Turkey  TÜBİTAK National Observatory, Turkey  2001 OSN 1.5m (Nasmyth)  1.5 m 59″  Single  Spain  Sierra Nevada Obs., Spain (2896 m)  1991 BST-1M   1.5 m 59″  Single IR  USSR  Salyut 6, Earth Orbit  1977–1982 USNOFS 1.3m  1.3 m 51″  Single  USA USN Obs. Flagstaff Station, USA  1998 Warsaw Telescope  1.3 m  51″  Single  Poland  Las Campanas Obs., Chile  1996 Skinakas 1.3m Telescope1.3m51SingleGreeceSkinakas Obs., Greece1995 McGraw-Hill Telescope  1.27 m  50″  Single  USA  MDM Observatory, Arizona (1975–Present)Stinchfield Woods, Michigan (1969–1975)  1969 Great Melbourne Telescope (refit) 127 cm  50″  Single  Australia  Mount Stromlo Observatory, Australia  1961–1973 1992–2003 AZT-11  1.25 m  49″  Single    Abastumani Obs., Georgia (country)  1976  AZT-11  1.25 m  49″  Single    Crimean Astrophysical Obs., Ukraine  1981  MPIA 1.2  1.23 m  48.4″  Single  West Germany + Spain  Calar Alto Obs., Spain  1975 Babelsberg Zeiss   1.25 m  49″ Single  Germany, USSR Babelsberg Observatory; Berlin, Germany, Crimean Astrophysical Observatory (1952–present)  1924 Galileo 122 cm  1.22 m  48″ Single  Italy  Asiago Observatory, Italy  1942 Samuel Oschin telescope   1.22 m  48″  Schmidt  USA  Palomar Observatory; California  1948 OHP 1.20  1.2 m  48″ Single   France  Haute-Provence Obs., France  1943  Paris 48″ Reflector  1.2 m  48″   France  Paris Observatory, France  1871–1943 Great Melbourne Telescope  122 cm  48″   reflector – metal  Australia  Melbourne Observatory, Australia  1878–1944 Oskar-Lühning Telescope  1.2 m  47″  Single  Germany  Hamburg Observatory, Germany  1975 Leonhard Euler Telescope   120 cm  47″  Single  Switzerland   La Silla, Chile  1998 Mercator Telescope  120 cm  47″  Single  Belgium+Switzerland  ORM; La Palma, Canary Islands  2001 Hamburg Robotic Telescope (HRT)  120 cm  47″  Single  Germany Hamburg-Bergdorf Obs., Germany  2002* Hänssgen's reflector  107 cm  42″  Single  Germany  Mobile (~Germany)  2002* Omicron@C2PU104 cm41"SingleFranceObservatoire de la Côte d'Azur – Calern site, France, IAU code: 0102013 Epsilon@C2PU104 cm41"SingleFranceObservatoire de la Côte d'Azur – Calern site, France, IAU code: 0102015 Grubb Parsons 40-inch  102 cm  40″  Single  Sweden  Stockholm Observatory in Saltsjöbaden  1930–present Nickel Telescope  102 cm  40″  Single  USA  Lick Observatory, USA  1979  50px Grubb 40-inch  102 cm  40"  Single  USSR  Crimean Astrophysical Observatory Simeiz (destroyed in WWII)  1925–1944 George Ritchey 40-inch (1 m)  102 cm  40″  R/C  USA  Flagstaff, Arizona (Washington, D.C. until 1955), USA 1934 Yerkes "41-inch"  102 cm  40″ Single  USA  Yerkes Observatory, USA  1968 Meudon Observatory 1m  100 cm  39.4″  Single  France  Meudon Observatory/ Paris Observatory  1891 ZIMLAT  100 cm  39.4″  Single  Switzerland  Zimmerwald Obs., Switzerland  1997OGS Telescope 100 cm  39.4″  Single  European Space Agency countries  Teide Observatory, Tenerife, Spain  1995Jacobus Kapteyn Telescope  100 cm  39.4″  Single  UK + Netherlands  Isaac Newton Group, Canary Islands  1984  50px Lulin One-meter Telescope (LOT) 100 cm    39.4″  Single  ROC (Taiwan) Lulin Observatory, Taiwan   2002* ''Zeiss di Merate'' (1m reflector)   100 cm  39.4″  Single Kingdom of Italy  Merate Obs., Merate, Italy  1926  50px  Zeiss 1m reflector   100 cm  39.4″  Single  Belgium  Royal Obs., Uccle, Belgium  1920s Hamburg ''Spiegelteleskop'' (1m reflector) 100 cm  39.4″  Single  Deutsches Reich (Germany) Hamburg-Bergdorf Obs., Germany  1911  50px 1-m Carl Zeiss Jena   100 cm  39.4″  Single  CCCP  Assy-Turgen Observatory, Kazakhstan  James Gregory Telescope  94 cm  37"  SCT Great Britain  University of St Andrews, UK  1962  50pxSchmidt 92/67 cm 92 cm  36″  Schmidt  Italy  Cima Ekar Observatory, Asiago, Italy (1360 m)  1966Kuiper Airborne Obs. (KAO)  91.4 cm  36″  Single  USA   C-141 (mobile)   1974–1995Stratoscope 2  91.4 cm  36″  Single  USA  Balloon (mobile)  1961–1973 Crossley Reflector  91.4 cm  36″  Single  US+UK  Lick Observatory, USA  1896   50px 36-inch Yapp reflector  91.44 cm  36″   Reflector  UK  Greenwich & Herstmonceux  1932  50pxThis table does not include all the 20th largest mirrors manufactured; the Steward Observatory Mirror Lab produced the 6.5-metre f/1.25 collimator used in the Large Optical Test and Integration Site of Lockheed Martin, used for vacuum optical testing of other telescopes.Segmented are also known as Mosaic mirrors. Single mirrors, also called monolithic and can be sub-categorized in types, such as solid or honeycomb.
Selected telescopes with apertures of 90 cm (35.4 in.) and smaller Some famous 20th century regionally famous telescopes, space telescopes, or otherwise significant. (100 cm = 1 meter)  Name  Aperture m Aper. in  Mirror/type   Nationality/Sponsors  Site  Built/Used  Hopkins Ultraviolet Telescope  90 cm  35.4"  Single UV  USA  STS, Earth Orbit  1990, 1995 Meudon Great Refractor  83 cm  32.67"  refractor (visual)  France  Meudon, France  1891  50px 83-cm Reflector, Toulouse Observatory 83 cm  32.67"  reflector-glass  France  Toulouse, France  1875  50px Focault 80 cm, Marseille Observatory 80 cm 31.5"  reflector-glass  Focault Marseille, France   1862–1965 Astron  80 cm   31.5"  Single UV  CCCP + France  Earth orbit  1983–1989 Potsdam Great Refractor (double refractor)  80 cm   31.5"  Doublet  Germany  Potsdam, Germany  1899  50px Ruisinger 76.2 cm  30"  Single-Newtonian   United States (ASKC)   Louisburg, Kansas – Powell Obs. 1985 Greenwich 28 inch refractorRoyal Observatory, Greenwich 71 cm  28"  Doublet  British Empire  Greenwich, EnglandHerstmonceux, England, UK 1893  50px Meudon Great Refractor  62 cm   refractor (photographic-blue)  France  Meudon, France  1891  50px Infrared Space Observatory  60 cm  23.5" IR (2.4-240 μm) European Space Agency  Earth orbit (GEO)  1995–1998 IRAS    57 cm  22.44"  R/C IR  US + UK + The Netherlands  Earth orbit  1983  50px Mons Telescope  50 cm  19.7" Single   Belgium  Teide Observatory, Tenerife (Spain)  1972 Dutch Open Telescope (DOT)  45 cm  17.7"  Solar  Denmark  ORM, Canary Islands   1997 Explorer 57 (IUE)  45 cm  17.7"  Single UV  US+UK+ESA Countries   Earth orbit (GEO)  1978–1996 Glazar UV telescope 40 cm  15.75"  Single UV  CCCP  Kvant-1 (Mir), Earth Orbit  1987–2001  Glazar 2 UV telescope 40 cm  15.75"  Single UV  CCCP + Switzerland  Kristall (Mir), Earth Orbit  1990–2001  Mars Global SurveyorMOC  35 cm  13.8"   R/C  USA  Mars Orbit  1996–2006Griffith Observatory 12-inch Zeiss refractor 30.5 cm  12"  Achromat  USA L.A., USA 1931  50pxXMM-NewtonUV camera 30 cm  11.9"   Single UV  ESA Countries  Earth orbit  1998TRACE 30 cm  11.9"   Single EUV/UV/Vis  NASA  Earth orbit  1998–2010Hipparcos  29 cm  11.4"  Schmidt  European Space Agency  Earth orbit (GTO)   1989–1993Astronomical Netherlands Satellite   22 cm  8.7"  Single UV  Nederlands & USA  Earth Orbit  1974–1976 Galileo – Solid State Imager 17.65 cm  6.95"  Reflector  USA  Jupiter  1989–2003  Voyager 1/2, ISS-NAC  17.6 cm  6.92"  Catadioptric  USA  Space  1977 Spacelab IRT 15.2 cm 6"  IR (1.7–118 μm)  ESA + NASA  STS, Earth Orbit  1985 Mariner 10 – TV Photo. (x2)  15 cm  5.9"  Reflector  USA  Space  1973–1975Deep Space 1MICAS  10 cm  3.94"   Single  USA  Solar Orbit  1998–2001Far Ultraviolet Camera/Spectrograph 7.62 cm  3"  Schmidt UV  USA   Lunar surface  1972 Voyager 1/2, ISS-WAC  6 cm  2.36"  Lens  USA  Space  1977At the end of the 20th century preliminary designs for Extremely large telescope of the 21st century were being worked on, as well as many smaller telescopes such as the Large Binocular Telescope
Under Construction Examples of telescopes that were started in the 20th century, but may only have achieved a preliminary level of construction by the turn of the century. Name/Observatory  Aperture m Aper. in  Mirror type   Nationality of Sponsors  Site and/or Observatory  FL or Built GTC   10.4 m  409" Segmented,36 Spain (90%), Mexico(5%), USA(5%)  Roque de los Muchachos Observatory, La Palma  2007Faulkes Telescope North  2 m  79" Single  UK  Haleakala Observatory, Hawaii, USA  2003
Refractors
See also * List of largest optical telescopes in the 19th century* List of largest optical telescopes in the 18th century* Lists of telescopes* List of largest optical reflecting telescopes* List of optical telescopes** List of large optical telescopes* List of largest optical telescopes historically* List of astronomical interferometers at visible and infrared wavelengths
References * *  google units calculator
Further reading * List of large reflecting telescopes* The World's Largest Optical Telescopes*"The Astronomical Scrapbook", Joseph Ashbrook, Sky Publishing Corporation 1984, *"Giant Telescopes of the World", Sky and Telescope, August 2000*"The History of the Telescope", Henry C. King, (1955)*"The Historical Growth of Telescope Aperture", René Racine, Publications of the Astronomical Society of the Pacific, p. 116* JRASC (1929) vol 23, p. 351* Sky & Telescope (April 1981), p. 303* Sky & Telescope (July 1993) vol 86, pp. 27–32* James H. Burge, 1993 Dissertation at UA, "Advanced Techniques for Measuring Primary Mirrors for Astronomical Telescopes"
External links *  List of large reflecting telescopes*  The World's Largest Optical Telescopes*  Largest optical telescopes of the world*  Selected largest telescopes*  Stellafane telescope links