R e f l e c t i n g   T e l e s c o p e s   U n d e r   C o n s t r u c t i o n
Clear Aperture (meters) Telescope Name Observatory Location Date of Operation M1 F# Mirror Material Mirror Type Aspect Ratio Mirror Blank by Mirror Polish by Mounting Type Mounting Made by Mass Metric Tons Aperture Equiv. Meters Area Sq. Meters Baseline Cost Ref. Web Address
3.6 Devasthal 3.6m Devasthal Observatory Devasthal, India 2014 2.0 Schott Zerodur Meniscus 21.8 Schott LZOS Alt-Az AMOS 150         http://
2.55 T250 Javalambre Astrophysical Observatory Aragon, Spain 2015 3.5 Schott Zerodur Meniscus   Schott AMOS Alt-Az AMOS           http://www.cefca.es
8.4 LSST - Large Synoptic Survey Telescope Cerro Tololo Inter-American Observatory Cerro Pachon, Chile 2015 1.25 Ohara E6 Honeycomb   SOML-UA SOML-UA Alt-Az             http://www.lsst.org/
6.5 TAO - Tokyo Atacama Observatory   Cerro Chajnantor, Chile 2017 1.25 Ohara E6 honeycomb 9 SOML-UA SOML-UA Alt-Az Nishimura           http://www.ioa.s.u-tokyo.ac.jp/TAO/
7 x 8.4 GMT - Giant Magellan Telescope Las Campanas Observatory Cerro Las Campanas, Chile 2021 0.7 Ohara E6 Honeycomb   SOML-UA SOML-UA Alt-Az             http://www.gmto.org
30 TMT - Thirty Meter Telescope   Mauna Kea, Hawaii 2021 1.0 Ohara ClearCeram Segmented       Alt-Az             http://www.tmt.org
39 E-ELT European Extremely Large Telescope   Cerro Armazones, Chile 2024     Segmented       Alt-Az             http://www.eso.org/public/teles-instr/e-elt.html


P r e s e n t l y   O p e r a t i n g   R e f l e c t i n g   T e l e s c o p e s
Clear Aperture (meters) Telescope Name Observatory Location Date of Operation M1 F# Mirror Material Mirror Type Aspect Ratio Mirror Blank by Mirror Polish by Mounting Type Mounting Made by Mass Metric Tons Aperture Equiv. Meters Area Sq. Meters Baseline Cost Ref. Web Address
2 x 8.408 LBT - Large Binocular Telescope Mt. Graham International Observatory Mt. Graham, Arizona 2005 1.14 Ohara E6 Honeycomb 9.4 SOML-UA SOML-UA Alt-Az Ansaldo Energia 530 11.82 109.7     http://www.lbto.org
10 Hexagonal Keck I W. M. Keck Observatory Mauna Kea, Hawaii 1992 1.75 Schott Zerodur Segmented 24 Schott Itek/Tinsley Kodak Alt-Az Schwartz-Hautmont, TIW 273 10.55 87.5     http://www.keckobservatory.org/
10 Hexagonal Keck II W. M. Keck Observatory Mauna Kea, Hawaii 1996 1.75 Schott Zerodur Segmented 24 Schott Itek/Tinsley Kodak Alt-Az Coast Steel 273 10.55 87.5     http://www.keckobservatory.org/
10 Hexagonal GTC - Gran Telescopio Canarias Obs. Roque de los Muchachos La Palma, Canary Islands 2007 1.65 Schott Zerodur Segmented 24 Schott SAGEM Alt-Az Schwarz-Hautmont   10.36 84.2     http://www.gtc.iac.es/
9.5 HET - Hobby-Eberle Telescope McDonald Observatory Mt. Fowlkes, Texas 1997 1.8 Schott Zerodur Segmented 20 Schott Kodak Transit Comsat/MERO   9.17 66 $14M web http://www.as.utexas.edu/mcdonald/het/het.html
9.5 SALT - Southern African Large Telescope South Africa Astronomical Observatory Sutherland, South Africa 2005 1.8 Astrositall Segmented 20 LZOS Kodak Transit BKS Advantech   9.17 66     http://www.salt.ac.za/
8.2 Subaru National Astronomical Observatory of Japan Mauna Kea, Hawaii 1999 1.8 Corning ULE Meniscus 41 Corning Contraves Alt-Az Mitsubishi 500 8.2 52.8     http://www.naoj.org/
8 VLT - Very Large Telescope
UT1 Antu		 European Southern Observatory Cerro Paranal, Chile 1998 1.75 Schott Zerodur Meniscus 46 Schott REOSC Alt-Az Ansaldo Energia 430 8 49.2     http://www.eso.org/
8 VLT - Very Large Telescope
UT2 Kueyen		 European Southern Observatory Cerro Paranal, Chile 1999 1.75 Schott Zerodur Meniscus 46 Schott REOSC Alt-Az Ansaldo Energia 430 8 49.2     http://www.eso.org/
8 VLT - Very Large Telescope
UT3 Melipal		 European Southern Observatory Cerro Paranal, Chile 2000 1.75 Schott Zerodur Meniscus 46 Schott REOSC Alt-Az Ansaldo Energia 430 8 49.2     http://www.eso.org/
8 VLT - Very Large Telescope
UT4 Yepun		 European Southern Observatory Cerro Paranal, Chile 2000 1.75 Schott Zerodur Meniscus 46 Schott REOSC Alt-Az Ansaldo Energia 430 8 49.2     http://www.eso.org/
8 Gemini North Mauna Kea Observatories Mauna Kea, Hawaii 1998 1.8 Corning ULE Meniscus 40 Corning REOSC Alt-Az TELAS 311 8.01 50.4     http://www.noao.edu/usgp/usgp.html
8 Gemini South Cerro Tololo Inter-American Observatory Cerro Pachon, Chile 2000 1.8 Corning ULE Meniscus 40 Corning REOSC Alt-Az TELAS 311 8.01 50.4     http://www.gemini.edu/
6.5 MMT Conversion Whipple Observatory Mt. Hopkins, Arizona 1999 1.25 Ohara E6 Honeycomb 9 SOML-UA SOML-UA Alt-Az TIW/deBartolomeis 118 6.44 32.6     http://www.mmto.org/
6.5 Magellan I - Walter Baade Las Campanas Observatory Cerro Manqui, Chile 2000 1.25 Ohara E6 Honeycomb 9 SOML-UA SOML-UA Alt-Az L&F 150 6.44 32.6     http://www.ociw.edu/Magellan/
6.5 Magellan II - Landon Clay Las Campanas Observatory Cerro Manqui, Chile 2002 1.25 Ohara E6 Honeycomb 9 SOML-UA SOML-UA Alt-Az L&F 150 6.44 32.6     http://www.ociw.edu/Magellan/
6 LZT - Large Zenith Telescope University of British Colombia Vancouver, Canada 2006 1.5 Mercury Liquid N/A U. Laval Gravity Transit             http://www.astro.ubc.ca/LMT/lzt.html
6 BTA - Bol'shoi Teleskop Azimultal'nyi Special Astrophysical Observatory Mt. Pastukhova (Caucasus), Russia 1976 4 Sitall Solid 6 LZOS LOMO Alt-Az LOMO 850   26     http://www.sao.ru/
5.08 Hale Palomar Observatory Palomar Mountain, California 1948 3.3 Pyrex Honeycomb   Corning Brown Horseshoe Yoke Westinghouse 482     $6M   http://www.astro.caltech.edu/palomar/hale.html
4.2 WHT - William Herschel Telescope Obs. Roque de los Muchachos La Palma, Canary Islands 1987 2.5 Cer-Vit Solid 8 Owens-Illinois Grubb-Parsons Alt-Az Grubb-Parsons 210         http://www.ing.iac.es
4.2 SOAR - Southern Observatory for Astrophysical Research Cerro Tololo Inter-American Observatory Cerro Pachon, Chile 2005 1.75 Corning ULE Meniscus 42 Corning Raytheon Alt-Az Vertex RSI           http://www.soartelescope.org
4.2 DCT - Discovery Channel Telescope Lowell Observatory Happy Jack, Arizona 2012 1.9 Corning ULE Meniscus 42 Corning OSC-UA Alt-Az General Dynamics SATCOM           http://www.lowell.edu/dct/
4.1 VISTA - Visible Infrared Survey Telescope for Astronomy European Southern Observatory Cerro Paranal, Chile 2008 1.0 Schott Zerodur Meniscus 24 Schott LZOS Alt-Az VertexRSI           http://www.vista.ac.uk/
4 Victor M. Blanco Cerro Tololo Inter-American Observatory Cerro Tololo, Chile 1976 2.8 Cer-Vit Solid 8 Owens-Illinois KPNO Horseshoe Western Gear 310 4 10.0     http://www.ctio.noao.edu/telescopes/4m/base4m.html
4 LAMOST - Schmidt Beijing Astronomical Observatory Xinglong, China 2008 5 Schott Zerodur Segmented   Schott LZOS
NIAOT		 Meridian             http://www.lamost.org/website/en/
3.89 AAT - Anglo-Australian Telescope Anglo-Australian Observatory Siding Spring, New South Wales 1975 3.3 Cer-Vit Solid   Owens-Illinois Grubb-Parsons Horseshoe Mitsubishi           http://www.aao.gov.au/
3.81 Nicholas U. Mayall Kitt Peak National Observatory Kitt Peak, Arizona 1973 2.8 Fused Quartz Solid   General Electric KPNO Horseshoe Western Gear           http://www.noao.edu/kpno/kpno.html
3.8 UKIRT - United Kingdom InfraRed Telescope Mauna Kea Observatories Mauna Kea, Hawaii 1978 2.5 Cer-Vit Meniscus 13.2 Owens-Illinois Grubb-Parsons English Yoke Hadfields Ltd.       $5.6M Tele. ... 1990s http://www.jach.hawaii.edu/JACpublic/UKIRT/home.html
3.67 AEOS 3.7m Air Force Maui Optical Station Haleakala, Hawaii 1996 3.0 Schott Zerodur Meniscus 23 Schott Contraves Alt-Az Contraves           http://ulua.mhpcc.af.mil/
3.58 CFHT - Canada-France-Hawaii Telescope Mauna Kea Observatories Mauna Kea, Hawaii 1979 3.8 Cer-Vit Solid   Owens-Illinois DAO Horseshoe Yoke SNACRP           http://www.cfht.hawaii.edu/
3.57 ESO 3.6m European Southern Observatory Cerro La Silla, Chile 1977 3 Fused Silica Solid 6 Corning REOSC Horseshoe Fork Creusot-Loire 200         http://www.ls.eso.org/lasilla/Telescopes/360cat/html/tel360.html
3.5 NTT - New Technology Telescope European Southern Observatory Cerro La Silla, Chile 1989 2.2 Schott Zerodur Meniscus 14.9 Schott Zeiss Alt-Az INNSE 110         http://www.ls.eso.org/lasilla/Telescopes/NEWNTT/
3.5 MPI 3.5m German-Spanish Astronomical Center Calar Alto, Spain 1984 3.5 Schott Zerodur Solid 5.8 Schott Zeiss Horseshoe Yoke VOITH/MAN 400     DM 55e6 Tele. ... 1990s http://www.mpia-hd.mpg.de/Public/CAHA/
3.5 USAF Phillips Lab 3.5m Starfire Optical Range Albuquerque, New Mexico 1994 1.5 Ohara E6 Honeycomb 7.4 SOML-UA SOML-UA Alt-Az Contraves           http://www.de.afrl.af.mil/pa/factsheets/35meter.html
3.5 WIYN - Wisconsin Indiana Yale NOAO Kitt Peak National Observatory Kitt Peak, Arizona 1994 1.75 Ohara E6 Honeycomb   SOML-UA SOML-UA Alt-Az L&F           http://www.noao.edu/wiyn/wiyn.html
3.5 TNG - Telescopio Nazionale Galileo Obs. Roque de los Muchachos La Palma, Canary Islands 1997 2.2 Schott Zerodur Meniscus 14.9 Schott Zeiss Alt-Az Ansaldo Camozzi           http://www.pd.astro.it/TNG/TNG.html
3.5 SST - Space Surveillance Telescope White Sands Missile Range White Sands, New Mexico 2011 Alt-Az        
3.48 ARC - Astrophysical Research Consortium Apache Point Observatory Sacramento Peak, New Mexico 1994 1.75 Ohara E6 Honeycomb   SOML-UA SOML-UA Alt-Az L&F           http://www.apo.nmsu.edu/
3.05 Shane 120-inch Lick Observatory Mt. Hamilton, California 1959 5 Pyrex Honeycomb   Corning Hendrix Fork equatorial Judson Pacific-Murphy           http://www.irving.org/xplore/lick/contents.html
3 IRTF - Infrared Telescope Facility NASA Mauna Kea, Hawaii 1979 2.5 Cer-Vit Solid   Owens-Illinois KPNO English Yoke deBartolomeis           http://irtf.ifa.hawaii.edu/
2.72 Harlan J. Smith 107-inch McDonald Observatory Mt. Locke, Texas 1969 3.93 Fused Silica Solid 8.6 Corning Davidson English Yoke Westinghouse 165         http://www.as.utexas.edu/mcdonald/facilities/2.7m/2.7.html
2.7 LMT University of British Colombia Vancouver, Canada 1992 1.887 Mercury Liquid N/A U. Laval Gravity Transit             http://www.astro.ubc.ca/LMT/lmt.html
2.64 Shajn Crimean Astrophysical Observatory Simeis, Ukraine 1961 3.85 Sitall Solid     LOMO Fork equatorial LOMO           http://www.crao.crimea.ua/craoinfo/stella.html
2.61 VST - VLT Survey Telescope European Southern Observatory Cerro Paranal, Chile 2009 1.8 Astrositall Meniscus 19 LZOS Zeiss
LZOS		 Alt-Az             http://vstportal.oacn.inaf.it/
2.6 2.6m Byurakan Astrophysical Observatory Mt. Aragatz, Byurakan, Armenia 1976 3.85 Sitall Solid     LOMO Fork equatorial LOMO           http://bao.sci.am/
2.56 NOT - Nordic Optical Telescope Obs. Roque de los Muchachos La Palma, Canary Islands 1989 2 Schott Zerodur Meniscus 13.5 Schott Tuorla Optical Lab. Alt-Az             http://www.not.iac.es/
2.54 Irenee duPont Las Campanas Observatory Las Campanas, Chile 1976 3 Fused Silica Solid 6.57 Corning Loomis Fork equatorial L&F           http://www.ociw.edu/lco/
2.54 Hooker 100-inch Mt. Wilson Observatory Mt. Wilson, California 1917 5 Glass Solid   St. Gobain Ritchey English Yoke             http://www.mtwilson.edu/
2.54 INT - Isaac Newton Telescope Obs. Roque de los Muchachos La Palma, Canary Islands 1984 2.94 Schott Zerodur Solid   Schott Grubb-Parsons Polar-disk Equatorial             http://www.ing.iac.es
2.5 SDSS - Sloan Digital Sky Survey Apache Point Observatory Sacramento Peak, New Mexico 1997 2.25 Ohara E6 Honeycomb   Hextek OSC-UA Alt-Az L&F 22         http://www.sdss.org/sdss.html


F o r m e r l y   O p e r a t i n g   R e f l e c t i n g   T e l e s c o p e s
Clear Aperture (meters) Telescope Name Observatory Location Date of Operation M1 F# Mirror Material Mirror Type Aspect Ratio Mirror Blank by Mirror Polish by Mounting Type Mounting Made by Mass Metric Tons Aperture Equiv. Meters Area Sq. Meters Baseline Cost Ref. Web Address
3.5 LOT - Large Optical Telescope Iraqi National Astronomical Observatory Mt. Korek, Erbil, (Kurdistan) Iraq ?? 3.4 Schott Zerodur Solid 6 Schott Zeiss Horseshoe Yoke Zeiss            
3 LMT NASA Orbital Debris Observatory Sacramento Peak, New Mexico 1995-2002 1.725 Mercury Liquid N/A U. Laval Gravity Transit             http://www.astro.ubc.ca/lmt/Nodo/index.html


M i r r o r s   R e t i r e d   f r o m   T e l e s c o p e s
Clear Aperture (meters) Telescope Name Observatory Location Date of Operation M1 F# Mirror Material Mirror Type Aspect Ratio Mirror Blank by Mirror Polish by Mounting Type Mounting Made by Mass Metric Tons Aperture Equiv. Meters Area Sq. Meters Baseline Cost Ref. Web Address
6 BTA - Bol'shoi Teleskop Azimultal'nyi Special Astrophysical Observatory Mt. Pastukhova, Russia 1976 4 Borosilicate
# 316		 Solid                     http://www.sao.ru/
2.5 INT - Isaac Newton Telescope Royal Greenwich Observatory Greenwich, England 1967-1981 3 Borosilicate Solid                     http://www.ing.iac.es
6 x 1.8 MMT (old) Whipple Observatory Mt. Hopkins, Arizona 1979 2.7 Fused Silica Honeycomb   Corning OSC-UA       4.6        

This list of telescopes compiled by John M. Hill, Large Binocular Telescope Observatory, University of Arizona, jhill@as.arizona.edu
Large solar and space telescopes have not yet been included in the list.
BIBLIOGRAPHY
  • JRASC (1929) vol 23, p351
  • Sky&Telescope (April 1981) p303
  • Mercury (Sep-Oct 1982) p142 (from Pasachoff)
  • King, Henry C. "The History of the Telescope"
  • Sky&Telescope (July 1993) vol 86, p 27-32
  • James H. Burge, 1993 Dissertation at UA, "Advanced Techniques for Measuring Primary Mirrors for Astronomical Telescopes"
  • many SPIE Proceedings (4837, 4004, 3352, 2871, 2199, 1236, 628, 444, 332)
  • Sky&Telescope (August 2000) vol 100, p 43-51