List of largest optical reflecting telescopes

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The two Keck telescopes

This list of the largest optical reflecting telescopes with objective diameters of 3.0 metres (120 in) or greater is sorted by aperture, which is one limit on the light-gathering power and resolution of a reflecting telescope's optical assembly. The mirrors themselves can be larger than the aperture, and telescopes may use aperture synthesis achieved by interferometry. Telescopes designed to be used as optical astronomical interferometers such as the Keck I and II used together as the Keck Interferometer (up to 85 m) can reach very high resolutions, although at a narrower range of observations. When the two mirrors are on one mount, the combined mirror spacing of the Large Binocular Telescope (22.8 m) allows fuller use of the aperture synthesis.

Largest does not always equate to being the best telescopes, and overall light gathering power of the optical system can be a poor measure of a telescope's performance. Space-based telescopes, such as the Hubble Space Telescope, take advantage of being above the Earth's atmosphere to reach higher resolution and greater light gathering through longer exposure time. Location in the northern or southern hemisphere of the Earth can also limit what part of the sky can be observed.

Table of reflecting telescopes[edit]

This list is ordered by optical aperture, which has historically been a useful gauge of limiting resolution, optical area, physical size, and cost. Multiple mirror telescopes that are on the same mount, may have a working beam combiner, and can form an image may be ranked by an equivalent aperture to this reported by sources. HET-style or fixed telescopes are ranked by an equivalent aperture also.

Name Image Effective aperture
m
Aper.
in
Mirror type Nationality / Sponsors Site Built
Gran Telescopio Canarias (GTC) Grantelescopio.jpg 10.4 m 409″ Segmented, 36 Spain (90%), Mexico, USA Roque de los Muchachos Obs., Canary Islands, Spain 2006/9
Keck 1 KeckTelescopes-hi.png 10 m 394″ Segmented, 36 USA Mauna Kea Observatories, Hawaii, USA 1993
Keck 2 KeckTelescopes-hi.png 10 m 394″ Segmented, 36 USA Mauna Kea Observatories, Hawaii, USA 1996
Southern African Large Telescope (SALT) [1] (11 m × 9.8 m mirror) Southern African Large Telescope 720x576px.jpg 9.2 m 362″ Segmented, 91 South Africa, USA, UK, Germany, Poland, New Zealand South African Astronomical Obs., Northern Cape, South Africa 2005
Hobby-Eberly Telescope (HET) (11 m × 9.8 m mirror) HET Dome.jpg 9.2 m 362″ Segmented, 91 USA, Germany McDonald Observatory, Texas, USA 1997
Large Binocular Telescope (LBT) (Phased-array optics for combined 11.9 m[2]) LBT-Gebaeude.jpg 8.4 m × 2 330″ × 2 Multiple mirror, 2 USA, Italy, Germany Mount Graham Internationals Obs., Arizona 2004
Subaru (JNLT) MaunaKea Subaru.jpg 8.2 m 323″ Single Japan Mauna Kea Observatories, Hawaii, USA 1999
VLT UT1 (Antu) Paranal opendome.jpg 8.2 m 323″ Single ESO Countries, Chile Paranal Observatory, Antofagasta Region, Chile 1998
VLT UT2 (Kueyen) Paranal1.jpg 8.2 m 323″ Single ESO Countries, Chile Paranal Observatory, Antofagasta Region, Chile 1999
VLT UT3 (Melipal) Paranal1.jpg 8.2 m 323″ Single ESO Countries, Chile Paranal Observatory, Antofagasta Region, Chile 2000
VLT UT4 (Yepun) Paranal1.jpg 8.2 m 323″ Single ESO Countries, Chile Paranal Observatory, Antofagasta Region, Chile 2001
Gemini North (Gillett) Gemini Observatory at sunset.jpg 8.1 m 318″ Single USA, UK, Canada, Chile, Australia, Argentina, Brazil Mauna Kea Observatories, Hawaii, USA 1999
Gemini South Gemini South 01.jpg 8.1 m 318″ Single USA, UK, Canada, Chile, Australia, Argentina, Brazil Cerro Pachón (CTIO), Coquimbo Region, Chile 2001
MMT (1 x 6.5 M1) MMT Observatory.jpg 6.5 m 256″ Single USA F. L. Whipple Obs., Arizona, USA 2000
Magellan 1 (Walter Baade)[3] Magellan telescopes.jpg 6.5 m 256″ Honeycomb USA Las Campanas Obs., Coquimbo Region, Chile 2000
Magellan 2 (Landon Clay) Magellan telescopes.jpg 6.5 m 256″ Honeycomb USA Las Campanas Obs., Coquimbo Region, Chile 2002
BTA-6 Главная обсерватория.jpg 6 m 238″ Single USSR/Russia Special Astrophysical Obs., Karachay–Cherkessia, Russia 1975
Large Zenith Telescope (LZT) 6 m 236″ Liquid Canada, France, USA [4] Maple Ridge, British Columbia, Canada 2003
Hale Telescope (200 inch) P200 Dome Open.jpg 5.08 m 200″ Single USA Palomar Observatory, California, USA 1948
LAMOST (6.67 m × 6.05 m + 5.72 m × 4.40 m corrector; effective aperture 3.6–4.9 m) LAMOST telescope org.jpg 4.9 m–3.6 m[5] 193″ Segmented
(37 + 24)[6]
PRC (China) Beijing Astronomical Obs., Xinglong, China 2008
MMT (6×1.8 m) original optics 4.7 m
(6×1.8 m) [7]
186″ Segmented, 6 USA F. L. Whipple Obs., Arizona, USA 1979–1998
Discovery Channel Telescope[8] The Dome of Discovery Channel Telecope.JPG 4.3 m 169″ Single USA Lowell Observatory, Happy Jack, Arizona 2012
William Herschel Telescope William herschel Telescope Dome.jpg 4.2 m 165″ Single UK, Netherlands, Spain Roque de los Muchachos Obs., Canary Islands, Spain 1987
SOAR 4.1 m 161″ Single USA, Brazil Cerro Pachón (CTIO), Coquimbo Region, Chile 2002
VISTA VISTA at Paranal Eso0704b.tif 4.1 m 161″ Single ESO Countries, Chile Paranal Observatory, Antofagasta Region, Chile 2009
Victor M. Blanco Telescope 4m-Victor M. Blanco Telescope.jpg 4 m 157″ Single USA Cerro Tololo Inter-American Obs., Coquimbo Region, Chile 1976
Nicholas U. Mayall 4m[9] Kittpeakteliscope.JPG 4 m 149.5″ Single USA Kitt Peak National Obs., Arizona, USA 1973
Anglo-Australian Telescope (AAT) Anglo-Australian Telescope dome.JPG 3.89 m 154″ Single Australia, UK Australian Astronomical Obs., New South Wales, Australia 1975
3.67m AEOS Telescope (AEOS) AEOS3 lg.jpg 3.67 m 145″ Single USA Air Force Maui Optical Station, Hawaii, USA 1996
Telescopio Nazionale Galileo (TNG) Tng 2001.jpg 3.58 m 138″ Single Italy Roque de los Muchachos Obs., Canary Islands, Spain 1997
New Technology Telescope (NTT) La Silla NTT.jpg 3.58 m 142″ Single ESO countries La Silla Observatory, Coquimbo Region, Chile 1989
Canada-France-Hawaii Telescope (CFHT) Canada-France-Hawaii-Telescope-dome.jpeg 3.58 m 141″ Single Canada, France, USA Mauna Kea Observatories, Hawaii, USA 1979
ESO 3.6 m Telescope 3.6-m Telescope at La Silla.jpg 3.57 m 140″ Single ESO countries La Silla Observatory, Coquimbo Region, Chile 1977
MPI-CAHA 3.5 m[10] Bacares09.jpg 3.5 m 138″ Single West Germany, Spain Calar Alto Obs., Almería, Spain 1984
USAF Starfire 3.5 m [11] Big3 5mtele.png 3.5 m 138″ Single USA Starfire Optical Range, New Mexico, USA 1994
WIYN Telescope WIYN OBSERVATORY ON KITT PEAK.jpg 3.5 m 138″ Single USA Kitt Peak National Obs., Arizona, USA 1994
Space Surveillance Telescope Space Surveillance Telescope.jpg 3.5 m 138″ Single USA White Sands Missile Range, New Mexico, USA 2011
Astrophysical Research Consortium (ARC) D70050914 15 ApolloLLR.jpg 3.48 m 137″ Single USA Apache Point Obs., New Mexico, USA 1994
Shane Telescope Shane dome.JPG 3.05 m 120″ Single USA Lick Observatory, California, USA 1959
NASA Infrared Telescope Facility Afshin Darian - NASA Infrared Telescope Facility.jpg 3.0 m 120″ Single USA Mauna Kea Observatory, Hawaii, USA 1979
NASA-LMT[12] retired, Private Liquid Mirror Telescope.jpg 3 m 118″ Liquid USA NASA Orbital Debris Obs., New Mexico, USA 1995–2002
See List of large optical reflecting telescopes for continuation of list

There are only a few sites capable of polishing the mirrors for these telescopes. SAGEM in France polished the four VLT mirrors, the two Gemini mirrors, and the 36 segments for GTC.[13] The Steward Observatory Mirror Lab cast and polished the two LBT mirrors, the two Magellan mirrors and the MMT replacement mirror. It is currently making the LSST primary mirror and the mirrors for the Giant Magellan Telescope.[14] The Keck segments were made by Schott AG. The SALT and LAMOST segments were cast and polished by LZOS.[15] The mirror for Subaru was cast by Corning and polished at Contraves Brashear Systems in Pennsylvania.[16]

This table does not include all the 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 mirrors are also referred to as mosaic mirrors. Single mirrors are also referred to monolithic mirrors, and can be sub-categorized in types, such as solid or honeycomb.

Comparison of nominal sizes of primary mirrors of some notable optical telescopes (click for detail)
For the largest reflecting telescopes on the planet, the horizontal indicates the year built and the vertical direction indicates the size of the mirror measured in meters. Countries which contain several of these telescopes are color-coded for identification.

Top telescopes of 2010[edit]

The largest telescopes are multi-telescope interferometers, and may have longer baselines. However, these astronomical interferometers are less flexible in use, and many interferometers cannot form images or see faint objects despite their high peak angular resolution.

The largest telescope during the first decade of the 21st century could be either the Gran Telescopio Canarias (one 10.4 m diameter mirror), the Large Binocular Telescope (two 8.4 m diameter mirrors on a binocular mount), or the Very Large Telescope (with four 8.2 m telescopes and four 1.8 m auxiliary telescopes). However, as these were still coming online in the period, the two 10 m Keck Telescopes (with 85 m aperture synthesis) were possibly the largest in full scientific operation.

Note other wavelengths of telescopes can be much larger physically, such as the 305 m aperture Arecibo radio telescope, but since radio wavelengths are also larger, this does not necessarily translate into brighter or higher resolution images.

Name Out In Aperture (m) Equiv. Area (m) Area (m2) Mirrors Note Altitude (m)
Gran Telescopio Canarias (GTC) Grantelescopio.jpg GranTeCan Mosaic.jpg 10.4 10.4 74 36 × 1.9 m hexagonal segments for M1 Commissioned 2009; Largest single mirror 2267
Southern African Large Telescope (SALT) Southern African Large Telescope 720x576px.jpg Salt Mirror.jpg 11 (max.) 9.2 66–45 92 × 1 m hexagon; 11 × 9.8 m mirror HET twin but larger optically. Spherical M1 w/ fixed mirror; spectroscopy (see here [2]) 1783
Keck 1 & 2 KeckObservatory20071020.jpg KeckObservatory20071013.jpg 10 m each 10 76 (each)[17] 36 × 1.8 m hexagons M1 mirrors each largest twin telescopes
152 m2 total optical area
4145
VLT 1, 2, 3 & 4 Very Large Telescope Array.aerial view.jpg Creating a Star.jpg 8.2 (each) 8.2 53 (each)
1 x 8.2 m M1 each Largest quadruplet telescope
210 (total optical area)
2635
Large Binocular Telescope (LBT) LBT-Gebaeude.jpg LBT 3.JPG 8.4 m each 11.7 111(both sides) 2 x 8.4 m M1 mirrors; 1 mount Largest Binocular; largest non-segmented mirrors; 22.8 m aperture planned [18] 3221

Largest telescopes with interferometer mode, and two image-forming interferometer arrays.

Name Longest baseline (m) Mirrors Area (m2) Equiv. Note
VLTI 200 4 × 8.2 m (VLT 1,2,3, & 4) 210 [19] 16 Behind schedule in 2010, 4 units at 130 m success in 2012[20]
Keck Interferometer 85 2 × 10 m (Keck 1 & 2) 152 [19] Operations ceased in 2012.[21]
Large Binocular Telescope (LBTI) 22.8* 2 × 8.4 m 110 [19] 11.9 One telescope mount*; Fizeau & Amplitude Interferometry
CHARA array 330 6 × 1 m 2.45 [22]
NPOI 437 6 siderostats (visible) Sparse Aperture [19] Optically resolved Mizar (star)

*Baseline does not reduce with viewing angle

Top telescopes of 2000[edit]

Name Out In Aperture (m) Area (m2) Mirrors Note Altitude (m)
Keck 1 & 2 KeckObservatory20071020.jpg KeckObservatory20071013.jpg 10 (each) 76 (each)[17] 36 × 1.8 m hexagons M1 mirrors each largest twin telescopes, largest aperture mirrors, 152 m2 total optical area 4145
Hobby-Eberly Telescope (HET) HET Dome.jpg Salt Mirror.jpg 9.2 (max.) 66–45 92 x 1 m hexagon; 11 × 9.8 m mirror Spherical M1 w/ fixed mirror; spectroscopy 2030
Subaru Telescope MaunaKea Subaru.jpg Subaru Telescope under daylight.jpg 8.2 53 1 × 8.3 m M1 Largest single piece mirror (tied with the 4 VLT) 4145
VLT 1,2,3, & 4 Very Large Telescope Array.aerial view.jpg Creating a Star.jpg 8.2 (each) 53 (each) 1 x 8.2 m M1 Largest quadruplet telescope; largest single piece mirrors (tied with Subaru) 2635

Chronologically[edit]

Years Largest Name Out In Aperture (m) Area (m2) M1 Mirror Note Altitude (m)
2009–Present Gran Telescopio Canarias Grantelescopio.jpg Gran Telescopio Canarias.jpg 10.4 74 36 × 1.9 m hexagons M1 mirror Segmented mirror 2267
1993–2009 Keck 1 KeckTwilight-hi.png KeckObservatory20071013.jpg 10 76 [17] 36 × 1.8 m hexagons M1 mirror Segmented mirror, M1 f/1.75 4145
1976–1993 BTA-6 Главная обсерватория.jpg SAO-6m-Telescope-main-mirror.jpg 6 26 605 cm f/4 M1 mirror Mirror replaced twice 2070
1948–1976 Hale (200 inch) P200 Dome Open.jpg Palomar arp 600pix.jpg 5.1 508 cm f/3.3 M1 mirror Art deco dome 1713
1917–1948 Hooker (100 inch) 100inchHooker.jpg 2.54 Also used for 1st optical interferometer 1742

For earlier top telescopes see List of largest optical telescopes historically

Plans[edit]

Below are selected telescopes that are still in the conceptual/proposed stage or still under construction.

Under construction or planned construction
Sketch of the Messier 51 by William Parsons in 1845, later known as the Whirlpool Galaxy
Whirlpool Galaxy (M51A/B or NGC 5194/5) by NASA/ESA from Hubble Space Telescope in 2005
Proposed or planned

See also[edit]

References[edit]

  1. ^ "Howstuffworks "10 Amazing Telescopes"". Science.howstuffworks.com. Retrieved August 19, 2009. 
  2. ^ SPIE 2006 in Orlando - Proceedings of SPIE conference 6267 on “Ground-based and Airborne Telescopes”, "The Large Binocular Telescope", John M. Hill, Richard F. Green and James H. Slagle
  3. ^ "The Carnegie Observatories – Magellan Telescopes". Ociw.edu. Retrieved August 19, 2009. 
  4. ^ The Telescope, By Geoff Andersen, Page 165
  5. ^ [1][dead link]
  6. ^ "LAMOST Homepage – Gallery". Lamost.org. June 22, 2008. Retrieved August 19, 2009. 
  7. ^ by Dwayne DayMonday, May 11, 2009 (2009-05-11). "Mirrors in the dark". The Space Review. Retrieved 2012-01-03. 
  8. ^ Lowell Observatory - DCT status
  9. ^ "The Mayall 4-Meter Telescope". Noao.edu. February 27, 1973. Retrieved August 19, 2009. 
  10. ^ "Max-Planck-Institut für Astronomie". Mpia.de. July 20, 1994. Retrieved August 19, 2009. 
  11. ^ John Pike. "Starfire". Globalsecurity.org. Retrieved August 19, 2009. 
  12. ^ "NASA Orbital Debris Observatory". Astro.ubc.ca. Retrieved August 19, 2009. 
  13. ^ "Polissage Optique pour les Grands Instruments de la Physique et de l ’Astronomie". 
  14. ^ "Mirror Castings". Steward Observatory Mirror Lab. 
  15. ^ "Large Optics Manufacturing in Large Optics Manufacturing in Lytkarino Optical Glass Factory, Russia". 
  16. ^ "SUBARU Telescope 8.3m Primary Mirror Finished". 
  17. ^ a b c "Keck Telescope Facts". Spacecraftkits.com. Retrieved 2012-01-03. 
  18. ^ http://lbti.as.arizona.edu/LBTI-Main/Project.html
  19. ^ a b c d "Telescope - Modern Optical Telescopes - Mirror, Diameter, Keck, and Honeycomb - JRank Articles". Science.jrank.org. Retrieved 2012-01-03. 
  20. ^ K. Moskvitch - Four telescope link-up creates world's largest mirror (2012) - BBC
  21. ^ KI
  22. ^ "Large Telescopes". Astro.nineplanets.org. Retrieved 2012-01-03. 
  23. ^ "E-ELT". ESO. Retrieved December 4, 2011. 
  24. ^ "Thirty Meter Telescope". Tmt.org. Retrieved August 19, 2009. 
  25. ^ "GMT – Technical Overview". Gmto.org. Retrieved August 19, 2009. 
  26. ^ "International Liquid Mirror Telescope – Extragalactic Astrophysics and Space Observations". Aeos.ulg.ac.be. Retrieved August 19, 2009. 
  27. ^ 3.6 m Devasthal Optical Telescope
  28. ^ New Telescope Projects - UH
  29. ^ "LLAMA". Astro.ubc.ca. Retrieved August 19, 2009. 
  30. ^ The Colossus

Further reading[edit]

  • "The Astronomical Scrapbook", Joseph Ashbrook, Sky Publishing Corporation 1984, ISBN 0-933346-24-7, o
  • "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, 116
  • JRASC (1929) vol 23, p351
  • Sky&Telescope (April 1981) p303
  • 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"
  • Bell, R.M. and Robins, G.C. and Eugeni, C. and Cuzner, G. and Hutchison, S.B. and Baily, S.H. and Ceurden, B. and Hagen, J. and Kenagy, K. and Martin, H.M. and Tuell, M. and Ward, M. and West, S.C. (July 2008). "LOTIS at completion of Collimator integration". "Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series" 7017. doi:10.1117/12.791889. 

External links[edit]