This is a list of the largest optical telescopes in the British Isles, including in the United Kingdom and Ireland.
Several historically important telescopes were located in this region. Those include William Herschel's reflecting 40-foot telescope, with which he discovered Uranus. The Leviathan of Parsonstown had the largest aperture in the world for several decades.
The largest optical telescope that ever operated in the British Isles was the Isaac Newton Telescope, which had a mirror. It was located at the Royal Greenwich Observatory, Herstmonceux from 1965 to 1980, but was then relocated to Roque de los Muchachos Observatory on La Palma, Canary Islands.
The British Isles no longer hosts large optical telescopes used for research. By the 20th century, the UK (and to a lesser extent Ireland) was building and operating large telescopes overseas, for better weather, seeing or access to different targets. Many older telescopes are now tourist attractions. There are also modest-sized telescopes at universities and science museums, used for student education, training, or outreach purposes.
Current list The following is a non-comprehensive list of optical telescopes currently located in the British Isles with an aperture of or greater:
+Reflecting telescopes Name Effective aperture Type Location Operator First light Notes Rosse Six Foot Telescope (reconstructed) Newtonian reflector Birr, Leinster Birr Castle 1999 Largest optical telescope in Ireland. 38-inch Congo Schmidt Reflector Herstmonceux, East Sussex The Observatory Science Centre 1960 Largest optical telescope in UK, but never used due to flawed optics. James Gregory Telescope Cassegrain reflector St Andrews, Fife University of St Andrews 1962 Largest operational optical telescope in the UK. Cambridge 36-inch telescope Reflector Cambridge, Cambridgeshire University of Cambridge 1955 Largest optical telescope still in use in England. 36-inch Yapp telescope Reflector Herstmonceux, East Sussex The Observatory Science Centre 1932 Edinburgh 36-inch telescope Reflector Edinburgh Royal Observatory Edinburgh 1930 No longer operational. 34-inch Hewitt Camera Reflector Herstmonceux, East Sussex The Observatory Science Centre 1950s Perren Telescope Ritchey–Chrétien reflector Mill Hill, London UCL Observatory 2019 Thomson/Regan/Owen Reflector Reflector Great Sutton, Cheshire David Thomson 2023 John Wall refractor Refractor Hanwell, Oxfordshire Hanwell Community Observatory 1999 Largest refractor in the British Isles. 30" Dobsonian Reflector Todmorden, West Yorkshire The Astronomy Centre 1986 Thompson 30-inch Reflector Reflector Herstmonceux, East Sussex The Observatory Science Centre 1896 Greenwich 28-inch refractor Refractor Greenwich, London Royal Observatory, Greenwich 1893 Moses Holden Telescope Reflector Preston, Lancashire University of Lancashire 2015 Thompson 26-inch Refractor Refractor Herstmonceux, East Sussex The Observatory Science Centre 1897 24 / 17" Schmidt Camera Reflector Knighton, Powys The Spaceguard Centre 1950 Largest optical telescope in Wales. Thornton Telescope Reflector Keele, Staffordshire Keele University 1975 24" Telescope Reflector Sherwood Observatory, Nottinghamshire Sherwood Observatory 1984 24" Telescope Reflector Bayfordbury, Hertfordshire University of Hertfordshire 2021
Historical Isaac Newton Telescope at Herstmonceux, (1965–1979) Leviathan of Parsonstown, 1842– 3-foot telescope at Parsons RGO telescopes at different points in its history 38-inch Hargreaves Reflector (1960) Yapp 36-inch Reflector (1932) 30-inch Steavenson Reflector (1939) 28-inch Refractor (1893) Thompson Telescope with a 26-inch refractor and 30-inch reflector on one mounting (1896) Lassell 2-foot Reflector (1845) Isaac Roberts 20-inch reflector (1885) Western Equatorial (c. 1824) 13-inch Astrographic Refractor (1890) Merz 12.8-inch Visual Refractor (1859–1893) (this was replaced by the 28-inch Grubb in the onion dome) Thomson 9-inch Photographic Refractor (c. 1888) Sheepshanks refractor 6.7-inch (1838) ( Sheepshanks Equatorial) 6-inch Franklin Adams Camera (1898) Shuckburgh telescope a 4.1-inch aperture Refractor (1791) At the Observatory Science Center (at Herstmonceux) Hargreaves 38-inch Congo Schmidt Yapp 36-inch reflector Thompson 30-inch reflector Thompson 26-inch reflector Markree Observatory 13.3" Cauchoix (the largest refractor of the early 1830s) A.A. Commons reflectors (later reworked into Crossley and Harvard telescopes) Lassel's reflector, this 24-inch metal mirror telescope was used to discover the moons Triton and Hyperion. Newton's reflector 40-foot telescope (England) Armagh Observatory 15-inch Grubb reflecting telescope. Specula metal mirror mounted on an equatorial, with clockwork-drive. Bedford Observatory Tully 5.9-inch refractor (8.5 feet focal length); Dollond mount with Sheepshanks clockwork drive. Cambridge Observatory 36-inch (3 feet = 91.44 cm) aperture reflector
Observations A noted accomplishment of the biggest telescope at the time, Ross's "six foot" leviathan, was the observation of the spiral structure of M51, which was presented at Cambridge in the summer of 1845. Herschel was also quite prolific discovering a planet and many moons of the Solar system with his reflectors.
See also Lists of telescopes List of telescopes of Australia David Dunlap Observatory (Largest telescope of the British Empire in the 1930s)
References
External links The 98 inch (249 cm) mirror glass of original INT