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The William Herschel Telescope (WHT) is a optical/near-infrared reflecting telescope located at the Observatorio del Roque de los Muchachos on the island of La Palma in the Canary Islands, Spain. The telescope, which is named after William Herschel, is part of the Isaac Newton Group of Telescopes. It is funded by research councils from the United Kingdom, the Netherlands and Spain. At the time of construction in 1987, the WHT was the third largest single optical telescope in the world.〔The BTA-6 (6.0 m) and Hale telescope (5.1 m) were both larger; the Multiple Mirror Telescope also had a larger collecting area but did not have a single primary mirror〕〔〔 It is currently the second largest in Europe,〔The neighbouring Gran Telescopio Canarias (10.4 m) overtook the WHT in 2009 to become the largest in Europe〕 and was the final telescope constructed by Grubb Parsons in their 150-year history. The WHT is equipped with a wide range of instruments operating over the optical and near-infrared regimes. These are used by professional astronomers to conduct a wide range of astronomical research. Astronomers using the telescope discovered the first evidence for a supermassive black hole (Sgr A *) at the centre of the Milky Way, and made the first optical observation of a gamma-ray burst. ==History== The WHT was first conceived in the late 1960s, when the Anglo-Australian Telescope (AAT) was being designed. The British astronomical community saw the need for telescopes of comparable power in the northern hemisphere. In particular, there was a need for optical follow-up of interesting sources in the radio surveys being conducted at the Jodrell Bank and Mullard observatories, both located in the UK.〔 The AAT was completed in 1974, at which point the British Science and Engineering Research Council began planning for a group of three telescopes located in the northern hemisphere (now known as the Isaac Newton Group of Telescopes, ING). The telescopes were to be a (which became the Jacobus Kapteyn Telescope), the Isaac Newton Telescope which was to be moved from its existing site at Herstmonceux Castle, and a 4m class telescope, initially planned as a .〔 A new site was chosen at an altitude of on the island of La Palma in the Canary Islands, that is now the Observatorio del Roque de los Muchachos. The project was led by the Royal Greenwich Observatory (RGO), who also operated the telescopes until control passed to an independent ING when the RGO closed in 1998.〔〔〔 By 1979 the 4 m was on the verge of being scrapped due to a ballooning budget,〔 whilst the aperture had been reduced to . A panel known as the Tiger Team〔 was convened to reduce the cost; a re-design cut the price-tag by 45%. Savings were primarily made by reducing the focal length of the telescope – which allowed the use of a smaller dome – and relocating non-essential functions outside the dome to a simpler (and thus cheaper) rectangular annexe.〔 In the same year, the Isaac Newton Telescope was moved to Roque de los Muchachos Observatory, becoming the first of the Isaac Newton Group of Telescopes. In 1981 the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (Netherlands Organization for Scientific Research, NWO) bought a 20% stake in the project, allowing the WHT to be given the go-ahead. That year was the 200th anniversary of the discovery of Uranus by William Herschel, and it was decided to name the telescope in his honour.〔 Construction of the telescope was by Grubb Parsons, the last telescope that company produced in its 150-year history.〔〔 Work began at their workshop in Newcastle-upon-Tyne in 1983, and the telescope was shipped to La Palma in 1985〔 (the two other telescopes of the Isaac Newton Group began operating in 1984〔). The WHT saw first light on 1 June 1987;〔 it was the third largest optical telescope in the world at the time.〔〔 The total cost of the telescope, including the dome and the full initial suite of instruments, was £15M (in 1984, equivalent to £M in 〔); within budget once inflation is taken into account. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「William Herschel Telescope」の詳細全文を読む スポンサード リンク
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