William Herschel Telescope - History

History

The WHT was first conceived in the late 1960s, when the 3.9 m (150 in) 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 1.0 m (39 in) (which became the Jacobus Kapteyn Telescope), the 2.5 m (98 in) Isaac Newton Telescope which was to be moved from its existing site at Herstmonceux Castle, and a 4m class telescope, initially planned as a 4.5 m (180 in). A new site was chosen at an altitude of 2,344 m (7,690 ft) 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 4.2 m (170 in). 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 £36M in 2012); within budget once inflation is taken into account.