William Herschel Telescope

The William Herschel Telescope or WHT was first conceived in the late 1960s, when the Anglo-Australian Observatory was being designed. The British astronomical community saw the need for telescopes of comparable power in the Northern Hemisphere. Planning began in 1974, but by 1979 the project was on the verge of being scrapped due to a ballooning budget. A re-design cut the price-tag substantially, and Dutch astronomers took a 20% stake in the project, allowing the project to be given the go-ahead in 1981. 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. The telescope is a member of the Isaac Newton Group of Telescopes.


William Herschel Telescope outside
Construction began in 1983, and the telescope was shipped to La Palma in 1985. It saw first light in 1987. The telescope has an altazimuth mount. The mirror is maintained so that its theoretical maximum resolution is less than 0.2 arcseconds. The typical seeing at La Palma is of the order of one arcsecond, so the telescope is limited by that.
As a competitive research telescope, the WHT is heavily oversubscribed, and typically three times more applications for telescope time are received than can be accommodated. Notable discoveries made using the WHT include that of a hot bubble of expanding gas at the centre of our galaxy, suggestive of the presence of a supermassive black hole; the first observation of the optical counterpart of a gamma-ray burst; and recently, the discovery of a Wolf-Rayet star with the fastest-known stellar wind.


Contemporaries on commissioning

The William Herschel Telescope was about the third or fourth largest optical telescope at its first light in 1987. The MMT Observatory, commissioned in 1979 had six 1.8 m mirrors for about 6 m aperture or 4.7 m equivalent collecting area. They were both very new, very large telescopes for western astronomers in the 1980s.
Large optical ground telescopes in 1987:
# Name /
Observatory Image Aperture M1
Area Altitude First
Light Note
1 BTA-6
Special Astrophysical Obs 238 inch
605 cm 26 m² 2070 m
(6791 ft) 1975 CCCP
2 Hale Telescope
Palomar Obs. 200 inch
508 cm m² 1713 m
(5620 ft) 1949 California, United States
Multiple Mirror Telescope
Fred Lawrence Whipple Obs. 1.8 m x 6
4.7 m equiv. m² 2617 m
(8585 ft) 1979 Multi-mirror design 1979-1998
William Hershel Telescope
ORM Observatoy 165 inch
420 cm 13.8 m² 2396 m
(7,860 ft) 1987 3rd largest single aperture
4 Mayall Telescope
Kitt Peak National Obs. 158 inch
401 cm 12 m² 2120 m
(6955 ft) 1973
5 Blanco Telescope
CTIO Obs. 158 inch
401 cm 12 m² 2200 m
(7217 ft) 1976 Southern Hemisphere
6 Anglo-Australian Telescope
Siding Spring Obs. 153 inch
389 cm 12 m² 1742 m
(5715 ft) 1974 Southern Hemisphere
Source:wikipedia