Editing Nordic Optical Telescope (section)

{{short description|Astronomical telescope located at Roque de los Muchachos Observatory}}
{{Infobox telescope|locmapin=Spain Canary Islands}}
[[Image:Not inst 2003.jpg|250px|thumb|The interior of the telescope, showing an instrument on the Cassegrain focus.]]
The '''Nordic Optical Telescope''' ('''NOT''') is an astronomical [[telescope]] located at [[Roque de los Muchachos Observatory]], [[La Palma]] in the [[Canary Islands]]. The telescope saw first light in 1988, and was officially inaugurated during September 1989. Regular observing started in 1990.  It is funded by [[Denmark]], [[Sweden]], [[Norway]], [[Finland]], and (since 1997) [[Iceland]]. Access is provided directly to astronomers of the funding countries, and of all nationalities through international time allocation committees.

The main mirror has a diameter of {{convert|2.56|m|in}}. The optical forming was done at the optical laboratory at the [[Tuorla Observatory]], on mirror blanks made of Zerodur at [[Schott AG|Schott]] Glaswerke in Mainz, Germany.<ref>{{Cite web|url=http://www.not.iac.es/telescope/tti/proptxt.html|title=Nordic Optical Telescope}}</ref>

While the NOT was designed as a passive telescope, with the mirror sufficiently thick to keep its shape even without an active feedback loop, its mirror was designed to be suspended on a pneumatic support system.<ref>{{Cite web|url=http://www.not.iac.es/telescope/tti/proptxt.html|title=Nordic Optical Telescope}}</ref> The designers had planned that this and the flexibility of the mirror would allow for the implementation of a so-called active optics system, a feature that was then under development for [[ESO]]'s [[New Technology Telescope]]. In 1992, such an active optics system was installed at the NOT.<ref>{{Cite journal|url=http://articles.adsabs.harvard.edu//full/1992ESOC...42..311A/0000311.000.html|bibcode = 1992ESOC...42..311A|title = Active Optics on the Nordic Optical Telescope|last1 = Andersen|first1 = T.|last2 = Larsen|first2 = O. B.|last3 = Owner-Petersen|first3 = M.|last4 = Steenberg|first4 = K.|journal = European Southern Observatory Conference and Workshop Proceedings|year = 1992|volume = 42|page = 311}}</ref>