Nordic Optical Telescope (NOT). Time-exposure image of star trails over the dome of the 2.6- metre NOT at the Roque de los Muchachos observatory on La Palma in the Canary Islands. This telescope observes at optical and infrared wavelengths. Its 11.1-metre diameter dome stands at an altitude of 2382 metres, making it the highest telescope on La Palma. The NOT is jointly operated by institutions in Denmark, Finland, Norway and Sweden. The observatory is an ideal site because the high altitude and the clear air above it mean that atmospheric distortions to incoming light are minimised.