History of the telescope a wider field of view than a classic Cassegrain. During the period 1850–1900, reflectors suffered from problems with speculum metal mirrors, and a considerable number of "Great Refractors" were built from 60 cm to 1 metre aperture, culminating in the Yerkes Observatory refractor in 1897; however, starting from the early 1900s a series of ever-larger reflectors with glass mirrors were built, including the Mount Wilson 60-inch (1.5 metre), the 100-inch (2.5 metre) Hooker Telescope (1917) and the 200-inch (5 metre) Hale telescope (1948); essentially all major research telescopes since 1900 have been reflectors. A number of 4-metre class (160 inch)
United Kingdom Infrared Telescope United Kingdom Infrared Telescope UKIRT, the United Kingdom Infra-Red Telescope, is a 3.8 metre (150 inch) infrared reflecting telescope, the second largest dedicated infrared (1 to 30 micrometres) telescope in the world. Until 2014 it was operated by the Joint Astronomy Centre in Hilo and located on Mauna Kea, Hawai'i as part of Mauna Kea Observatory. It was owned by the United Kingdom Science and Technology Facilities Council. UKIRT is currently being funded by NASA and operated under scientific cooperation between Lockheed Martin Advanced Technology Center, the University of Hawaii, and the U. S. Naval Observatory. The telescope is set