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)
McMath–Pierce solar telescope the organization that operates Kitt Peak National Observatory on behalf of the NSF. McMath–Pierce solar telescope McMath–Pierce solar telescope is a 1.6 m f/54 reflecting solar telescope at Kitt Peak National Observatory in Arizona, United States. The building was designed by Myron Goldsmith and built in 1962. It is the largest solar telescope and the largest unobstructed aperture telescope in the world. It is named for astronomers Robert McMath and Keith Pierce. The telescope is a triple instrument. In addition to the primary 1.61 m mirror fed by the 2.03 m heliostat, there are a pair of telescopes fed by