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)
Telescope Array Project and data processing center for the Telescope Array Project. In October 2011, a new visitor center was opened at the Cosmic Ray Center. It features displays about the history of cosmic ray research in Utah and about the Telescope Array, which is spread across the desert west of Delta. The center also includes a display about the nearby Topaz internment camp, where U.S. citizens of Japanese descent were imprisoned during World War II. TALE is the Telescope Array Low Energy extension. It is designed to observe cosmic rays with energies between 3×10eV and 10eV. TALE adds 10 new telescopes to