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)
IRAM 30m telescope from the Solar System to interstellar dust and gas or cosmology. Formally started in 1980 and in use for astronomical observations beginning in 1984, the observatory features a radio telescope produced by MT Mechantronics with a pedestal-yoke design. The 30m telescope is one of the largest and most sensitive millimeter telescopes in the world, and is equipped with a suite of heterodyne receivers and continuum cameras operating at wavelengths of around 3, 2, 1, and 0.9mm. IRAM offers guided tours through the observatory and public talks during the summer months. IRAM 30m telescope The IRAM 30m millimeter radio telescope is