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)
Yevpatoria RT-70 radio telescope Yevpatoria RT-70 radio telescope The Yevpatoria RT-70 radio telescope (P-2500, RT-70) is an RT-70 radio telescope and planetary radar at the Center for Deep Space Communications, Yevpatoria, Crimea. In the scientific literature is often called Evpatoria Planetary Radar (EPR). With its 70-meter antenna diameter, it is among the largest single dish radio telescopes in the world. It has an advantage in comparison with other large radio telescopes in the fact that the complex includes powerful transmitters that allow active space experiments. Powerful electromagnetic beams can be accurately targeted and the signals received can be analyzed. For this reason, the Yevpatoria