A 4-m reflector for solar studies being built at an altitude of 3050 m at Haleakala Observatory, Hawaii, by a consortium of over 20 US institutions led by the National Solar Observatory. Using adaptive optics it will be able to resolve features on the Sun as small as 30 km across at wavelengths from the near ultraviolet to the infrared (0.3–35 μ‎m). When opened in 2019, it will be the largest solar telescope in the world. It is named after Daniel K. Inouye, former US Senator from Hawaii.

http://www.nso.edu/telescopes/dki-solar-telescope/ Official telescope website.