119 The National Solar Observatory
The main telescope at NSO Sacramento Peak is the Richard B. Dunn Solar Telescope. This imposing solar tower, 136 feet high, produces 0.2 arc-second resolution and over many years has produced some of the finest solar images and data. Another 220 feet of the Dunn Solar Telescope lies below ground, making the total length of this imposing instrument 356 feet. The instrument was upgraded to include adaptive optics; another advantage to reduce seeing effects while observing the sun.