Because of the remarkable clarity, dryness, and stillness of the air, and its elevation (with atmospheric pressure of 71 kPa/533 mm Hg), as well as the absence of the lights of major cities, the summit of Haleakalā (like Mauna Kea) is one of the most sought-after locations in the world for ground-based telescopes. As a result of the geographic importance of this observational...