 This 4.3-meter reflecting telescope is the fifth-largest telescope in the contiguous United States and one of the most powerful in the world, thanks to a unique housing that can accommodate up to five instruments at the Ritchey-Chrétien focus.The LDT can switch between any of these instruments in about a minute, making it uniquely suited for time-domain programs as well as opportunity targets such as gamma ray bursts and supernovae.The 6700-pound primary mirror measures in diameter yet only about in thickness.