Concept
The XO Project is an international team of amateur and professional astronomers tasked with identifying extrasolar planets. They are led by Peter R. McCullough of the Space Telescope Science Institute. It is primarily funded by NASA's Origins Program and the Director's Discretionary Fund of the Space Telescope Science Institute. Preliminary identification of possible star candidates starts at the Haleakala telescope in Hawaii by a team of professional astronomers. Once they identify a star that dims slightly from time to time (the transit method), the information is forwarded to a team of amateur astronomers who then investigate for additional evidence suggesting this dimming is caused by a transiting planet. Once enough data is collected, it is forwarded to the University of Texas McDonald Observatory to confirm the presence of a transiting planet by a second team of professional astronomers. McCullough and his team employed a relatively inexpensive telescope called the XO Telescope, made from commercial equipment, to search for extrasolar planets. The construction of the one-of-a-kind telescope cost $60,000 for the hardware, and much more than that for the associated software. The telescope consists of two 200-millimeter telephoto camera lenses, and resembles binoculars in shape. It is similar to the TrES survey telescope. It stands on the summit of the Haleakalā volcano and 3,054 m (10,000 foot) in Hawaii. Their first discovery of a Jupiter-sized planet orbiting a Sun-like star 600 light-years from Earth in the constellation Corona Borealis—XO-1b—was reported May 16, 2006 on Newswise. In 2016 three similar double telescopes were operating, two in Spain and one in Utah. The XO telescope has discovered six objects so far, five are hot Jupiter planets and one, XO-3b, may be a brown dwarf.