The XO Telescope is a telescope

Telescope

A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation . The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s , using glass lenses...

 located on the 3,054 m summit of Haleakala

Haleakala

Haleakalā , or the East Maui Volcano, is a massive shield volcano that forms more than 75% of the Hawaiian Island of Maui. The western 25% of the island is formed by the West Maui Mountains.- History :...

 on Maui

Maui

The island of Maui is the second-largest of the Hawaiian Islands at and is the 17th largest island in the United States. Maui is part of the state of Hawaii and is the largest of Maui County's four islands, bigger than Lānai, Kahoolawe, and Molokai. In 2010, Maui had a population of 144,444,...

, Hawaii

Hawaii

Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...

, formed by a pair of 200 mm telephoto lens

Telephoto lens

In photography and cinematography, a telephoto lens is a specific type of a long-focus lens in which the physical length of the lens is shorter than the focal length. This is achieved by incorporating a special lens group known as a telephoto group that extends the light path to create a long-focus...

es. It is used to detect extrasolar planets using the transit method. It is similar to the TrES

Tres

The tres is a 3-course, 6-string chordophone which was created in Cuba. A tres player is called a tresero in Cuba and a tresista in Puerto Rico.-Cuban tres:In Cuba, the son was created as a song and a salon dance genre...

 survey telescope. The construction of the one-of-a-kind telescope cost $60,000 for the hardware, and much more than that for the associated software.

Planets discovered

The XO telescope has discovered five objects so far, four are hot Jupiter

Hot Jupiter

Hot Jupiters are a class of extrasolar planet whose mass is close to or exceeds that of Jupiter...

 planets and one, XO-3b

XO-3b

XO-3b is an exoplanet with about 11.79 times the mass of Jupiter, and an orbit around its parent star in about 3.2 days. The radius of this object is 1.217 times that of Jupiter. Astronomers announced their discovery on May 30, 2007, at the American Astronomical Society in Honolulu, Hawaii...

, is probably a brown dwarf

Brown dwarf

Brown dwarfs are sub-stellar objects which are too low in mass to sustain hydrogen-1 fusion reactions in their cores, which is characteristic of stars on the main sequence. Brown dwarfs have fully convective surfaces and interiors, with no chemical differentiation by depth...

. All were discovered using the transit method.

Star Star A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...	Constellation Constellation In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....	Right ascension Right ascension Right ascension is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. The other coordinate is the declination.-Explanation:...	Declination Declination In astronomy, declination is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. Declination in astronomy is comparable to geographic latitude, but projected onto the celestial sphere. Declination is measured in degrees north and...	App. mag. Apparent magnitude The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...	Distance (ly)	Spectral type Stellar classification In astronomy, stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure...	Planet Planet A planet is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.The term planet is ancient, with ties to history, science,...	Mass Mass Mass can be defined as a quantitive measure of the resistance an object has to change in its velocity.In physics, mass commonly refers to any of the following three properties of matter, which have been shown experimentally to be equivalent:... (MJ Jupiter mass Jupiter mass , is the unit of mass equal to the total mass of the planet Jupiter . Jupiter mass is used to describe masses of the gas giants, such as the outer planets and extrasolar planets. It is also used in describing brown dwarfs.... )	Radius Radius In classical geometry, a radius of a circle or sphere is any line segment from its center to its perimeter. By extension, the radius of a circle or sphere is the length of any such segment, which is half the diameter. If the object does not have an obvious center, the term may refer to its... (RJ)	Orbital period Orbital period The orbital period is the time taken for a given object to make one complete orbit about another object.When mentioned without further qualification in astronomy this refers to the sidereal period of an astronomical object, which is calculated with respect to the stars.There are several kinds of... (d Day A day is a unit of time, commonly defined as an interval equal to 24 hours. It also can mean that portion of the full day during which a location is illuminated by the light of the sun... )	Semimajor axis (AU Astronomical unit An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance.... )	Orbital eccentricity	Inclination Inclination Inclination in general is the angle between a reference plane and another plane or axis of direction.-Orbits:The inclination is one of the six orbital parameters describing the shape and orientation of a celestial orbit... (° Degree (angle) A degree , usually denoted by ° , is a measurement of plane angle, representing 1⁄360 of a full rotation; one degree is equivalent to π/180 radians... )	Discovery year
XO-1 XO-1 XO-1 is a magnitude 11 yellow dwarf star located approximately 600 light-years away in the constellation Corona Borealis. XO-1 has a mass and radius similar to the Sun...	Corona Borealis Corona Borealis Corona Borealis is a small constellation in the northern sky. Its name is Latin for "northern crown", a name inspired by its shape; its main stars form a semicircular arc. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy and remains one of the 88 modern...			11.319	600	G1V	XO-1b XO-1b XO-1b is an extrasolar planet approximately 600 light-years away in the constellation of Corona Borealis. The planet was discovered orbiting the yellow dwarf star now designated XO-1 in 2006.- Discovery :...	0.9	1.3	3.941534	0.0488	0	87.7	2006
XO-2 XO-2 XO-2 may refer to:*XO-2b - An extrasolar planet orbiting the star XO-2 in the constellation Lynx*XO-2 - A star with exoplanet XO-2b in orbit around it*OLPC XO-2 - A design study of the One Laptop per Child computer...	Lynx Lynx (constellation) Lynx is a constellation in the northern sky, introduced in the 17th century by Johannes Hevelius. It is named after the lynx, a genus of cat. It is a very faint constellation; its brightest stars form a zigzag line.-History:...			11.25	486	K0V	XO-2b XO-2b XO-2b is an extrasolar planet orbiting the star XO-2 in the constellation Lynx. This planet was found by transit method in 2007 by Burke et al...	0.57	0.973	2.615838	0.0369	0	88.58	2007
XO-3 XO-3 XO-3 is a star in the constellation Camelopardalis. The star has a magnitude of 10 and is not visible to the naked eye but is visible through a small telescope.-Planetary system:...	Camelopardalis Camelopardalis Camelopardalis is a large but faint constellation in the northern sky. The constellation was introduced in 1612 by Petrus Plancius. Some older astronomy books give an alternative spelling of the name, Camelopardus.-Etymology:...			9.91	850	F5V	XO-3b XO-3b XO-3b is an exoplanet with about 11.79 times the mass of Jupiter, and an orbit around its parent star in about 3.2 days. The radius of this object is 1.217 times that of Jupiter. Astronomers announced their discovery on May 30, 2007, at the American Astronomical Society in Honolulu, Hawaii...	11.79	1.217	3.1915239	0.0454	0.26	84.2	2007
XO-4 XO-4 XO-4 is a star located approximately 956 light-years away from Earth in the Lynx constellation. It has a magnitude of about 11 and cannot be seen with the naked eye but is visible through a small telescope.-Planetary system:...	Lynx Lynx (constellation) Lynx is a constellation in the northern sky, introduced in the 17th century by Johannes Hevelius. It is named after the lynx, a genus of cat. It is a very faint constellation; its brightest stars form a zigzag line.-History:...			10.78	956	F5V	XO-4b XO-4b XO-4b is an extrasolar planet approximately 956 light years away in the constellation of Lynx. This planet was found by the transit method by McCullough in May 2008. The planet has mass 1.72 MJ and radius 1.34 RJ...	1.72	1.34	4.12502	0.0555	0.0024	88.7	2008
XO-5 XO-5 XO-5 is a yellow dwarf main sequence star located approximately 830 light-years away from Earth in the Lynx constellation. It has a magnitude of about 12 and cannot be seen with the naked eye but is visible through a small telescope.-Planetary system:...	Lynx Lynx (constellation) Lynx is a constellation in the northern sky, introduced in the 17th century by Johannes Hevelius. It is named after the lynx, a genus of cat. It is a very faint constellation; its brightest stars form a zigzag line.-History:...			12.1	881	G8V	XO-5b XO-5b XO-5b is an extrasolar planet approximately 831 light years away in the constellation of Lynx. This planet was found by the transit method by Burke et al. in May 2008. The planet has mass 1.15 MJ and radius 1.15 RJ, making the density of this planet identical to water...	1.15	1.15	4.187732	0.0508	0.0029	86.8	2008

See also

• List of extrasolar planets

A subset of XO light curves are available at the NASA Star and Exoplanet Database

NASA Star and Exoplanet Database

The NASA Star and Exoplanet Database is an on-line astronomical stellar and exoplanet catalog and data service that collates and cross-correlates astronomical data and information on exoplanets and their host stars. NStED is dedicated to collecting and serving important public data sets involved...

.

Other Ground Transit Surveys

• Trans-Atlantic Exoplanet Survey
  Trans-Atlantic Exoplanet Survey
  The Trans-atlantic Exoplanet Survey or TrES, uses three 4-inch telescopes located at Lowell Observatory, Palomar Observatory, and the Canary Islands to locate exoplanets. It was made using the network of small, relatively inexpensive telescopes designed to look specifically for planets orbiting...
  
   or TrES
• HATNet Project
  HATNet Project
  The Hungarian Automated Telescope Network project is a network of six small fully automated "HAT" telescopes. The scientific goal of the project is to detect and characterize extrasolar planets using the transit method. This network is used also to find and follow bright variable stars...
  
  or HAT

External links

• The XO Project website
• Astronomers Catch Planet By Unusual Means (SpaceDaily) May 19, 2006