The Two Micron All-Sky Survey, or 2MASS, was an

astronomical survey An astronomical survey is a general celestial cartography, map or astrophotography, image of a region of the sky (or of the whole sky) that lacks a specific observational target. Alternatively, an astronomical survey may comprise a set of image ...

of the whole sky in

infrared Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...

light. It took place between 1997 and 2001, in two different locations: at the U.S.

Fred Lawrence Whipple Observatory The Fred Lawrence Whipple Observatory is an American astronomical observatory owned and operated by the Smithsonian Astrophysical Observatory (SAO); it is their largest field installation outside of their main site in Cambridge, Massachusetts. ...

on Mount Hopkins, Arizona, and at the Cerro Tololo Inter-American Observatory in Chile, each using a 1.3-meter telescope for the Northern and Southern Hemisphere, respectively. It was conducted in the short-wavelength infrared at three distinct

frequency band Spectral bands are regions of a given spectrum, having a specific range of wavelengths or frequencies. Most often, it refers to electromagnetic bands, regions of the electromagnetic spectrum. More generally, spectral bands may also be means in ...

s ( J, H, and K) near 2

micrometre The micrometre (English in the Commonwealth of Nations, Commonwealth English as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American English), also commonly known by the non-SI term micron, is a uni ...

s, from which the photometric survey with its

HgCdTe Hg1−''x''Cd''x''Te or mercury cadmium telluride (also cadmium mercury telluride, MCT, MerCad Telluride, MerCadTel, MerCaT or CMT) is a chemical compound of cadmium telluride (CdTe) and mercury telluride (HgTe) with a tunable bandgap spanning th ...

detectors derives its name. 2MASS produced an

astronomical catalog An astronomical catalogue is a list or tabulation of astronomical objects, typically grouped together because they share a common type, Galaxy morphological classification, morphology, origin, means of detection, or method of discovery. The olde ...

with over 300 million observed objects, including

minor planet According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''minor ...

s of the Solar System,

brown dwarf Brown dwarfs are substellar objects that have more mass than the biggest gas giant planets, but less than the least massive main sequence, main-sequence stars. Their mass is approximately 13 to 80 Jupiter mass, times that of Jupiter ()not big en ...

s, low-mass stars,

nebula A nebula (; or nebulas) is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral, or molecular hydrogen and also cosmic dust. Nebulae are often star-forming regions, such as in the Pillars of Creation in ...

star cluster A star cluster is a group of stars held together by self-gravitation. Two main types of star clusters can be distinguished: globular clusters, tight groups of ten thousand to millions of old stars which are gravitationally bound; and open cluster ...

s and

galaxies A galaxy is a system of stars, stellar remnants, interstellar gas, dust, and dark matter bound together by gravity. The word is derived from the Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar Sys ...

. In addition, 1 million objects were cataloged in the ''2MASS Extended Source Catalog'' (''2MASX''). The cataloged objects are designated with a "2MASS" and "2MASX"-prefix respectively.

Catalog

The final data release for 2MASS occurred in 2003, and is served by the Infrared Science Archive. The goals of this survey included: * Detection of galaxies in the " Zone of Avoidance", a strip of sky obscured in visible light by our own galaxy, the

Milky Way The Milky Way or Milky Way Galaxy is the galaxy that includes the Solar System, with the name describing the #Appearance, galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars in other arms of the galax ...

. * Detection of brown dwarfs. 2MASS discovered a total of 173, including 2MASS 0939-2448, 2MASS 0415-0935, 2M1207, and 2MASS J04414489+2301513. * An extensive survey of low mass stars, the most common type of star both in our own galaxy and others. * Cataloging of all detected stars and galaxies. * Infrared measurements from the 2MASS survey have been particularly effective at unveiling previously undiscovered star clusters.Froebrich, D.; Scholz, A.; Raftery, C. L. (2007)
''A systematic survey for infrared star clusters with , b, <20° using 2MASS''
MNRAS, 347, 2Majaess, D. (2013)
''Discovering protostars and their host clusters via WISE''
ApSS, 344, 1 Numerical descriptions of point sources (

star A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sk ...

planet A planet is a large, Hydrostatic equilibrium, rounded Astronomical object, astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. The Solar System has eight planets b ...

asteroid An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...

s) and extended sources (galaxies, nebulae) were cataloged by automated computer programs to an average limiting

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

of about 14. More than 300 million

point source A point source is a single identifiable ''localized'' source of something. A point source has a negligible extent, distinguishing it from other source geometries. Sources are called point sources because, in mathematical modeling, these sources ...

s and 1 million extended sources were cataloged. In November 2003, a team of scientists announced the discovery of the

Canis Major Dwarf Galaxy The Canis Major Overdensity (''CMa Overdensity'') or Canis Major Dwarf Galaxy (''CMa Dwarf'') is a disputed dwarf irregular galaxy in the Local Group, located in the same part of the sky as the constellation Canis Major. The supposed small gal ...

, at that time the closest known satellite galaxy to the Milky Way, based on analysis of 2MASS stellar data. The resulting data and images from the survey are currently in the

public domain The public domain (PD) consists of all the creative work to which no Exclusive exclusive intellectual property rights apply. Those rights may have expired, been forfeited, expressly Waiver, waived, or may be inapplicable. Because no one holds ...

, and may be accessed online for free by anyone. There is also a list of 2MASS science publications with links to free pre-publication copies of the papers. 2MASS is sponsored by the

University of Massachusetts Amherst The University of Massachusetts Amherst (UMass Amherst) is a public land-grant research university in Amherst, Massachusetts, United States. It is the flagship campus of the University of Massachusetts system and was founded in 1863 as the ...

, the

Infrared Processing and Analysis Center The Infrared Processing and Analysis Center (IPAC) provides science operations, data management, data archives and community support for astronomy and planetary science missions. IPAC has a historical emphasis on infrared-submillimeter astronomy a ...

(IPAC, run by

Jet Propulsion Laboratory The Jet Propulsion Laboratory (JPL) is a Federally funded research and development centers, federally funded research and development center (FFRDC) in La Cañada Flintridge, California, Crescenta Valley, United States. Founded in 1936 by Cali ...

(JPL) and

Caltech The California Institute of Technology (branded as Caltech) is a private university, private research university in Pasadena, California, United States. The university is responsible for many modern scientific advancements and is among a small g ...

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

, and the

National Science Foundation The U.S. National Science Foundation (NSF) is an Independent agencies of the United States government#Examples of independent agencies, independent agency of the Federal government of the United States, United States federal government that su ...

(NSF).

References

External links

2MASS at IPAC

2MASS All-Sky Release Database
* {{Portal bar, Astronomy, Stars, Outer space * Astronomical catalogues Astronomical surveys Photometric systems