Submillimeter Array

Event Horizon Telescope Smithsonian Astrophysical Observatory Radio telescope
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Submillimeter Array
Smithsonian Submillimeter Array.jpg
The Submillimeter Array
Part ofEvent Horizon Telescope
Mauna Kea Observatories Edit this on Wikidata
Location(s)Hawaii County, Hawaii
Coordinates19°49′27″N 155°28′41″W / 19.8243°N 155.478°W / 19.8243; -155.478Coordinates: 19°49′27″N 155°28′41″W / 19.8243°N 155.478°W / 19.8243; -155.478 Edit this at Wikidata
OrganizationAcademia Sinica
Smithsonian Astrophysical Observatory Edit this on Wikidata
Altitude4,080 m (13,390 ft) Edit this at Wikidata
Wavelength0.717 mm (418 GHz)-1.67 mm (180 GHz)
Telescope styleradio interferometer Edit this on Wikidata
Number of telescopesEdit this on Wikidata
Diameter6 m (19 ft 8 in) Edit this at Wikidata Edit this at Wikidata
Submillimeter Array is located in Hawaii
Submillimeter Array
Location of Submillimeter Array
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The Submillimeter Array (SMA) consists of eight 6-meter (20 ft) diameter radio telescopes arranged as an interferometer for submillimeter wavelength observations. It is the first purpose-built submillimeter interferometer, constructed after successful interferometry experiments using the pre-existing 15-meter (49 ft) James Clerk Maxwell Telescope and 10.4-meter (34.1 ft) Caltech Submillimeter Observatory as an interferometer. All three of these observatories are located at Mauna Kea Observatory on Mauna Kea, Hawaii, and can be operated together as a ten element interferometer in the 230 and 345 GHz bands (eSMA, for extended Submillimeter Array). The baseline lengths presently in use range from 16 to 508 meters (52 to 1,667 ft), and up to 783 meters (2,569 ft) for eSMA operations. The radio frequencies accessible to this telescope range from 180–418 gigahertz (1.666–0.717 mm) which includes rotational transitions of dozens of molecular species as well as continuum emission from interstellar dust grains. Although the array is capable of operating both day and night, most of the observations take place at nighttime when the atmospheric phase stability is best.

The SMA is jointly operated by the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics.

Science with the SMA

The SMA is a multi-purpose instrument which can be used to observe diverse celestial phenomena. The SMA excels at observations of dust and gas with temperatures only a few tens of kelvins above absolute zero. Objects with such temperatures typically emit the bulk of their radiation at wavelengths between a few hundred micrometers and a few millimeters, which is the wavelength range in which the SMA can observe. Commonly observed classes of objects include star-forming molecular clouds in our own and other galaxies, highly redshifted galaxies, evolved stars, and the Galactic Center. Occasionally, bodies in the Solar System, such as planets, asteroids, comets and moons, are observed.

The SMA has been used to discover that Pluto is 10 K (18 °F) cooler than expected.[1] It was the first radio telescope to resolve Pluto and Charon as separate objects.[2]

The SMA is a part of the Event Horizon Telescope, which observes nearby supermassive black holes with an angular resolution comparable to the size of the object's event horizon.


See also


  1. ^ "A planet colder than it should be". 2006-01-03. Retrieved 2008-11-25.
  2. ^ Gurwell, Mark A; Butler, Bryan J (August 2005). "Sub-Arcsecond Scale Imaging of the Pluto/Charon Binary System at 1.4 mm". Bulletin of the American Astronomical Society. 37: 743. Bibcode:2005DPS....37.5501G.