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CHARA array

  (Redirected from CHARA interferometer)

The CHARA (Center for High Angular Resolution Astronomy) array is an optical interferometric array, owned by Georgia State University (GSU), and located on Mount Wilson, California. It is the most powerful interferometer in the world.[1]

CHARA array
CHARA 1497.jpg
Alternative namesCHARA Edit this at Wikidata
Location(s)Mount Wilson, California, US
Coordinates34°13′29″N 118°03′26″W / 34.22469°N 118.05712°W / 34.22469; -118.05712Coordinates: 34°13′29″N 118°03′26″W / 34.22469°N 118.05712°W / 34.22469; -118.05712 Edit this at Wikidata
OrganizationGeorgia State University Edit this on Wikidata
Telescope styleoptical telescope Edit this on Wikidata Edit this at Wikidata
CHARA array is located in the United States
CHARA array
Location of CHARA array


CHARA’s six telescopes each have a one-meter diameter mirror to reflect light. They are spread across Mount Wilson to increase the angular resolution of the array. Each of the six telescopes provides a different image, to combine it into one image the light from each telescope is transported through vacuum tubes and fed into a single beam, where they are matched up to within one micron. This process is called interferometry, and allows the array to have the same resolving power as a telescope with a 330-meter mirror, and an angular resolution of 200 micro-arcseconds.[1][2]


In 1984 CHARA was founded, and with financial support from the National Science Foundation (NSF), in 1985 planning for the array began. Construction for the array started on July 13, 1996, and with $6.3 million awarded to GSU by the NSF, and the same amount matched by GSU, going towards the effort. In July 1998, GSU was awarded another $1.5 million by W.M. Keck Foundation, which allowed for a sixth telescope to be added to the previously planned five. With a final gift of $574,000 from David and Lucile Packard Foundation, the funding for the array was completed in October 1998.[3]

After another five years of construction, the CHARA array was completed in 2003. In April of the same year, CHARA was awarded a 3-year grant to support scientific programs at the center, which was renewed in 2006.[3] In 2013 another grant from the NSF worth 3.6 million was given to the Center.[4]

Observatories throughout the world have come to CHARA to test beam combining technology.[5]


On January 15, 2007, the diameter of an exoplanet was measured directly, using CHARA. This was achieved by using the observed angular diameter of the star that the planet orbited, and the already known distance of the star from earth, to get the diameter of the star. With this they could calculate the diameter of the exoplanet when comparing its size to the star when it passed in front of it. This was the first time the diameter of an exoplanet was directly measured, and returned a value slightly different than that obtained from indirect, more conventional methods.[6]

In 2013 CHARA was used to capture images showing the starspots on Zeta Andromedae, a star 181 light years away. This was the first time that images of starspots on stars other than our sun has been taken, and the spots acted differently to those on our sun.[clarification needed][7][8]


CHARA holds annual science meetings where recent advancements in science and technologies relevant to the array are discussed. The center also gives access to the array to the astronomical community using the National Optical Astronomy Observatory peer review system for around 50 nights per year. They also have periodic community workshops.

See alsoEdit

  1. ^ a b "About". Retrieved 2017-10-26.
  2. ^ Hand, Eric (2010-04-07). "Telescope arrays give fine view of stars". Nature News. 464 (7290): 820–821. Bibcode:2010Natur.464..820H. doi:10.1038/464820a.
  3. ^ a b Baron, Fabien. "History of CHARA". Retrieved 2017-10-26.
  4. ^ "CHARA Array awarded $3.9 million to provide telescope access to scientists across the nation". EurekAlert!. Retrieved 2017-10-26.
  5. ^ Leverington, David (2016-11-24). Observatories and Telescopes of Modern Times: Ground-Based Optical and Radio Astronomy Facilities since 1945. Cambridge University Press. ISBN 9781316841815.
  6. ^ "CHARA measures an exoplanet". Retrieved 2017-10-26.
  7. ^ "'Starspot' Images that Give Insight into Early Sun Captured by University's CHARA Telescope Array - News Hub -". News Hub. 2016-05-04. Retrieved 2017-10-26.
  8. ^ "Seeing Stars |". Discover Magazine. Retrieved 2017-10-26.