California Extremely Large Telescope

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The California Extremely Large Telescope (CELT) was a proposal for an extremely large telescope design first proposed in the 1990s by a consortium of Californian Universities.[1] The design was for a segmented 30 m diameter astronomical telescope. The CELT had a positive reception and continued to be developed,[2] and was renamed The Thirty Meter Telescope around 2003-4. The CELT was one of the earlier and more successful proposals for Extremely large telescopes.

The optical design for CELT is a Ritchey-Chretien two-mirror system, with a segmented mirror mosaic with 1080 segments.[2] This rather naturally provides a large, 20 arcminute field of view with less than 0.5 arcsecond images (100% enclosed energy). This focus is free of coma and only suffers from astigmatism, which grows quadratically with field angle. The primary will be 30 metres (98 ft) in diameter, and for compactness, the primary f-ratio will be f/1.5. The final focus will be f/15, delivering a final focus with about 2 mm/arcsecond as its plate scale. Such a giant telescope produces very large seeing-limited images, a challenge for the design of seeing-limited scientific instruments. The 20 arcminute field is 2.6 metres (8.5 ft) in diameter.

See also[edit]


  1. ^ Irion, R (8 November 2002). "California Astronomers Eye 30-Meter Scope". Science 298 (5596): 1151–1153. doi:10.1126/science.298.5596.1151. PMID 12424344. 
  2. ^ a b "UC Santa Cruz astronomers forge ahead on giant telescope project". UC Santa Cruz. September 6, 2000. Retrieved 2009-03-10. 

External links[edit]

  • CELT website (archived)