Concept for a second giant magellan telescope (GMT) in antarctica

Roger Angel, Jon Lawrence, John Storey

Research output: Contribution to journalConference article

16 Scopus citations

Abstract

While definitive winter measurements for Dome C must await until 2004, on the basis of existing data the Antarctic Dome sites promise the best conditions on the Earth for many astronomical observations. Because atmospheric turbulence is largely confined to a ∼ 100 m ground layer, adaptive correction with a single deformable mirror conjugated to this layer should yield an 8-arcminute field of view with 0.1 arcsec images at optical wavelengths. The ground layer wavefront aberration can likely be sensed with natural guide stars found over the wide field. In the infrared there is the added advantage of low thermal background from the cold atmosphere and telescope optics, as much as 50x reduction in the 3.5 μm L band. An ELT that fully exploited these advantages would provide a uniquely powerful ground-based complement to the James Webb Space Telescope, especially for spectroscopy. We consider here the concept of building a copy of the 21m Giant Magellan telescope (GMT) telescope (Johns, 2003) at Dome C. The optical design is ideal, with a very fast (f/0.7) primary mirror and direct Gregorian focus formed by a deformable secondary conjugated to the ground layer. In the thermal infrared, diffraction-limited images are produced with the low background of only two warm mirrors, the primary and secondary. There are also practical advantages. The enclosure is of modest size, by ELT standards, because the primary is very fast. Assembly, debugging and maintenance problems on-site are minimized by a primary mirror built from a small number of large, pre-tested segments. By building a copy of an already implemented ELT, engineering difficulties will be minimized, and experienced support staff will be available at the first GMT, where also instruments can be pre-tested.

Original languageEnglish (US)
Pages (from-to)76-84
Number of pages9
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume5382
Issue numberPART 1
DOIs
StatePublished - Oct 25 2004
EventSecond Backaskog Workshop on Extremely Large Telescopes - Backaskog Castle, Sweden
Duration: Sep 9 2003Sep 11 2003

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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