Widefield IR astronomy at Dome C

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Widefield IR astronomy at Dome C

• Mark Casali
• European Southern Observatory

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personal forward look

• a pathfinder telescope to prove feasibility and
  performance (2012)
• an eventual "big" facility (2018)

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Why do surveys at Dome C ?

• 0.27"-0.4" free seeing above 30m turbulent
  boundary layer
• very low temperatures reduce thermal background
  by 50
• typical PWV of 0.25 mm

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Why leave Dome C alone?

• 30m boundary layer requires telescope on a tower,
  or low-order AO.
• thermal radiation from sky and telescope still
  way above that of Zodiacal emission
• no evidence of significantly lower airglow
  (especially OH). No gain below 2.2 microns, other
  than seeing.
• limited sky coverage

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Diffuse Background
Kdark 1. from PILOT study
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Conclusion for IR widefield

• There are a number of new widefield IR surveys
  underway or soon starting.
• despite big improvements relative to temperate
  sites, a dome C facility needs an 8m aperture to
  compete with "Spitzer" surveys in the thermal IR
• the biggest gain is in K-dark eg. 2m. K-band. 1
  detectors. Low-order GLAO or free seeing from a
  tower would match VISTA.

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Dome C 8m vs Spitzer at 4.5 um
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Working in K dark

• Filter centred at 2.3 microns.
• 2m telescope is competitive