CARA Science:
Site Characterization


Over the past few years, careful measurements at the South Pole have shown that conditions there are exceptionally good for certain kinds of astronomy. The advantages of Antarctic sites over those at temperate locations stem principally from the extreme cold and dryness, combined with the high altitude and the stability of the atmosphere (Harper 1989; Burton et al. 1994).

The most unique and important characteristic of the site is the extreme stability of the atmospheric opacity. This stability has been understood anecdotally for years as CARA telescopes demonstrated it was possible to chop over large angles (10 degrees) for CMB observations and to integrate for long periods to achieve extremely sensitive spectra at submillimeter wavelengths and not be limited by the atmosphere. The low opacity at submillimeter wavelengths has been quantified by several instruments, including a NRAO 225 GHz tipping radiometer (Chamberlin and Bally 1994) and daily submillimeter tipping curves with the AST/RO telescope (Chamberlin et al. 1997). Recently, the stability has been quantified by careful analyses of Python CMB anisotropy data (Lay & Halverson 1999) and of data from a dedicated tipping radiometer at = 350 microns obtained in collaboration with NRAO.

* A Brief Atlas of Atmospheric Characteristics
* Comparison with Other Sites
* The Bottom Line: Site Characterization Statistics: The South Pole is the best ground based site known for projects requiring imaging over large angular scales, large area surveys, or extremely high sensitivity at thermal infrared through millimeter wavelengths.

Information by atmospheric characteristic: Information by wavelength:

Information by instrument: