Adaptive optics sky coverage for dome C telescopes

The unique atmospheric characteristics found at Dome C on the Antarctic plateau offer significant advantages for the operation of adaptive optics systems. An analysis is presented here comparing the performance of adaptive optics systems on telescopes located at Dome C with similar systems located at a mid-latitude site. The large coherence length, wide isoplanatic angle, and long coherence time of the Dome C atmosphere allow an adaptive optics system located there to correct to high order, observe over wide fields and use faint guide stars, resulting in a lower total wavefront error and a significant increase in sky coverage factor than can be achieved at a typical mid-latitude site. While the same performance could in principle be achievable at mid-latitude sites, this would only occur under exceptionally stable atmospheric conditions that are likely to occur on only a few nights per year