Astronomical seeing at the South Pole

A Hartmann differential image motion monitor (H-DIMM) was used on two different telescopes situated at the South Pole to measure astronomical seeing. A series of observations conducted 12 m above the surface during two Austral winters indicates that the median "ground level" seeing at 500 nm was similar to 1.7 arcseconds. This is in good agreement with microthermal measurements from balloon flights which indicate that the seeing is dominated by a temperature inversion which appears within the first 220 m above the surface during the winter. Above this layer, the mean "free atmosphere" seeing is 0.37 +/- 0.07 arcseconds.