2013A&A...554L...5O

Dome Fuji, the second highest region on the Antarctic plateau, is expected to have some of the best astronomical seeing on Earth. However, site testing at Dome Fuji is still in its very early stages. We investigate the astronomical seeing in the free atmosphere above Dome Fuji and determine the height of the surface boundary layer. A Differential Image Motion Monitor was used to measure the seeing in the visible (472nm) at a height of 11 m above the snow surface at Dome Fuji during the austral summer of 2012/2013. Seeing below 0.2" has been observed. The seeing often has a local minimum of ∼0.3" near 18 h local time. Some periods of excellent seeing, 0.3" or smaller, were also observed, sometimes extending for several hours around local midnight. The median seeing is larger, at 0.52". This high value is believed to be caused by periods when the telescope was within the turbulent boundary layer. The diurnal variation in the daytime seeing at Dome Fuji is similar to what is reported for Dome C, and the height of the surface boundary layer is consistent with previous simulations for Dome Fuji. The free atmosphere seeing is ∼0.2", and the height of the surface boundary layer can be as low as ∼11m.