From the South Pole, microthermal turbulence within a narrow surface boundary layer some 200 m thick provides the dominant contribution to the astronomical seeing. We present results for the seeing at a wavelength of 2.4 mum. The narrow turbulence layer above the site, confined close to the surface, provides greatly superior conditions for adaptive optics correction than do temperate latitude sites. An analysis of the available meteorological data for the Antarctic plateau suggests that sites on its summit, such as Domes A and C, probably experience significantly better boundary layer seeing than does the South Pole. In addition, the inversion layers may be significantly narrower, lending the sites even further to adaptive optics correction than does the Pole.

We have used the SPIREX telescope to conduct a wide-field thermal infrared imaging study of the star formation complex NGC 6334 in the southern Galactic plane. We imaged a 30' region along the main star-forming ridge of NGC 6334 with 0."6 pixel scale through broadband filters for L (3.5 mum) and M (4.8 mum) and through narrowband filters for the H-2 nu = 1-0 Q-branch (2.42 mum), polycyclic aromatic hydrocarbon (PAH) (3.3 mum), and Br alpha (4.05 mum) lines. The images reveal the spectacular, complex structure of the photodissociation regions (PDRs) that pervade the region, with enhanced line emission around each of the seven sites of massive star formation along the ridge. Bubbles and loops of PAH emission, typically 1-1.5 pc across, have been carved out of the parent molecular cloud by the intense UV radiation from the massive stars and surround H II regions (seen in Br alpha) typically 0.2-0.3 pc across. The PAH emission regions coincide with both [C II] 158 mum line emission, indicating that the PAHs are excited in PDR gas, and extensive H-2 emission, which therefore must be fluorescent. However, the textures of the emission regions in PAH and H-2 are different. This is attributable to variations in the physical environment in which the gas is excited. Several compact reddened objects are observed; these are likely to be massive protostars.

Results from the 1995 season of site-testing experiments at the South Pole are presented, in which the seeing was measured using balloon-borne microthermal probes. Our analysis shows a marked division of the atmosphere into two characteristic regions: (i) a highly turbulent boundary layer (0 - 220 m) associated with a strong temperature inversion and wind shear, and (ii) a very stable free atmosphere. The mean seeing, averaged over 15 balloon flights, was measured to be 1.86 ", of which the free atmosphere component was only 0.37 ". The seeing from similar to 200 m upward is superior to the leading mid-latitude sites (e.g. Fuchs 1995; Roddier et al. 1990) by almost a factor of two. The results are in good agreement with optical seeing data obtained by a differential image motion monitor on three of the five occasions when the two measurements were performed simultaneously. The boundary layer winds are of katabatic origin, and so we may consider the possibility of exceptional seeing conditions from surface level at other locations on the plateau such as Domes A and C, where there is little or no katabatic wind. In addition, the proximity of the optical turbulence to the focus of a telescope situated at ground level is a highly favourable situation for the use of adaptive optics, since the wavefront spatial coherence scale is related to the altitude of the turbulent layers producing the image distortion. Some comparisons are made between the relevant adaptive optics parameters measured at the South Pole and Cerro Paranal, one of the best mid-latitude sites.

ABU is a NOAO IR imaging camera designed for evaluating the performance of the 1024x1024 Aladdth InSb array. For this experiment, it was outfitted with five filters (see Figure 9) m the 3-5 micron range to exploit the low water vapor and lower air temperatures at the South Pole. At the South Pole it was integrated with the CARA SPIREX (South Pole Infrared Explorer) telescope. Figure 1 is a picture of the telescope showing the environmental box (the white box by the author). which protected ABU and its electronics from ambient environmental conditions.

Results from experiments measuring the optical seeing in the surface layer at the South Pole Station are presented. Seeing measurements were taken over 49 data runs between April and August 1994, using microthermal sensors placed at 3 levels on a 27 m-high mast. The seeing contribution from this region was quite large in comparison with similar experiments performed at other sites, with a mean value measured over this period of 0:64 00 . However, there is often a signicant decrease in the optical turbulence over the height of the mast, with mean values of 0:37 00 and 0:46 00 measured in the upper (17 27 m) and lower (7 17 m) sections respectively. These measurements coincide with a large and highly variable temperature inversion, the behaviour of which is often well correlated with the observed turbulence prole. The results can be roughly separated into four or ve categories, characterised by the temperature inversion alone. Further analysis of the data should provide some predictive power about the likely optical turbulence prole of the surface layer in given observing conditions.