Dome A in Antarctica Is the Best Site for Optical Astronomical Observation on Earth

The site for astronomy at Dome A.
Credit: SHANG Zhaohui

A research team led by Prof. SHANG Zhaohui from National Astronomical Observatories of the Chinese Academy of Sciences (NAOC) has proved that Dome A in Antarctica is the best site for optical astronomical observation on Earth. The study was published in Nature.

Seeing reflects the atmospheric turbulence that makes stars twinkle or smears star images observed by telescopes. At an observatory with good seeing, weak turbulence results in a smaller seeing value and sharper images. This is especially good for viewing faint objects. A small-aperture telescope at such a site can compete with a larger one at other sites.

Due to the geographic and atmospheric properties at Dome A, atmosphere turbulence usually resides in the near-ground, shallow boundary layer, above which is the very stable free atmosphere with superb seeing.

The researchers reported a seeing measurement as good as 0.13 arcseconds and a median free-atmosphere seeing of 0.31 arcseconds, measured with instruments on an 8-m-high tower.

Currently, the best telescopes are located at good sites in Hawaii and Northern Chile, with seeing in the range of 0.6 to 0.8 arcseconds. It is clear that Dome A has the potential to host a good astronomical observatory.

In addition, the median boundary layer thickness is about 14m at Dome A, compared to 30m at Dome C in Antarctica, making Dome A more feasible and cost-efficient for future construction.

Dome A is the highest place on the polar ice cap, with an altitude of 4093m. Kunlun Station is the only station there, but has not yet been developed into a winterover station. Therefore, the team had to design and build unattended instruments to cope with temperatures as low as -80? and frosting problems.

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