Astronomy at Dome C, Antarctica
75° 06' S - 123° 20' E - 3300 m| Dome C is located on the Antarctic
plateau more than 1000 km away of the Antarctic coast. High altitude, low
wind speed, clear weather, coronal sky, dry air, no pollution... and the
presence of the Franco-Italian Concordia station : Dome C may be the best
accessible astronomical site on Earth ! |
Eric Fossat and his group at South Pole
in 1979
|
Astronomy on the Antarctic plateau began
in 1979 when Eric Fossat, Gérard Grec (Nice University) and Martin
Pomerantz installed the first heliosismologic observatory at South Pole.
For six consecutive days with no interruption, their instrument observed the sun and recorded its oscillations. They resolved the well known 5mn-period oscillation and obtained the first power spectrum showing the individual frequencies of solar p-modes. A new science was born, called heliosismology. And it was born in Antarctica. The Nice group returned 3 times at South Pole to observe solar oscillations, last time was in1984. |
| In 1994, J. Vernin and R. Marks conducted
a program of turbulence probing of the atmosphere above the South Pole.
They launched radiosound helium balloons equipped with microthermal sensors
allowing to measure the vertical profile of the turbulence up to 30km. Seeing is not good at South Pole (recent mesurements by the group of J. Storey, UNSW, Sydney, found an average velue of 1.7 arcsec). That is due to almost permanent catabatic winds blowing from the higher plateau (in particular from Dome A). However, Vernin and Marks found that major part of the turbulence was concentrated into the first hundred meters above ground. Seeing would fall to 0.3 arcsec 300m above the South Pole. |
Wind map of Antarctica.
Click to enlarge. |
|
There was another site on the Antarctic
plateau where the French and Italian polar institutes intended to built
a permanent base. This base would be the third on the plateau (after the
South Pole and Vostok base). It was located near the top of Dome Charlie
(so no problem of catabatic winds) and 400m higher than the South Pole. In 1995, a franco-italian group directed by J. Vernin launched the same stratospheric balloons at Dome C to measure the turbulence profile. This was the begining of the adventure ! The very promising qualities of the site and the started construction of the Concordia station encouraged the Nice group to initiate a detailed analysis of the astronomical site properties, under the name of Concordiastro, first funded by IPEV in 2000. |