Wide-Field Astronomy from Antarctica

Today’s workshop concerned wide-field astronomy done from a recent Chinese installation called AST-3 at Dome A in Antarctica. Three Chinese scientists (one of whom, Lifan Wang, I knew from my days in the supernova group at LBL) told about fifty Australian scientists from all over the country about the work they’d been doing on AST-3. The University of New South Wales (UNSW) already has an astronomy program called PLATO-A installed at Dome A. This workshop was in part about discussing opportunities for Chinese and Australian astronomers to collaborate on projects involving AST-3 and future telescopes planned for the Dome A site.

While it might not be your favorite holiday spot even in the austral summer, there are plenty of good reasons to do optical astronomy in Antarctica. Most of them have to do with the observing conditions: Dome A is about 13,000 feet (4 km) above sea level, and the winter air is among the driest and most stable on earth. There is very little wind, no dust or pollution, and if you put your telescope on a tower about 20 m in height, you’ll be above the “boundary layer” where the churning of thermal currents in the atmosphere limits the sharpness of your images. The “seeing”, a measure of the smallest detail you can see in your images, at visible wavelengths is about 0.2 arcseconds median at Dome A, or about twice as sharp as Mauna Kea; on a good night you can get images as sharp as with the Hubble Space Telescope! And for about six months of the year you get continual night, instead of the sun getting in the way right when your variable object is doing something really interesting.

The instrument design for AST-3 is also interesting: the camera has no shutter. The detector is divided into an “active” region in the middle, and two “holding” region on the sides; when the camera is done exposing, the charge is pushed off to the sides and read out while a new exposure is taking place. Done this way, the telescope never has to stop observing to read out the data, and there is no chance of a mechanical shutter failure (which happens from time to time on cameras that do have shutters). This kind of setup is ideal for constant monitoring of variable sources which change brightness significantly over very short time intervals (minutes).

The main science opportunities identified by the group include: supernovae (particularly shock breakouts, which last from minutes to days); transiting exoplanets and asteroseismology (like Kepler, but on the ground); and “time-variable extragalactic sources” (blazars?). While no firm agreements have yet been made, in the next month or two there working groups of Chinese and Australian scientists will probably be formed to start getting into the specifics of the science to be done. There is also the more prosaic business of forging partnerships with industry, government, and external sources of funding to build new infrastructure and observing capabilities at Dome A to support these science projects. While the AST-3 telescopes are very small (0.5 m), future projects may include a 2.5-m or even a large 8-m class telescope.

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About Richard

I'm an American scientist who is building a new life in Australia. This space will contain words about science and math, but also philosophy, policy, literature, my travels, occasional rants, all sorts of things I find strange and awesome. The views expressed in this blog do not necessarily reflect the opinions of my employer at the time (currently University of Sydney), though personally, I think they should.
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