Astronomers Find World’s Best Observing Site

by Brian Ventrudo on August 31, 2009

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Image of the Chinese Kunlun base, near "Ridge A"

Image of the Chinese Kunlun base, near "Ridge A"

The search for the best observatory site in the world has lead to the discovery of what is thought to be the coldest, driest, calmest place on Earth. No human is thought to have ever been there, but it’s expected to yield images of the heavens three times sharper than any ever taken from the ground.

The joint US-Australian research team combined data from satellites, ground stations and climate models to assess the many factors that affect the quality of an observing site – cloud cover, temperature, sky-brightness, water vapour, wind speeds and atmospheric turbulence.

The researchers pinpointed a site on an Antarctic plateau with the prosaic name “Ridge A”.  At an elevation of 4,053 m, the ridge is not only remote but extremely cold and dry. The study revealed that Ridge A has an average winter temperature of -70 °C, and that the water content of the entire atmosphere in a vertical column above the ridge is equivalent to a layer of liquid water less than the thickness of a human hair.

The ridge is also extremely calm, which means that there is very little of the atmospheric turbulence elsewhere that makes stars appear to twinkle. “It’s so calm that there’s almost no wind or weather there at all,” says Dr. Will Saunders of the Anglo-Australian Observatory and visiting professor to the University of New South Wales, who led the study.

“The astronomical images taken at Ridge A should be at least three times sharper than at the best sites currently used by astronomers,” says Dr. Saunders. “Because the sky there is so much darker and drier, it means that a modestly-sized telescope there would be as powerful as the largest telescopes anywhere else on earth.”

They found that the best place in almost all respects was not the highest point on the Plateau – called Dome A – but 150km away along a flat ridge.

“Ridge A looks to be significantly better than elsewhere on the Antarctic plateau and far superior to the best existing observatories on high mountain tops in Hawaii and Chile,” says Dr. Saunders.

Ridge A is located within the Australian Antarctic Territory (81.5 °S 73.5 ºE), the site is 144km from an international robotic observatory and the proposed new Chinese ‘Kunlun’ base at Dome A (80.37 °S 77.53 °E).

Interest in Antarctica as a site for astronomical and space observatories has accelerated since 2004 when astronomers published a paper in the journal Nature confirming that a ground-based telescope at Dome C, another Antarctic plateau site, could take images nearly as good as those from the space-based Hubble telescope.  A detailed study by the Anglo-Australian Observatory suggests the cost of building and running the 2.5 m telescope PILOT optical/infrared telescope at Dome C would be US$8.5 million.

The finding is published today in the Publications of the Astronomical Society of the Pacific.

Source: University of New South Wales

graham August 31, 2009 at 11:58 AM

I think that’s a superb place. It can double as a how-to-survive-on-Mars research station too.

Silver Thread August 31, 2009 at 12:01 PM

I might be difficult to make observations of Polaris from this area, but it has the potential to double as a Mars Research Outpost since the climate may be similar, certain it will be remote enough to feel like another planet.

ILOVETHESTAR August 31, 2009 at 1:18 PM

Nice place for a 50 meter optical scope–only problem is finding the crew to build it and what the materials will have to be made of in that ‘cool’ place.

MitchyMitch August 31, 2009 at 5:40 PM

What is all that mist doing obscuring the mountain peak?

Astrofiend August 31, 2009 at 5:51 PM

Yeah – either that is a poor choice of accompanying picture, or the site doesn’t look so crash-hot to me. It’s cloudy!

Jon Hanford August 31, 2009 at 6:57 PM

Imagine the integration times possible during the Austral Winter :)

Nexus September 1, 2009 at 12:20 AM

Whoa! Six month exposure times.

Torbjorn Larsson OM September 1, 2009 at 4:19 AM

Someone asked for local materials for telescopes? Can’t think of anything cheaper than ice for your mirrors.

Good training for similar “locally made” telescopes on the Moon too. And perhaps opportunity for a nice synergy with ice detectors, say for neutrinos?

[Of course, plating ice for reflectance without destroying the surface might be a wee bit of a problem.]

Aqua September 1, 2009 at 10:26 AM

I was thinking the same thing when I read the above. I.E. What part of the observatory could be made out of ice?

Spun cast pure water ice… with a ‘sputtered’ mercury coating?

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