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ToSeek
2004-Sep-15, 08:59 PM
Starry nights clearest in Antarctica (http://www.newscientist.com/news/news.jsp?id=ns99996405)


The images obtained from the astronomy test station at Dome C, 75 south and 3260 metres above sea level, were up to three times sharper and six times brighter than those from the best mid-latitude observatories, including those in Hawaii and Chile. On some nights, the images were almost as good as those from the Hubble Space Telescope.

This must be what all those astronomers who have moved to Antarctica are working on. ;)

Q&A about the project. (http://www.phys.unsw.edu.au/nature/) There were a few technical issues (http://www.phys.unsw.edu.au/nature/#45) to deal with:


# The ambient temperature at Dome C reaches a low of -85C during winter. Computers, and electronics in general, are not designed to operate at these temperatures. We took two approaches:

1. With ICECAM we had no reserves of power for heating, so we buried the computer in a crypt seven meters below the ice surface, at which point the temperature is stable at the yearly average of -57C. This is still outside the computer's specification. Fortunately, a test in a low-temperature fridge showed that the computer and solid-state disks worked reliably at these temperatures. ICECAM's camera, a Watec 902-HS, had to remain outside, and tests shows that it was able to operate flawlessly down to at least -80C.
2. With the AASTINO, the stirling engines produced up to 6 kW of waste heat, which we utilized to maintain a comfortable operating temperature of about -10C.

tuffel999
2004-Sep-15, 09:55 PM
This must be what all those astronomers who have moved to Antarctica are working on. ;)


No way. There isn't a mass conspiracy down there.....egads......my world is torn asunder. :o

Ut
2004-Sep-15, 10:10 PM
I always figured they were down there so that, when they pole flip occured, they'd be closer to home when it was all said and done.

(Ok, I admit, while this makes sense to me, and is really funny as a groaner, anyone who tries to make any sense of it will probably find it a wee bit subtle -- and I don't do subtle very well.)

Russ
2004-Sep-16, 12:29 AM
Those folks are flat crazy. I've been up to Prudo Bay in Alaska during the winter. OOOOOOOOOOOOOOOOOWWWWWWWWWWWWwEEEEEEEEEEEE it's cold up there!!!!

One thing I'm not sure about. When I was on the slope, there was always aurora going on, non-stop. Do they not have that problem down south? I'd figure that it'd be a PITA to have an auroral wave blot out your picture of Eta Carina at the last second. :roll: #-o

ToSeek
2004-Sep-16, 01:21 AM
Those folks are flat crazy. I've been up to Prudo Bay in Alaska during the winter. OOOOOOOOOOOOOOOOOWWWWWWWWWWWWwEEEEEEEEEEEE it's cold up there!!!!



The observations are all automatic - I think they say somewhere that none of them have actually seen a sunset in Antarctica because they do all their work during the Antarctic summer.

ngc3314
2004-Sep-16, 01:30 AM
By the way - this resut is a major big deal because the image quality for previous instruments at the south pole station itself has been disappointing. There was some evidence that this was a very local effect near the ground, but it is tough to build a tall enough structure there to be sure. Dome C is, IIRC, at a higher elevation above the plateau and thus a promising place to improve the seeing...

polytropos
2004-Sep-16, 03:42 AM
Might not be too popular with astronomers who have to pay for their own travel, however. Getting to and from the interior of the continent can be time consuming, if not worse. Even with telescopes becoming more automated, I don't know of any that can function without support for as long as this one would be required to.

On the other hand, half arcsecond and better seeing without adaptive optics is pretty impressive. Limited number of targets, though. Wonder what the actual latitude is at that site: not useful for much, but a curiosity.

chiaroscuro25
2004-Sep-16, 05:06 AM
Limited number of targets, though.No more limited than any other place on the face of the Earth. No matter where you are, you see about half the sky.

AK
2004-Sep-16, 12:25 PM
Extremely dry air is another factor that seems like it would contribute to the good seeing, though I didn't see it explicitly mentioned. Lots of good reasons to build a scope down there. There's little to no lightning, not much dust, no seismic activity of any appreciable magnitude, weeks without daylight in the winter make constant observation possible, etc.


Wonder what the actual latitude is at that site: not useful for much, but a curiosity.

According to the link: The latitude of Dome C is 75 06'S, the longitude 123 23'E.

frogesque
2004-Sep-16, 12:41 PM
As well as the elevation of the site, is the atmosphere actually thinner at the poles (due to Earth's rotation) or does it make no significant difference? Another factor could be ozone depletion which would give better viewing in UV bands.

I think for the cost of a Hubble replacement or repair mission, the same $$ or invested at the S. Polar site would produce exceptional results. Remote operation, relative safety for maintenace, upgradeable and pretty pictures to boot. WTG! =D>

badprof
2004-Sep-16, 01:50 PM
No more limited than any other place on the face of the Earth. No matter where you are, you see about half the sky.

Not really. Consider if you were at the equator. Then you would be able to see the entire sky. (Although not all at once! :D )

Done near the pole you can only see between declination -90* to just slightly north of 0*. ie only half the sky.

Cheers

Maurice

chiaroscuro25
2004-Sep-16, 03:26 PM
Not really. Consider if you were at the equator. Then you would be able to see the entire sky. (Although not all at once! :D )I was only thinking about what you could see at one point in time. :oops: #-o You're right of course, over the course of a year an equitorial viewer would be able to see everything.

frogesque
2004-Sep-16, 04:05 PM
A polar site is nice though, during winter it's possible to get very long exposures if the sky is clear. True, the viewing horizon is limited but faint objects could be examined in in great detail. Planetary systems on other Sol like stars is one obvious cadidate. Pity there isn't a comparable site near the North Pole!

Let's go for broke and build an array!

rleyland
2004-Sep-16, 10:08 PM
A polar site is nice though, during winter it's possible to get very long exposures if the sky is clear. True, the viewing horizon is limited but faint objects could be examined in in great detail. Planetary systems on other Sol like stars is one obvious cadidate. Pity there isn't a comparable site near the North Pole!

Let's go for broke and build an array!

Hmmm.

Tromso -- Norway
Barrow -- Alaska
Queen Elizabeth Is -- Canada
Svalbard -- Norway?

maybe in the interior of Greenland, for that large landmass...

I guess altitude is the issue really.

Robbo

Ut
2004-Sep-16, 10:18 PM
A huge advantage to Antarctica is the fact that no one lives there. It's cold, clear, and light pollution free.

2004-Sep-16, 10:36 PM
No more limited than any other place on the face of the Earth. No matter where you are, you see about half the sky.

Not really. Consider if you were at the equator. Then you would be able to see the entire sky. (Although not all at once! :D )

Done near the pole you can only see between declination -90* to just slightly north of 0*. ie only half the sky.

Cheers

Maurice

Is that you MC? Another limitation is the relatively short observing season. At Pole it is really dark for only about 4.5 months per year minus the 1/2 of that time the moon is up.

JPO

pghnative
2004-Sep-17, 06:31 AM
...Another limitation is the relatively short observing season. At Pole it is really dark for only about 4.5 months per year minus the 1/2 of that time the moon is up.


Isn't the amount of darkness and "moon-ness" pretty much the same, averaged over the whole year, no matter where you live?

2004-Sep-17, 10:00 AM
...Another limitation is the relatively short observing season. At Pole it is really dark for only about 4.5 months per year minus the 1/2 of that time the moon is up.


Isn't the amount of darkness and "moon-ness" pretty much the same, averaged over the whole year, no matter where you live?

Yes but if you are thinking of long term monitoring of objects then the 12 hours on/12 hours off of more conventional sites is transformed to 4.5 months on/ 7.5 months off at Pole with interspresed 2 weeks dark/2 weeks moonlit. I was lucky enough to have helped build and operate the first nightime automated scope to operate at the South Pole. It did turn out that much more important was that the predicted long periods of cloud free sky did not materialize at Pole (we seldom went more that 24-30 hours without clouds). It appears that Dome C is better although I am not sure that IceCam has proved that yet.

sarongsong
2006-Dec-29, 08:32 AM
Busy area:
Webcasts Coming Up
South Pole Telescope
Date: 12/29/2006
10:00 a.m. PST
As the new [10-meter] telescope reaches completion, the scientists at the South Pole will discuss what they are looking for...
San Francisco Exploratorium (http://www.exploratorium.edu/poles/telescope.php)

ArgoNavis
2006-Dec-29, 11:37 AM
Somewhat more detail is available here:

http://www.phys.unsw.edu.au/nature/

Doodler
2006-Dec-29, 02:15 PM
Getting to and from the interior of the continent can be time consuming, if not worse.

Yeah, I would generally consider "fatal" to be somewhat worse than time consuming. ;)

George
2007-Jan-04, 02:55 PM
How can they claim to gain a 2 magnitude advantage? The atmosphere is not that opaque, at least in the visible portion of the spectrum.

StupendousMan
2007-Jan-04, 04:05 PM
How can they claim to gain a 2 magnitude advantage? The atmosphere is not that opaque, at least in the visible portion of the spectrum.

If one is looking at very faint sources, so that the noise in the background in the limiting factor, then the crucial factor is the amount of background sky included in one's measurement; that depends on the angular size of the source. If the seeing at Dome C is 2.5 times better than at an ordinary site -- meaning that the FWHM is 2.5 times smaller at Dome C -- then one can use an aperture which is (2.5*2.5) = 6 times smaller in area to collect the light from the source. This smaller aperture includes only 1/6 of the background sky which falls into the aperture of the ordinary site. If that background sky is the largest source of noise, then you've just cut your noise by a factor of 6 while keeping the signal from your source the same. Voila! A difference of about 2 magnitudes.

George
2007-Jan-04, 05:57 PM
Ah yes, thanks. So I can think of it as a useable, or effective, magnitude gain. If they compare to mid-lattitude scopes that have adaptive optics, however, then the gain would not be as great, I presume.

pghnative
2007-Jan-04, 06:07 PM
<mindless off topic aside>

Heh --- I didn't realize that this thread had been bumped, and when I got to post 17 (by yours truly), I thought, "hey, I didn't post to this thread. Someone has logged in under my account!?!?!"

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