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Science Forum Index » Astro - Seti Forum » $20,000 camera coupled to a 60-year-old telescope
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| Matt Giwer |
 Posted: Mon Sep 17, 2007 11:23 pm |
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MSNBC - Newsweek Technology & Science
9-13-2007
A Heavenly View
New and relatively cheap telescope technology is putting the universe into
incredibly sharp focus. Is the Hubble being rendered obsolete?
WEB EXCLUSIVE
By Andrew Murr
Newsweek
Updated: 3:40 p.m. ET Sept. 13, 2007
Sept. 13, 2007 - Can a $20,000 camera coupled to a 60-year-old telescope
shoot sharper images than the $1.5 billion Hubble Space Telescope?
Absolutely, say astronomers from the University of Cambridge and the
California Institute of Technology.
To prove their point they suggest looking at the top of the Mount Palomar
Observatory near San Diego. This summer a team from both universities
grafted their “Lucky imaging†system onto the observatory’s Hale Telescope
and aimed it at M13, a star cluster that’s 25,000 light years away. The
results were much better than they expected. “What we’ve done for the first
time is produce the highest-resolution [images] ever taken--and we took them
from the ground,†says Craig Mackay of Cambridge’s Institute of Astronomy,
who led the team. “We are getting twice the resolution of Hubble.â€
That’s no small task. While the heat and water vapor in the Earth’s
atmosphere make stars seem to sparkle, their blurring effect also severely
limits the image clarity of ground-based telescopes. Eliminate the
atmosphere, and the view from an observatory would be 20 times clearer.
Getting past the atmosphere was the reason space-based telescopes like the
Hubble were created. And for the past 17 years, the images it has produced
have dropped jaws and raised the standard in astronomical imaging.
But then astronomers at Cambridge and Caltech got “Lucky.†To create their
system they made the most of an existing technology, adaptive optics, and
enhanced it with a super-high-speed digital camera that’s capable of
shooting 20 images every second, says Nicholas Law, a Caltech postdoctoral
scholar who worked on the Lucky project.
Adaptive optics is a way of correcting the atmosphere’s distortion of light
as it enters the telescope. A sensor measures the distortion and corrects
most of it using a flexible mirror that shifts the light back into straight
lines. Then the Lucky camera shoots in rapid-fire fashion, and astronomers
select the images that capture moments when atmospheric distortion is
minimal.
“The adaptive optics took out the larger-scale turbulence and let our Lucky
imaging work on what’s left over,†explains Mackay. “Our ‘luck’ improved
greatly."
Amateur astronomers have been using low-grade Lucky imaging for several
years, but the unit used by the Cambridge-Caltech group had an advantage. At
its heart was a tiny charge-coupled device (CCD), from a British company
called e2v Technologies, that can detect individual photons even when the
camera is running at high speeds, while eliminating virtually all the noise
that mars space images.
Lucky may have taken a sharper picture, but no one wants to sell the Hubble
for space scrap. Scheduled for another refurbishment next summer by the
Shuttle crew, Hubble will remain the premier telescope platform at least
until 2013, when it will be joined in space by the James Webb Space
Telescope. (The Shuttle program sunsets in 2010, effectively ending future
repair missions and limiting Hubble’s life span.) For one thing, Hubble’s
optics provide greater detail over a wider angle, while the Lucky camera as
used at Palomar gives ultra-high resolution only for a tiny slice of the sky
at one time.
Ray Villard, news director at the Space Telescope Science Institute in
Baltimore, which runs Hubble’s science programs, points out that Hubble can
perform many tasks Lucky images will never match. “It’s reasonable to say
[the Lucky image of M13] is sharper. The big question is what can you do
with it?â€
Plenty, at least according to the Lucky team. Mackay and Law believe there’s
plenty of work for both Hubble and ground-based telescopes with the Lucky
edge. “Hubble is terribly important,†says Mackay, “and there is no way that
this can replace Hubble.â€
With their success in San Diego, the Cambridge and Caltech teams have their
sights set on even larger observatories. They’re hoping to install Lucky on
the giant 10-meter telescope at the Keck Observatory in Hawaii. With
adequate funding, the researchers can expand the size of the CCD, too. If
all that works, they should stay busy looking at tiny--and incredibly
clear--slivers of the sky for years to come. © 2007 Newsweek, Inc.
--
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without any form of financial reward.
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