The Hubble Space
Telescope may take photos of the universe's deepest reaches, but some ground
telescopes may now get a "Lucky" leg-up on image clarity.
Using the
new "Lucky Imaging" system, a team of astronomers claims to have
taken pictures of stars twice
as sharp as those produced by Hubble.
"These are
the sharpest images ever taken either from the ground or from space," said
Craig Mackay, an astronomer at the University of Cambridge in England who led the research.
Mackay and
his colleagues' findings are presented on the Web site for the Institute of Astronomy at the University of Cambridge.
Twinkle stopper
Earth's
fluctuating atmosphere not only causes stars to
twinkle, but also blurs the photos of astronomers trying to snap clear
images of the cosmos.
Sensitive
cameras can beat the blurriness, but they produce grainy "noise" that
can make images nearly unusable. On the other hand, space telescopes such as
the Hubble avoid the problem by orbiting above Earth's atmosphere altogether,
yet they carry billion-dollar price tags.
To create a
ground-based system that could beat noise and fit a budget, Mackay and his team
used power in numbers. Their new imaging system takes pictures at 20 frames per
second, chooses the best of tens of thousands of images, merges them together
and eliminates random noise.
"To produce
images sharper than Hubble from the ground is a remarkable achievement by
anyone's standards," Mackay said of the system, adding that its estimated
cost of about $100,000--less than a hundredth of a percent of the Hubble space
telescope's growing
price tag--is an even greater achievement.
Telescope
test
The
astronomers tested the Lucky Imaging system with a 200-inch (5.1-meter)
telescope at the Palomar Observatory in San Diego, Calif. The observatory
normally produces images 10 times less detailed than Hubble's, but the new
camera created images twice as sharp as those of the space telescope.
Mackay
explained that the performance boost came from comparing
two images of the globular star cluster M13.
"The
star cluster image already shows we can exceed Hubble's clarity, but we think
we can do much better," Mackay told SPACE.com. The astronomer
noted, however, that Hubble has a better ability to take longer exposures and
produce "deeper" views of the cosmos.
Mackay thinks
the new imaging system's most effective use will be in larger telescopes, where
it can be used to expand the search for mysterious
dark matter.
"The images
space telescopes produce are of extremely high quality, but they are limited to
the size of the telescope," Mackay said. "Our techniques can do very well when
the telescope is bigger than Hubble and has intrinsically better resolution."
The one
catch for Mackay's new system: Clear conditions and plenty of time are required
to produce crisp images that exceed Hubble's abilities.
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