Photographers take multiple shots to reduce the chance that pictures will be marred by blinking or grimacing subjects. Now astronomers are applying the same technique to improve images of distant objects.
Images of the Cat's Eye Nebula taken with the 200-inch telescope at Palomar Observatory. On the top is a conventional image, and on the bottom is one produced using the "lucky imaging technique".
Scientists at the University of Cambridge and California Institute of Technology have developed a "lucky imaging" technique that takes large numbers of pictures to get around the problem that Earth's atmosphere degrades image quality. That technique relies on a high-speed camera that takes as many as 20 images per second, then on a computer that sifts out the sharpest and combines them into a final view.
"These are the sharpest images ever taken either from the ground or from space," lead researcher Craig Mackay of the University of Cambridge's Institute of Astronomy said in a statement.
The technique has produced sharper images than those in space and is vastly less expensive. The 200-inch Hale Telescope at Caltech's Palomar Observatory, built in the 1940s, ordinarily produces images 10 times less detailed than those of the Hubble Space Telescope. But the lucky camera produces double the resolution -- combined with existing technology called adaptive optics that compensates for some atmospheric distortion, the researchers said.
The technique will work on larger, more modern telescopes such as those at the European Southern Observatory in Chile and the Keck telescopes in Hawaii. "The low cost means that we could apply the process to telescopes all over the world," Mackay said.
Adaptive optics works well for infrared light, but the Hubble beats out the Palomar telescope for light visible to humans. The lucky imaging system produces better material for the adaptive optics system to work with, the researchers said, with the result that the Palomar telescope comes out ahead.
Lucky imaging has been around as a concept since the 1970s, but it's only been possible now through the development of a new generation of image sensors that combine high sensitivity with low electronic "noise" that degrades the image with spurious speckles. The Cambridge-Caltech team used a sensor made by E2V Technologies, the researchers said.
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