A 268-megapixel camera is showing astronomers some of faintest objects and widest angles ever photographed, catching events they otherwise might miss.
The OmegaCAM is part of the VLT Survey Telescope, at the European Southern Observtory in Paranal, Chile. Most telescopes geared to faint objects are focused on a narrow piece of the sky, measured in minutes of arc, or sixtieths of a degree. A small telescope often has a wider field of view, but then it's harder to see fainter objects, such as small galaxies. The OmegaCAM has a field of a square degree, or about twice the diameter of the Moon.
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The pixels in the camera, meanwhile, have a resolution of 0.2 seconds of arc, about .00005 degrees. If the telescope were on the moon it could pick out structures on Earth the size of a typical shopping mall or large buildings like the Pentagon. The actual resolution from Earth is less, about 0.7 arcseconds, because of the planet's atmosphere.
These images have a lot of information in them. Each one is a gigabyte's worth, and requires a dedicated fiber optic connection to the observatory from the ESO's headquarters in the suburbs of Munich. With several images taken every night and observations made 300 nights a year, the data approaches the terabyte range.
Getting that wide field is important if astronomers want to see what happens to galaxies at various stages in their life cycles, and get a better view of galaxy clusters. Collisions of smaller galaxies, or the way galaxies on the edge of a cluster behave, are particular areas of interest.
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Sometimes spiral galaxies are disrupted as they collide with their cousins in a cluster, and scientists want ot know how those interactions play out. But even though a collision between two galaxies takes millions of years, before something like the OmegaCAM existed, finding them took a long time.
"Interesting things happen to galaxies on the outskirts," said Gijs Verdoes Kleijn, an astronomer also at the University of Groningen. "But was too expensive to survey these areas. Galaxies spend a relatively short time in transition phase and you are looking at a large area of sky, so the chance of catching them is low."
"That's why the Hercules supercluster image is so outstanding," said Edwin Valentijn, professor of astronomical information technology at the University of Groningen. "It's a large scale structure in the sky. The core is 10 square degrees."
Photos: the star-forming region Messier 17, also known as the Omega Nebula or the Swan Nebula in the constellation of Sagittarius (top); the Omega-CAM camera (left).
Credit: ESO / INAF-VST / OmegaCAM
