Big, bigger, biggest

Posted by Daniel Pendick
on Tuesday, May 22, 2007

The Giant Magellan Telescope (GMT), with a planned light-gathering surface 24.5 meters (80.3 feet) across, has a rival to the title of "biggest proposed telescope in Chile." Pieces of the GMT are under construction, and it's generally assumed the telescope will be constructed at Las Campanas Observatory in Chile's Atacama Desert.

Now, a consortium led by Cornell University and Caltech says it will build a 25-meter instrument in the same Atacama region of Chile, with its exceptionally dry and steady seeing. The Cornell Caltech Atacama Telescope (CCAT) will cost an estimated $100 million.

CCAT will best the GMT by a whopping half meter! C'mon, guys, why didn't you just pop for, say, 2 or 3 more meters? How much more could it cost? Beating out the GMT by a half meter is like winning the "highest building in the world" title by building a taller radio antenna on the top floor.

A Cornell press release claims the CCAT will be "the largest, most precise and highest astronomical facility in the world." That's great news, because bigger and higher count for a lot in astronomy. Bigger means you can collect more photons of light, and, therefore, see fainter objects. Higher is better, because less atmosphere to look through means sharper images.

CCAT may not wear the crown for long. Telescopes with light-gathering surfaces 30, 50, and even 100 meters have been proposed. You can read all about it in "How big will telescopes get?" by astronomer Christina Dunn in the July 2007 issue of Astronomy.

Telescope-makers appear to at least have a sense of humor about their bigger-is-better profession. The working name of the proposed 100-meter instrument: the OverWhelmingly Large (OWL) Telescope.

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