Stargazing Great Canary Telescope - First Light

[Astronuc]

TENERIFE, Canary Islands (AP) - One of the world's largest and most powerful telescopes opened its shutters, turned its 34-foot wide mirror toward the skies and captured its first light at a mountaintop on one of Spain's Canary Islands on Saturday.

The $179 million Great Canary Telescope, designed to take advantage of pristine, clear skies at the Roque de los Muchachos observatory atop the Atlantic island of La Palma, should be fully operational by May 2008.

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[Testing began with] 12 of the telescope's eventual 36 mirrors aimed at a twin star close to the Earth's northern axis, near the North Star. Twelve images merged into one as the telescope focused.
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The GCT is among the world's largest telescopes like the newly opened Southern African Large Telescope — Salt — which has a 36-foot mirror and has been described the southern hemisphere's largest single optical telescope and the Hobby-Eberly telescope on Mount Fowlkes, Texas, which also has an 36-foot mirror.
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AP News

Tests begin on Canaries telescope
http://news.bbc.co.uk/2/hi/science/nature/6897293.stm

 

[mgb_phys]

The GCT is a clone of the Keck and uses the same 36 hexagon mirrors with essentially no gaps between them to give a mirror approx 10m diameter, it is fractionally larger than the keck for allegedly engineering reasons to do with a different mirror polisher but probably to claim the largest title!
Having said that the 4x8m mirrors of the VLT can be combined to be larger.

Salt and Hobberly-Eberly don't really count in the same way - they are made up of spherical mirror segments and cannot form a (high quality) image - both are used as light buckets for spectrographs only. They also cannot point fully as most optical telescopes but have a feed which tracks across a small region of the sky while the telescope is fixed, a little like an optical Arecibo.

Although La Palma isn't as high or dry as Mauna Kea and so as an infrared site it isn;t as good the 'seeing' or atmospheric distortion is often better and is a much more pleasant place to work because of the lower altitude - although the food isn't as good as on Hawaii!