World biggest telescope to be built in central Chile

The Giant Magellan Telescope will be built in central Chile, it has been announced.

London, Oct 5 : The Giant Magellan Telescope will be built in central Chile, it has been announced.

After considering various sites in northern Chile, astronomers decided to build the GMT in central Chile at the mountainside site of Las Campanas Observatory, the existing home of the twin 6.5-metre Magellan Telescopes.

The observatory is located in the Atacama Desert and boasts of dry climate, dark skies and a stable atmosphere - all key conditions for making good astronomical observations.

"Excellent science has come from Las Campanas for several decades. The superb astronomical quality of the site is a significant contributor to this success," said Wendy Freedman, head of the GMT Board and director of the Carnegie Observatories, which operates Las Campanas.

The GMT will be completed in 2016 and use seven 8.4-metre mirrors arranged into a 'super dish'. One mirror will be at the centre and six curved around it like petals.

Such "off-axis" mirrors have never been made as large as this. Scientists say the design would make the telescope's vision keener than it would be if all seven mirrors remained separate. The GMT will produce images up to 10 times as sharp as the Hubble Space Telescope, said Freedman.

The telescope will have an effective aperture of 24.5 metres, much larger than the twin 10-metre Keck telescopes in Hawaii, US, which are currently the world's largest optical telescopes.

"We hope to have four of the . . . mirrors in the telescope mount by the year 2013, at which time this would be the world's largest telescope," said Freedman, adding that the GMT is scheduled to be finished by 2016.

The GMT's first mirror - made from 18 tonnes of borosilicate glass made from sand gathered in Florida, US - was cast at the University of Arizona's famed Mirror Laboratory in 2005.

It is now being polished - a painstaking process that is likely to take until 2009. pon completion, its surface will be extremely smooth, containing bumps or dips no taller than 25 nanometres.

Arnold Phifer, director of external affairs at the Carnegie Observatories, said, scientists decided to build one of the six off-axis mirrors first, since they - unlike the central mirror - cannot be perfectly symmetric in their concavity.

"The six are higher and thicker on the outside [of the super dish] and narrower and thinner on the inside. We wanted to prove to the astronomical community and potential funders that we're sure we know all the parameters of [how to build it]," said Phifer.

Charles Alcock, director of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, US, a member of the GMT consortium, said the telescope will usher in "a new age of astronomical exploration".

"As telescopes get larger, we are able to see fainter, farther and with more clarity than ever before," New Scientist magazine quoted Alcock as saying.

He said astronomers planned to study extrasolar planetary systems, the formation of stars, galaxies and black holes and the nature of dark matter and dark energy with the telescope.

ANI