Giant Magellan Telescope

[Dr Mordrid]

Giant Magellan Telescope

Nine Partners Officially Join Giant Magellan Telescope Project

PRESS RELEASE
Date Released: Friday, February 6, 2009
Source: University of Arizona

Nine astronomical research organizations from the United States, Australia and Korea have signed an official agreement to construct and operate the Giant Magellan Telescope, or GMT, at Las Campanas Observatory in Chile, the Giant Magellan Telescope Corp. announced today.

Seok Jae Park, president of the Korean Astronomy and Space Sciences Institute, on behalf of the Republic of Korea, becomes the ninth partner to sign the founder's agreement at ceremonies held at the Carnegie Observatories in Pasadena, Calif., today.

Other participating partners are the Carnegie Institution for Science, The University of Arizona, Harvard University, the Smithsonian Institution, Texas A & M University, the University of Texas at Austin, Australian National University and Astronomy Australia Limited.

The 25-meter (80-foot) GMT is one of the proposed next-generation extremely large telescopes. The colossal telescope will feature six giant off-axis mirrors around a seventh on-axis mirror produced by innovative mirror-making technologies at UA's Steward Observatory Mirror Laboratory.

When completed around 2019, the GMT will produce images 10 times sharper from its site in northern Chile than the Hubble Space Telescope does from space.

"With the signing of this agreement, we can say the GMT project is well launched," said University of Arizona Regents' professor and Steward Observatory director Peter M. Strittmatter, a member of the GMT Corp. board of directors.

GMT Corp. board chairperson Wendy Freedman, director of Carnegie Observatories, said, "The founder's agreement establishes the framework for the construction and operation of the telescope. The founders group represents an extraordinary team of institutions, each one of which has made important contributions to the development of the most advanced telescopes and instrumentation during the last 100 years. The GMT continues this remarkable legacy."

Strittmatter is principal investigator on the $17 million contract for making the first GMT 8.4-meter (27-foot) off-axis mirror at Steward Observatory's Mirror Lab. An off-axis mirror focuses light at an angle away from its axis, unlike a symmetrical mirror that focuses light along its axis.

No off-axis mirror of this size has been made before.

The Mirror Lab spin-cast the first GMT 20-ton mirror blank in July 2005 and is currently machining its surface to near-final shape.

"One of the greatest technical challenges being tackled at the Mirror Lab is polishing and testing the off-axis mirror to an accuracy of one-millionth of an inch," said Roger Angel, director of the Mirror Lab and director of the Center for Astronomical Adaptive Optics.

Arizona and Italy pioneered another feature which will make the GMT an extremely powerful tool, Strittmatter noted. The GMT will have unique adaptive secondary mirrors that quickly change their shape to correct for air turbulence.

The GMT will be enclosed in a 200-foot high building at the Carnegie Institution's Las Campanas Observatory in the Andes Mountains in Chile.

"In both the mirror technology and the site, the GMT project is building on the superb heritage demonstrated by the two very successful 6.5-meter (21-foot) Magellan telescopes that have been operation at Las Campanas since 2000," said Matt Johns, GMT program manager.

GMT partners plan to complete the detailed design for the telescope over the next two years and begin construction in 2012. The consortium has so far raised $130 million for the $700 million project.

"The science opportunities for this telescope are extraordinary," Carnegie Observatories astronomer and GMT acting director Patrick McCarthy said. "It will shed light not only upon the nature of the universe, but also on the fundamental laws of physics that govern its evolution. As such, it seems especially fitting that this international founder's agreement should have been signed in the International Year of Astronomy, the 400th anniversary of the first astronomical use of a telescope by Galileo."

[KRSESQ]

I'm curious. Doc, you travel in amature astronomy circles. I should think it possible to connect a large number of small individual telescopes via the internet, allowing them to upload their images to a single controller, which would treat the whole array as a single 'scope aimed at a single target.

You could theoretically have an optical telescope with a baseline miles wide. Has anyone tried this?

Kevin

[Dr Mordrid]

Yes. It's called an interferometer and the technique has been very useful in both optical and radio astronomy, but a very fast data connection is required. It's also been used in other widely divergent fields using numerous sensor types ranging from seismic to quantum.

[KRSESQ]

I was just wondering if it had been tried on a large scale. For instance, connecting 1000 ten-inch telescopes in this way should provide close to the resolving power of a reflector with an area of 78,500 square inches. And depending on the seperation between the 'scopes, would provide a useful parallax for calculating speeds and distances.

Or am I missing something?

Kevin

[KRSESQ]

Oops. 1000 ten-inch 'scopes would have the same light-gathering area as a single 316" telescope. Not such a great advantage for the effort, is it?

Put those same 1000 ten-inch mirrors on a single big adaptive-optics mount and you might be able to accomplish something.

Kevin

[Dr Mordrid]

Oops. 1000 ten-inch 'scopes would have the same light-gathering area as a single 316" telescope. Not such a great advantage for the effort, is it?
Kevin

Depends on how far apart they are and what your objective is.

If you place a few 10 inchers 1000 meters apart and connected them as an interferometer they would have almost the angular resolving power of a 1000 meter telescope, if not the same light gathering capability. Add more and you get more light gathering too, but at a huge increase in complexity.

Astronomers will use just 3-4 large telescopes placed on the far edges of the world for special observations where increased angular resolution is the goal.

Some large telescopes are designed with two large mirrors set up in a single binocular mount (LBT in Arizona: effective = 38 meters) or in separate domes (Keck in Hawaii: effective = 85 meters, but no optical imaging) that can be linked as interferometers to get increased angular resolution.

[KRSESQ]

I was thinking in terms of hundreds or even thousands of individual 'scopes, large and small, networked together. The actual linkup would probably be relatively straightforward. The trick, I imagine, would be gathering and synchronizing all that incoming info into a single observation.

Kevin