A new image released today reveals how Gemini Observatory's most advanced adaptive optics (AO) system will help astronomers study the universe with an unprecedented level of clarity and detail by removing distortions due to the Earth's atmosphere. The photo, featuring an area on the outskirts of the famous Orion Nebula, illustrates the instrument's significant advancements over previous-generation AO systems.
"The combination of a constellation of five laser guide stars with multiple deformable mirrors allows us to expand significantly on what has previously been possible using adaptive optics in astronomy," said Benoit Neichel, who currently leads this adaptive optics program for Gemini. "For years our team has focused on developing this system, and to see this magnificent image, just hinting at its scientific potential, made our nights on the mountain - while most folks were celebrating the New Year's holiday - the best celebration ever!"
The new system, called GeMS, is installed on the Gemini South telescope in Chile and is the first of its kind to use laser guide stars and a technology called Multi-Conjugate Adaptive Optics (MCAO) to image the sky. Motivated by MCAO's potential to produce a significantly larger field-of-view and more uniform corrections than previous AO systems, former Gemini scientist François Rigaut (now at the Australian National University), first suggested the system's development at Gemini over 10 years ago. According to Rigaut, "It's a great feeling to see this system on the sky and doing cutting-edge science. When it's all theoretical you dream of what it will someday do to improve our vision of the cosmos. An image like this makes it so real - it's worth all the mental sweat!"
"Adaptive optics allows ground-based telescopes to take full advantage of their large mirrors," notes Dr. Gary Schmidt, Gemini program director for the U.S. National Science Foundation. "Gemini's development of MCAO leads the world, and its fidelity even surpasses that of current - and far more expensive - orbiting observatories for imaging the sky."
This milestone also bodes well for future generations of large ground-based telescopes. "As telescopes get larger they look through more and more of the Earth's atmosphere and this is a problem," said Gary Sanders, Project Manager of the 30-Meter Telescope (TMT) Project. Sanders emphasizes that it is imperative that we find new and innovative ways to solve this problem by removing the distortions caused by the turbulent air overhead. "MCAO is a key technology that makes the next generation of large telescopes, like the TMT, justifiable. It allows us to use the light we collect more efficiently and see the universe more sharply than ever before in human history," said Sanders.
About five years ago, when GeMS was under development, and still just a vision for Rigaut and the team, Gemini Observatory released an image of a smaller section of this area of the Orion Nebula known as the "Orion Bullets." That image demonstrated the power of Gemini's AO system called Altair - which is still actively used at the Gemini North telescope. Gemini's instrument scientist for Altair, Chad Trujillo, points out that in one shot GeMS covers a significantly larger field-of-view than Altair and, he adds, "The uniformity and performance across the image is amazing! In this new image, the pixels are 2.5 times finer and there are about 16 times more of them. Both the correction quality and the field-of-view are considerably better than the previous generation of AO systems."
THE MCAO ADVANTAGE
The technology behind MCAO involves the use of multiple laser guide stars (five in the GeMS system) and several deformable mirrors (three in all) to sample atmospheric distortions and cancel them out in real-time as imaging data is collected. Using algorithms similar to those developed for medical tomographic imaging the GeMS MCAO system creates a three-dimensional snapshot of atmospheric turbulence about 500 to 1000 times per second. The result is about a 16-fold increase in the patch of sky observed, while