Two Beams of Light
Images: (Left) The Galactic Center without adaptive optics. Image courtesy of Keck Observatory. (Right) The Galactic Center and central black hole (labeled Sgr A*) with adaptive optics. Image courtesy of Keck Observatory and the UCLA Galactic Center Group.
“Earth’s atmosphere has air currents similar to those that you see rising from a boiling pot of water or as steam rising from hot pavement at midday. These air currents are constantly rolling, disturbing the incoming light from stars. Keck Observatory has perfected a system for compensating for atmospheric turbulence, by measuring incoming starlight thousands of times per second to correct for distortions. I have watched as the Adaptive Optics system at Keck Observatory has evolved over the past 10 years, and it is truly a miracle how well this system works.” Dr. Mike Liu, Chair of the Keck Observatory Adaptive Optics (AO) Working Group and Professor of Astronomy at the University of Hawai`i
With its Laser Guide Star Adaptive Optics (LGSAO) system, Keck Observatory has firmly positioned itself as the world leader in adaptive optics astronomy. The Observatory leadership is committed to an ambitious new technology program designed to maintain Keck’s leadership role in adaptive optics for years to come. The Observatory will install a robust new laser on the Keck I Telescope before the end of 2008, and plans for a revolutionary Next Generation Adaptive Optics system, consisting of multiple laser beams, are in the design phase.
“Having Laser Guide Star Adaptive Optics on both telescopes strongly enhances the discovery potential of our observatory,” says Keck Observatory Director Taft Armandroff. “Not only does the new laser provide an additional resource on the Keck I Telescope, but it also allows for significant improvements in performance and technological innovation,” explains Armandroff.
The Keck I laser was funded in part by a grant from the National Science Foundation, and it will provide a low-power pinpoint of light that can be projected 90 kilometers up into the Earth’s atmosphere to create an artificial bright star, called a laser guide star. Keck astronomers use this laser guide star to take measurements high enough up in the atmosphere to compensate for distortions, and these measurements provide the basis for their adaptive optics corrections. The Keck I laser will improve upon the existing Keck II laser, which has been in operation since 1999, in several ways. Among its advantages, the new laser will be:
- brighter;
- more energy efficient;
- mounted on the center of the telescope as opposed to the side, which means that the laser spot (or artificial star) will be less elongated and smaller, which will improve the performance of the AO system;
- easier to maintain; and
- more reliable.
The Keck I laser will double the existing LGSAO capacity of the Observatory making this highly sought after technology more available. Additional funding is being sought from private philanthropy to pay for the installation and commissioning of the new Keck I LGSAO facility. Click the learn more to continue reading about this major technical innovation in ground-based astronomy.