NSF awards $1.72 million to improve Keck laser guide star adaptive optics

Kamuela, HI--The W. M. Keck Observatory has received a $1.72 million grant from the National Science Foundation (NSF) to design the first near-infrared tip-tilt sensor used with its laser guide star adaptive optics system to correct for the turbulence in Earth’s atmosphere. The improvements will increase the sensitivity and resolution of the Keck I telescope, which already allows astronomers to resolve in the near-infrared as much detail or more as the Hubble Space Telescope resolves in visible light.

The grant from NSF’s Advanced Technologies and Instrumentation (ATI) program provides the Keck Observatory with the funding to design, construct, and implement a near-infrared tip-tilt sensor with the Keck I Laser Guide Star (LGS) Adaptive Optics (AO) system and OSIRIS, a near-infrared integral field spectrograph and imager. The new instrumentation will be developed in collaboration with Caltech Optical Observatories, which will be building the camera to be used in the sensor.

The current Keck LGS AO facilities use a wavefront sensor looking at a laser-based artificial star to measure the turbulence in the atmosphere and a deformable mirror to correct for this turbulence about 1000 times every second. The artificial star has no information about the image motion introduced by the atmosphere so currently a visible tip-tilt sensor is used to control a fast tip-tilt mirror in the AO system. The resulting images are sharp, allowing astronomers to observe minute details of cosmic objects, such as storms on Uranus or the shape of extremely distant galaxies.

The new infrared tip-tilt sensor will improve the AO performance by doing the tip-tilt sensing at near-infrared wavelengths where the stars images are smaller due to the corrections provided by the AO system, and where the stars are brighter. This will increase the amount of sky and number of cosmic objects astronomers can study with the Keck I LGS AO system. It will also provide even more resolution for astronomers to better study the birth of supermassive stars, the internal properties of early, star-forming galaxies and the existence of galaxies that have no stars and emit no light called dark matter galaxies.

In 1999, the Observatory implemented the first AO system on an 8-10 meter class telescope, the Keck II telescope, and then followed with a similar facility on Keck I in 2001. The Keck II facility was upgraded to a LGS AO facility in 2002 and a faster control system was incorporated in 2007.

Through NASA and the NSF/NOAO Telescope System Instrumentation Program, the entire U.S. community has access to the Observatory’s AO-corrected 10-meter telescopes. The Observatory provides a third of the overall U.S. community’s observing time on large telescopes, as well as to University of California, Caltech and University of Hawaii astronomers.

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the island of Hawaii and is a scientific partnership of the California Institute of Technology, the University of California, and NASA.

SOURCE: Keck Observatory; http://keckobservatory.org/news/nsf_awards_1.72_million_to_improve_keck_LGSAO/

--Posted by Gail Overton; [email protected]; www.laserfocusworld.com