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Session 98 - Invited Talks: Adaptive Optics.
Invited session, Wednesday, January 17
1st Floor, La Villita Assembly Building

[98.01] Adaptive optics with laser guide stars at Lick and Keck Observatories

C. E. Max (Lawrence Livermore National Laboratory)

A sodium-layer laser guide star adaptive optics system has been developed for the Shane 3 meter telescope at Lick Observatory. The adaptive optics employs a 127-actuator deformable mirror, a Hartmann wavefront sensor, and a 15 watt pulsed-dye laser tuned to the resonance line of atomic sodium at 589 nm.

Engineering tests of the adaptive optics system using natural reference stars yield up to a factor of 12 increase in peak intensity of point-like objects and a factor of 6.5 reduction in full width at half maximum, consistent with theoretical predictions. The adaptive optics system is being used for near infrared astronomical observations of objects with visual magnitudes of 10 or brighter. We have begun to investigate young stellar objects and planetary nebulae, and to search for companions of nearby stars.

The sodium laser guide star is in the process of being commissioned for astronomical use. The laser, which is mounted on the telescope, creates a spot of about 1 meter diameter in the sodium layer, and has an equivalent visual magnitude of about m = 9 corresponding to a return signal of about 0.2 photons per square cm per msec. We have demonstrated the first sodium laser guide star correction of higher-order wavefront error with this system.

Adaptive optics and laser guide star systems are currently being designed for the Keck Telescope, for use with a new high-resolution near infrared camera and spectrograph. An overview of these systems will be given, together with their expected performance.

Program listing for Wednesday