PSF Variation and Crowded Field Photometry with Laser Guide Star
Adaptive Optics

Nate McCrady
UCLA

ABSTRACT

Adaptive optics systems on large telescopes have led to stunning
astronomical images and broken open fields of study ranging from planetary
atmospheres and brown dwarfs to massive clusters of young stars.  The
unprecedented resolution of AO images in the infrared has greatly enhanced
studies of the center of our Galaxy, long shrouded from view by
intervening dust.  Observations of the crowded star fields of the Galactic
Center and dense, young star clusters take full advantage of the high
angular resolution of laser guide star AO images.  But AO imaging comes at
a cost: temporal variation and incomplete information about atmospheric
turbulence result in spatial variation of the shape of the response to a
point source across the field of view.  I will discuss current efforts to
characterize this variation of the AO point spread function and the
resulting limits on precision astrometry, photometry and source
identification in crowded star fields.