SOWAT: High-resolution imaging with only partial AO correction.

Abstract

Observations of dense stellar systems such as globular clusters (GCs) are limited in resolution by the optical aberrations induced by atmospheric turbulence (atmospheric seeing). At the example of holographic speckle imaging, we now study, to which degree image reconstruction algorithms are able to remove residual aberrations from a partial adaptive optics (AO) correction, such as delivered from ground-layer AO (GLAO) systems. Simultaneously, we study, how such algorithms benefit from being applied to pre-corrected instead of natural point-spread functions (PSFs). We find that using partial AO corrections already lowers the demands on the holography reference star by ∼ 3 mag, what makes more fields accessible for this technique, and also that the discrete integration times may be chosen about 2 - 3× longer, since the effective wavefront evolution is slowed down by removing the perturbation power.