High-resolution imaging and spectroscopy in the visible from large ground-based telescopes with natural guide stars

TL;DR

This paper proposes a novel combination of low order adaptive optics and Lucky Imaging with photon counting CCDs to achieve near-diffraction limited visible imaging on large ground-based telescopes using natural guide stars.

Contribution

It introduces a new approach combining adaptive optics and Lucky Imaging techniques to enable high-resolution visible observations across the sky with faint guide stars.

Findings

Achieves 20-25 milliarcsecond resolution in the visible.

Demonstrates effectiveness with guide stars as faint as magnitude 18.5.

Proposes an instrument design for efficient integral field spectroscopy.

Abstract

Near-diffraction limited imaging and spectroscopy in the visible on large (8-10 meter) class telescopes has proved to be beyond the capabilities of current adaptive optics technologies, even when using laser guide stars. The need for high resolution visible imaging in any part of the sky suggests that a rather different approach is needed. This paper describes the results of simulations, experiments and astronomical observations that show that a combination of low order adaptive optic correction using a 4-field curvature sensor and fast Lucky Imaging strategies with a photon counting CCD camera systems should deliver 20-25 milliarcsecond resolution in the visible with reference stars as faint as 18.5 magnitude in I band on large telescopes. Such an instrument may be used to feed an integral field spectrograph efficiently using configurations that will also be described.