Ground Layer Adaptive Optics for the W. M. Keck Observatory: Feasibility Study

TL;DR

This study assesses the feasibility of implementing a ground-layer adaptive optics system at Keck Observatory, showing potential for significant image quality improvements across optical and infrared wavelengths for various scientific applications.

Contribution

The paper evaluates the technical feasibility and scientific benefits of a GLAO system at Keck, including initial simulation results and considerations for instrument compatibility.

Findings

GLAO could improve image FWHM by 1.5x at optical wavelengths.

GLAO could improve image FWHM by 2x at infrared wavelengths.

Infrared instrument MOSFIRE is well-suited for GLAO feed.

Abstract

Ground-layer adaptive optics (GLAO) systems offer the possibility of improving the "seeing" of large ground-based telescopes and increasing the efficiency and sensitivity of observations over a wide field-of-view. We explore the utility and feasibility of deploying a GLAO system at the W. M. Keck Observatory in order to feed existing and future multi-object spectrographs and wide-field imagers. We also briefly summarize science cases spanning exoplanets to high-redshift galaxy evolution that would benefit from a Keck GLAO system. Initial simulations indicate that a Keck GLAO system would deliver a 1.5x and 2x improvement in FWHM at optical (500 nm) and infrared (1.5 micron), respectively. The infrared instrument, MOSFIRE, is ideally suited for a Keck GLAO feed in that it has excellent image quality and is on the telescope's optical axis. However, it lacks an atmospheric dispersion compensator, which would limit the minimum usable slit size for long-exposure science cases. Similarly, while LRIS and DEIMOS may be able to accept a GLAO feed based on their internal image quality, they lack either an atmospheric dispersion compensator (DEIMOS) or flexure compensation (LRIS) to utilize narrower slits matched to the GLAO image quality. However, some science cases needing shorter exposures may still benefit from Keck GLAO and we will investigate the possibility of installing an ADC.