Reconstruction of the ground-layer adaptive-optics point spread function for MUSE Wide Field Mode observations

TL;DR

This paper presents a fully operational PSF reconstruction method for GLAO in MUSE Wide Field Mode, validated through simulations and on-sky data, achieving high accuracy in PSF parameter estimation.

Contribution

The paper introduces a new Fourier-based PSF reconstruction algorithm tailored for GLAO in MUSE, validated with simulations and on-sky data, and made publicly available.

Findings

Achieves better than a few percent accuracy on PSF parameters

Validated with over one year of on-sky data

Algorithm is publicly available and routinely used

Abstract

Here we describe a simple, efficient, and most importantly fully operational point-spread-function(PSF)-reconstruction approach for laser-assisted ground layer adaptive optics (GLAO) in the frame of the Multi Unit Spectroscopic Explorer (MUSE) Wide Field Mode. Based on clear astrophysical requirements derived by the MUSE team and using the functionality of the current ESO Adaptive Optics Facility we aim to develop an operational PSF-reconstruction (PSFR) algorithm and test it both in simulations and using on-sky data. The PSFR approach is based on a Fourier description of the GLAO correction to which the specific instrumental effects of MUSE Wide Field Mode (pixel size, internal aberrations, etc.) have been added. It was first thoroughly validated with full end-to-end simulations. Sensitivity to the main atmospheric and AO system parameters was analysed and the code was re-optimised to account for the sensitivity found. Finally, the optimised algorithm was tested and commissioned using more than one year of on-sky MUSE data. We demonstrate with an on-sky data analysis that our algorithm meets all the requirements imposed by the MUSE scientists, namely an accuracy better than a few percent on the critical PSF parameters including full width at half maximum and global PSF shape through the kurtosis parameter of a Moffat function. The PSFR algorithm is publicly available and is used routinely to assess the MUSE image quality for each observation. It can be included in any post-processing activity which requires knowledge of the PSF.