Stellar photometry with Multi Conjugate Adaptive Optics

TL;DR

This paper reviews the current state of stellar photometry using Multi Conjugate Adaptive Optics at large telescopes, emphasizing the precision achieved in crowded stellar environments and the need for improved algorithms.

Contribution

It provides an overview of photometric analysis techniques with MCAO, presents new results on globular cluster photometry, and discusses future algorithmic improvements.

Findings

Achieved photometric precision in crowded fields reaching Ks ~21.5 mag

Demonstrated the effectiveness of DAOPHOT in MCAO images

Highlighted the importance of stellar standards for performance assessment

Abstract

We overview the current status of photometric analyses of images collected with Multi Conjugate Adaptive Optics (MCAO) at 8-10m class telescopes that operated, or are operating, on sky. Particular attention will be payed to resolved stellar population studies. Stars in crowded stellar systems, such as globular clusters or in nearby galaxies, are ideal test particles to test AO performance. We will focus the discussion on photometric precision and accuracy reached nowadays. We briefly describe our project on stellar photometry and astrometry of Galactic globular clusters using images taken with GeMS at the Gemini South telescope. We also present the photometry performed with DAOPHOT suite of programs into the crowded regions of these globulars reaching very faint limiting magnitudes Ks ~21.5 mag on moderately large fields of view (~1.5 arcmin squared). We highlight the need for new algorithms to improve the modeling of the complex variation of the Point Spread Function across the field of view. Finally, we outline the role that large samples of stellar standards plays in providing a detailed description of the MCAO performance and in precise and accurate colour{magnitude diagrams.