On-sky wide field adaptive optics correction using multiple laser guide stars at the MMT

TL;DR

This paper reports the first astronomical adaptive optics system at the MMT using multiple laser guide stars for ground-layer correction, significantly improving image sharpness in the near-infrared.

Contribution

It introduces a novel multi-laser guide star adaptive optics system at the MMT and demonstrates its initial successful ground-layer correction capabilities.

Findings

Reduced stellar image widths by up to 53%

Achieved correction within a 2 arcminute laser beacon constellation

Projected to reach 0.1 to 0.2 arc second resolution in near-infrared

Abstract

We describe results from the first astronomical adaptive optics system to use multiple laser guide stars, located at the 6.5-m MMT telescope in Arizona. Its initial operational mode, ground-layer adaptive optics (GLAO), provides uniform stellar wavefront correction within the 2 arc minute diameter laser beacon constellation, reducing the stellar image widths by as much as 53%, from 0.70 to 0.33 arc seconds at lambda = 2.14 microns. GLAO is achieved by applying a correction to the telescope's adaptive secondary mirror that is an average of wavefront measurements from five laser beacons supplemented with image motion from a faint stellar source. Optimization of the adaptive optics system in subsequent commissioning runs will further improve correction performance where it is predicted to deliver 0.1 to 0.2 arc second resolution in the near-infrared during a majority of seeing conditions.