CHARA Array adaptive optics: complex operational software and performance

TL;DR

This paper details the development and initial testing of adaptive optics software for the CHARA Array, significantly enhancing its sensitivity and operational efficiency for observing faint astronomical targets.

Contribution

It introduces the complex adaptive optics software integrated into the CHARA Array and demonstrates its effectiveness through initial on-sky tests.

Findings

Increased scientific throughput due to sensitivity gains.

Extended observing time under worse seeing conditions.

Successful operation of 12 AO systems across 6 telescopes.

Abstract

The CHARA Array is the longest baseline optical interferometer in the world. Operated with natural seeing, it has delivered landmark sub-milliarcsecond results in the areas of stellar imaging, binaries, and stellar diameters. However, to achieve ambitious observations of faint targets such as young stellar objects and active galactic nuclei, higher sensitivity is required. For that purpose, adaptive optics are developed to correct atmospheric turbulence and non-common path aberrations between each telescope and the beam combiner lab. This paper describes the AO software and its integration into the CHARA system. We also report initial on-sky tests that demonstrate an increase of scientific throughput by sensitivity gain and by extending useful observing time in worse seeing conditions. Our 6 telescopes and 12 AO systems with tens of critical alignments and control loops pose challenges in operation. We describe our methods enabling a single scientist to operate the entire system.