Multi-star Turbulence Monitor: A new technique to measure optical turbulence profiles

TL;DR

This paper introduces a novel technique using short-exposure star images to measure atmospheric turbulence profiles, enabling better characterization of optical turbulence for telescopes, validated through simulations and real data.

Contribution

A new method leveraging differential star image motion to accurately estimate turbulence profiles and atmospheric parameters with small telescopes.

Findings

Successfully estimates turbulence profiles and seeing conditions.

Validated with Monte-Carlo simulations and real telescope data.

Provides a practical approach for atmospheric turbulence measurement.

Abstract

The strength and vertical distribution of atmospheric turbulence is a key factor determining the performance of optical and infrared telescopes, with and without adaptive optics. Yet, this remains challenging to measure. We describe a new technique using a sequence of short-exposure images of a star field, obtained with a small telescope. Differential motion between all pairs of star images is used to compute the structure functions of longitudinal and transverse wavefront tilt for a range of angular separations. These are compared with theoretical predictions of simple turbulence models by means of a Markov-Chain Monte-Carlo optimization. The method is able to estimate the turbulence profile in the lower atmosphere, the total and free-atmosphere seeing, and the outer scale. We present results of Monte-Carlo simulations used to verify the technique, and show some examples using data from the second AST3 telescope at Dome A in Antarctica.