Atmospheric turbulence profiling with the Multistar Turbulence Monitor

TL;DR

The paper evaluates the Multistar Turbulence Monitor's ability to accurately profile atmospheric turbulence and compare its performance with existing methods through simulations and on-sky observations.

Contribution

It provides a comprehensive analysis of the MTM method, demonstrating its robustness, accuracy, and practical utility for atmospheric turbulence profiling.

Findings

MTM accurately recovers turbulence profiles and seeing conditions.

MCMC inversion yields stable results with uncertainty estimates.

MTM results closely match DIMM measurements across multiple nights.

Abstract

Accurate characterization of atmospheric optical turbulence is essential for evaluating astronomical sites and optimizing adaptive optics systems. The Multistar Turbulence Monitor (MTM) infers the vertical distribution of the refractive-index structure constant Cn2(z) from differential image motion measured between multiple stellar pairs in short-exposure frames. We present a comprehensive investigation of the MTM method, combining theoretical analysis, instrument-performance assessment, numerical simulations, and on-sky observations obtained at the Daocheng Astronomical Site. Simulations based on a standard HV turbulence model demonstrate that the inversion pipeline robustly recovers both the integrated seeing and the vertical turbulence profile under realistic centroiding noise and varying pixel scales. The Markov Chain Monte Carlo (MCMC) inversion achieves stable results with thirteen discrete height nodes and provides reliable uncertainties. Three nights of MTM measurements at the Daocheng Astronomical Site show that MTM-derived seeing closely tracks simultaneous Differential Image Motion Monitor (DIMM) results, accurately reproducing both short-term fluctuations and nightly averages. These results confirm that MTM provides a simple, portable, and versatile solution for atmospheric turbulence profiling and routine seeing monitoring.