Turbulence monitoring at Calern observatory with the Generalised Differential Image Motion Monitor

TL;DR

This paper presents long-term turbulence monitoring at Calern observatory using the GDIMM instrument, which measures key atmospheric parameters affecting astronomical observations, and derives additional turbulence characteristics from the data.

Contribution

It introduces the application of GDIMM for continuous turbulence monitoring at Calern and provides long-term statistical analysis of atmospheric turbulence parameters.

Findings

Long-term turbulence data collected at Calern observatory.

Derived turbulence altitude and wind speed from GDIMM measurements.

Seasonal variations in turbulence parameters observed.

Abstract

The Generalised Differential Image Motion Monitor (GDIMM) was proposed a few years ago as a new generation instrument for turbulence monitoring. It measures integrated parameters of the optical turbulence, i.e the seeing, isoplanatic angle, scintillation index, coherence time and wavefront coherence outer scale. GDIMM is based on a fully automatic small telescope (28cm diameter), equipped with a 3-holes mask at its entrance pupil. The instrument is installed at the Calern observatory (France) and performs continuous night-time monitoring of turbulence parameters. In this communication we present long-term and seasonnal statistics obtained at Calern, and combine GDIMM data to provide quantities such as the equivalent turbulence altitude and the effective wind speed.