We present the Generalised Differential Image Motion Monitor. It is a compact instrument dedicated to measure 4 parameters of the optical turbulence: seeing, isoplanatic angle, coherence time and wavefront coherence outer scale. GDIMM is based on a small telescope (28cm diameter) equipped with a 3-holes mask at its entrance pupil. The instrument is fully automatic, and performs continuous monitoring of turbulence parameters at the Calern Observatory (France). This paper gives a description of the instrument, data processing and error budget. We present also statistics of 3.5 years of monitoring of turbulence parameters above the Calern Observatory.
@article{arxiv.1904.07093,
title = {A generalized differential image motion monitor},
author = {E. Aristidi and A. Ziad and J. Chabe and Y. Fantei-Caujolle and C. Renaud and C. Giordano},
journal= {arXiv preprint arXiv:1904.07093},
year = {2019}
}