Comparison between atmospheric turbulence models by angle-of-arrival covariance measurements

Context. In the context of astronomical observations, large-scale wavefront modelling is crucial to define specifications and to evaluate expected performances of large-aperture telescopes and long-baseline interferometers. Aim. We investigate experimentally the validity of usual models which allow to describe optical effects of atmospheric turbulence. Method. We analyse simultaneous measurements of angle-of-arrival covariances on 15 baselines of the Generalized Seeing Monitor in a linear configuration of its telescopes and modules. We use weighted least-square method on data obtained to test usual models of turbulence. Wavefront outer scale is derived from the minimization of the deviation of the model from the measurements. Results. We report first results of three nights of observations at Observatoire de Calern. We show here that the Greenwood-Tarazano model should also be considered in the characterization of optical effects of atmospheric turbulence. We have found that data are acceptably fitted by usual outer scale-dependent models in 56 per cent of recorded data.