BORGNINO , Julien

Anisoplanatism in Adaptive Optics or Differential Astrometry as in ground-based solar diameter measurement needs the knowledge of atmospheric turbulence profiles. MISolFA is a monitor dedicated to statistically estimate daytime turbulence profiles C-{n}**{2}(h) from solar limb agitation measurements. In order to understand the statistics of the...

Seeing monitoring in astronomy is widely based on the statistical analysis of angle-of-arrival (AA) fluctuations, which are usually modelled in the framework of the near-field approximation where diffraction through turbulence is ignored. They are consequently believed to be completely independent of wavelength. We discuss in this paper the...

The theoretical expression of the transverse angular covariance of angle-of-arrival fluctuations of the incoming wave-fronts integrated all over the telescope pupil has been established in the case of one-layer model and using the Von Kàrmàn theory. This model depends on three atmospheric parameters: the spatial coherence outer scale ${\cal...

In order to deduce significant astrophysical results from solar diameter measurements it is necessary to take an accurate account of instrumental and atmospheric effects. This paper presents a comparison between visual and charge coupled device (CCD) camera measurements performed by means of the Calern Observatory solar astrolabe during the...

High angular resolution observations of the sun are limited by atmospheric turbulence. The MISOLFA seeing monitor (still under construction) is developed to obtain spatial and temporal statistical properties of optical turbulence by analyzing local motions observed on solar edge images. The solar flying shadows used for angle-of-arrival...

The MISOLFA seeing monitor is developed to analyze spatial and temporal statistical properties of daytime optical turbulence. It is based on Angle-of-Arrival (AA) statistical properties. The MISOLFA optical de- vice measures AA-fluctuations observed as intensity variations in the pupil plane image formed through a thin slit positioned in the...

A method is presented allowing one to estimate, in the case of daytime observations, the angle-of-arrival isoplanatic patch size from the measurement of the differential image motion of the solar limb. The experimental results have been obtained using the solar astrolabe of Calern Observatory (CERGA-France). Performing a modelization as...

High angular resolution observations of the sun are limited by atmospheric turbulence. The MISOLFA seeing monitor (still under construction) is developed to obtain spatial and temporal statistical properties of optical turbulence by analyzing local motions observed on solar edge images. The solar flying shadows used for angle-of-arrival...

Optical system performances can be affected by local optical turbulence created by its surrounding environment (telescope dome, clean room, atmospheric surface layer). We present our new instrument INdoor TurbulENce SEnsor (INTENSE) dedicated to this local optical turbulence characterization. INTENSE consists of using several parallel laser...

Optical system performances can be affected by local optical turbulence created by its surrounding environment (telescope dome, clean room, or atmospheric layer). This paper follows a previous one introducing the INdoor TurbulENce SEnsor (INTENSE) instrument for optical turbulence characterization in a local area by exploitation of laser beam...

Atmospheric turbulence is responsible of the spatio-temporal fluctuations in astronomical object images obtained by means of ground-based telescopes. They are due to wave-front degradations present at the entrance of the instrument pupil plane. We first establish in this paper the formulation of the angle-of-arrival angular structure function...

Atmospheric turbulence is responsible of spatio-temporal fluctuations of astronomical object images obtained by means of ground-based telescopes. The image motion is due to the angle formed by the pupil plane with the wave-front slope all over the pupil. This defines an averaged angle of arrival which may be also considered at each point of the...

The one dimensional point spread function for long exposure frames of the whole system atmosphere-instrument is deduced from solar limb observations using data recorded at Calern Observatory (France). It is then compared to the theoretical one deduced from the Von Karman model. Good agreement is found allowing to deduce the spatial coherence...

Daily observation conditions are needed when observing the Sun at high angular resolution. MISOLFA is a daytime seeing monitor developed for this purpose that allows the estimation of the spatial and temporal parameters of atmospheric turbulence. This information is necessary, for instance, for astrometric measurements of the solar radius...

The one-dimensional point spread function for long-exposure frames of the whole system atmosphere - instrument is calculated from solar limb observations using data recorded at OCA Observatory (France). It is then compared to the theoretical one deduced from the Von Karman model and various wave-front structure functions. Good agreement is...

International audience

The future generation of extremely large telescopes will be certainly equipped with wide-field adaptive optics systems. All the components of such adaptive optics systems have to be precisely specified, and most of the technical specifications are related to atmospheric turbulence parameters, particularly the profile of the refractive index...

Diameter measurements performed with the solar astrolabe are affected by instrumental and atmospheric effects. The problem is to know how these effects contribute to the error on diameter measurements. Thus, a numerical simulation is developed to bring some responses to this problem. For this purpose, synthetic images of the Sun similar to the...

Good edge extraction from temporal series of solar images is fundamental in the solar astrolabe experiment. Noise and spots in images cause however, difficulties to extract an accurate solar edge. We present in this paper a new image-processing method which solves this problem and thus improves the characteristics of the solar astrolabe...

The statistical analysis of angle-of-arrival fluctuations appears to be well adapted to monitor the optical effects induced by the atmospheric turbulence on the images observed using ground-based telescopes. In daytime, these fluctuations may be easily observed on solar limb images. In the context of the comparison planned between solar...

Solar diameter measurements performed at Calern Observatory astrolabe during more than two solar cycles show variations at various time scales in a broad range. Due to seasonal effects and instrumental characteristics, the recorded data are not sampled uniformly and present some gaps during these years. This time series has been analyzed by...

Object images obtained by mean of ground based instrument are degraded by the earth atmosphere. Indeed, the wave-front at the entrance of the instrument pupil, present phase and amplitude random fluctuations depending of the time, the position and the line of sight. The recorded images are consequently filtered leading to bad measurements of...