A. Habib

European Extremely Large Telescope: Isopistonic angle measurements at Aklim site

As part of the Extremely Large Telescope (ELT) project, the sitetesting team at Morocco has measured from April 2008 to December 2009. The atmospheric properties at Aklim which was one of the candidates sites pre-selected. In this paper we present the isoplanatic angle 0 and the isopistonic angle p measurements at Aklim site. Statistics of the mentioned parameters are obtained from the whole data recorded using a Multi Aperture Scintillation Sensor (MASS) and a Differential Image Motion Monitor (DIMM) system. More representative results and statistics are shown hereafter.

The OTP-model applied to the Aklim site database

Within the framework of the site prospection for the future European Extremely Large Telescope (E-ELT), a wide site characterization was achieved. Aklim site located at an altitude of 2350 m at the geographical coordinates: lat.= 30°07’38” N, long.= 8°18’31” W , in the Moroccan Middle Atlas Mountains, was one of the candidate sites chosen by the Framework Programme VI (FP6) of the European Union. To complete the fulfilled study ([19]; [21]), we have used the ModelOTP (model of optical turbulence profiles) established by [15] and improved by [6]. This model allows getting the built-in profiles of the optical turbulence under various conditions. In this paper, we present an overview of the Aklim database results, in the boundary layers and in the free atmosphere separately and we make a comparison with Cerro Pachon result [15].

Astroclimate at Jbel Aklim site in Moroccan anti-atlas: 2008-2010 seeing and isoplanatic angle statistics from the E-ELT site testing data

In this paper we present an analysis of the statistical and temporal properties of seeing and isoplanatic angle measurements obtained with combined Differential Image Motion Monitor (DIMM) and Multi-Aperture Scintillation Sensor (MASS) at Jbel Aklim candidate site for the Eauropean Extremely Large Telescope (E-ELT). These data have been collected from February 2008 to Jun 2010. The overall seeing statistics for Jbel Aklim site are presented, broken into total seeing, free atmosphere seeing and isoplanatic angle, and ground-layer seeing (difference between the total and free-atmosphere seeing). We examine the statistical distributions of seeing measurements and investigate annual and nightly behavior. The properties of the seeing measurements are discussed in terms of the geography and meteorological conditions at Jbel Aklim site.

Homothetic apodization of circular aperture HACA: simulation results

In this paper we describe a new technique of circular aperture apodization. It is produced by interferometry. The light, which is diffracted by a circular aperture, is split into two beams of different amplitudes where one of them has undergone an homothety to change its radial dimensions, by using an afocal optical system. The two beams are then combined coherently to form an apodized point spread function (PSF). This procedure allows us to reduce the diffraction wings of the PSF with different reduction factors depending on the combination parameters.

Interferential seeing monitor

We present here a new approach to estimate the astronomical seeing which is a fundamental parameter in high angular resolution, in adaptive optics and site testing. Based on this approach, we developed seeing monitor, called Interferential Seeing Monitor (hereafter ISM). The principle of the ISM is based on the study of the diffraction-interference pattern produced by a Youngs double-slit in a telescope focus. From the shape of that pattern, we determine the phase difference between the diffracted light rays that meet on the image plane. Then, the phase structure function is calculated which leads to the seeing value.