M. Sabil

European Extremely Large Telescope Site Characterization I: Overview

ABSTRACT.The site for the future European Extremely Large Telescope (E-ELT) is already known to be Armazones, near Paranal (Chile). The selection was based on a variety of considerations, with an important one being the quality of the atmosphere for the astronomy planned for the ELT. We present an overview of the characterization of the atmospheric parameters of candidate sites, making use of standard procedures and instruments as carried out within the Framework Programme VI (FP6) of the European Union. We have achieved full characterization of the selected sites for the parameters considered. Further details on adaptive optics results and climatology will be the subject of two forthcoming articles. A summary of the results of the FP6 site-testing campaigns at the different sites is provided.

European Extremely Large Telescope Site Characterization. II. High Angular Resolution Parameters

ABSTRACT.This is the second article of a series devoted to European Extremely Large Telescope (E-ELT) site characterization. In this article we present the main properties of the parameters involved in high angular resolution observations from the data collected in the site testing campaign of the E-ELT during the design study (DS) phase. Observations were made in 2008 and 2009, in the four sites selected to shelter the future E-ELT (characterized under the ELT-DS contract): Aklim mountain in Morocco, Observatorio del Roque de los Muchachos (ORM) in Spain, Macon range in Argentina, and Cerro Ventarrones in Chile. The same techniques, instruments, and acquisition procedures were taken on each site. A multiple aperture scintillation sensor (MASS) and a differential image motion monitor (DIMM) were installed at each site. Global statistics of the integrated seeing, the free atmosphere seeing, the boundary layer seeing, and the isoplanatic angle were studied for each site, and the results are presented here. ...

First characterization of Jbel Aklim in Moroccan Anti-Atlas as a potential site for the E-ELT Meteorological parameters and seeing measurements

Context. In the framework of the European Extremely Large Telescope project (E-ELT), a survey of prospective sites was launched by the European Southern Observatory (ESO) to select a site to host the next generation of optical telescopes of 42 m diameter, i.e., the E-ELT. The Moroccan Anti-Atlas (Jbel Aklim) was selected as one of these sites. Aims. We present an analysis of meteorological parameters and seeing measurements at Aklim, the Moroccan prospective site of the E-ELT project. Methods. We initiated a preliminary campaign to measure the astronomical seeing at Jbel Aklim using a differential image motion monitor (DIMM) instrument. We installed a weather station 2 m above the ground level to measure meteorological parameters such as temperature, relative humidity, pressure, wind speed, and wind direction. Results. We present data obtained by the DIMM monitor during 105 nights. The median and mean values of the seeing for the entire period of observation are 0.72 �� and 0.79 �� , respectively, with a standard deviation of 0.31 �� . The best value of the seeing obtained during this period is 0.30 �� . A seasonal analysis of meteorological parameters are presented. We also used data from the National Center for Environmental Prediction/National Center for Atmospheric Research reanalysis database (NCEP/NCAR) to derive more information about the long-term evolution of atmospheric parameters at Aklim site. Conclusions. Our preliminary results indicate that Aklim has indeed good conditions for conducting astronomical observations and could be a site to host a future astronomical observatory, even of E-ELT dimensions.

European Extremely Large Telescope Site Characterization III: Ground Meteorology

Both meteorology and optical conditions are crucial for selecting the best site to host extremely large telescopes such as the Thirty Meter Telescope (TMT) and the European project (E-ELT). For the E-ELT, a year-long meteorological campaign was performed at our two reference sites, the Observatorio del Roque de los Muchachos (ORM) and Cerro Ventarrones (very close to the VLT site at Paranal), and at other sites also considered as alternatives to the reference sites: Aklim, Macon, and Izana (Observatorio del Teide; OT). In this article, we present a statistical analysis of the ground meteorological properties recorded at these sites, making use of automatic weather stations (AWSs) equipped with standard meteorological sensors providing the air temperature, relative humidity, barometric pressure, wind speed, and wind direction, using standard procedures across all sites. Meteorology offers but one discriminant in the complicated question of where to site such a major facility as the E-ELT (other factors being seeing, local geology, the economics of the logistics, etc.), both for determining the feasibility of telescope and instrumentation design and construction and for determining the useful observing time. However, the final decision of where to locate a major telescope depends in part on all these—and other—considerations and not on any one criterion alone. In summary, for 90% of the nighttime, the wind speed is lower than 18 m s-1, the telescope operational limit at all the sites except Macon. For this reason, Macon was discarded in the final site selection as, for 25% of the time, the wind speed is greater than 17 m s-1. The smallest nighttime temperature gradient is at ORM, whereas the lowest mean relative humidity value is reached at the Ventarrones site. Izana was discarded in the site selection study from the very beginning due to lack of funding to install further site-testing equipement (e.g., Multi-Aperture Scintillation Sensor-Differential Image Motion Monitor (MASS-DIMM)). We investigate the statistical distributions of annual and monthly meteorological conditions for day and night separately. This is the third paper in a series discussing the E-ELT FP6 site characterization project.

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.

First characterization of Jbel Aklim in Moroccan Anti-Atlas as a potential site for the E-ELT

In the framework of the E-ELT project a prospecting campaign was launched by the ESO to select the site that will host the next generation of optical telescopes of 42 m diameter. Moroccan Anti-Atlas (Jbel Aklim) was selected as well as other sites (ORM, Ventarrones and Macon) to be a possible potential location that will house the E-ELT. In this paper we first present the reasons for the choice of Jbel Aklim as a E-ELT candidate through various exploration campaigns that we have achieved. The second part concerns description of instruments used. Finally we will present the preliminary results of the meteorological and MASS-DIMM measurements.

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.

Meteorological parameters analysis above Oukaimeden Observatory using NCEP/NCAR data

We present a characterization of meteorological parameters: Wind and direction speed, temperature, relative humidity and pressure. Data set is provided by the system of NCEP/NCAR Re-analysis. The statistical treatment of data will cover the years between 2003 and 2006 for the Observatory Oukaïmeden. An analysis of monthly, seasonal, and annual results is presented. We calculated the Richardson number for each month of the year. In addition, this paper describes a comparison between balloon-sounding made at different stations and coincident model-based meteorological analysis. The comparison allows the assessment reliability of the analysis in studied period.

Oukaimeden Observatory: detection of exoplanet HD 189733b by the transit method

In this paper we report the detection and characterization of HD 189733b, the peculiarity of this exoplanet is that the flow of the target star is decreased significantly (~ 3%) during the transit. We determined the radius of the exoplanet 1.27 ± 0.03 RJ, the impact parameter 0.70 ± 0.02, and the inclination of the orbit 85.4 ± 0.1°. The transit of the extrasolar planet HD 189733b is already done using the larger telescope. In this study, we used during the observation a telescope of modest size.