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Développement de la Super Station LOFAR & observations planétaires avec LOFAR

Abstract : The recent progress of ground-based radioastronomy techniques have enabled the emergence of several new projects, supported by a growing scientific community. LOFAR (the LOw Frequency ARray) is an interferometer of phased-arrays representative of this new generation of giant radiotelescopes. Its distributed architecture across Europe consist of thousands of elements grouped in "stations". It enabled to study the Universe in the ~20-250 MHz window, unexplored with a high sensitivity and high angular, temporal and spectral resolutions. The LOFAR station in Nançay has enabled the french community to participate to the LOFAR "Key Scientific Projects". It has also motivated an original instrumental development aimed at increasing significantly the capabilities of LOFAR at low frequencies (≤80 MHz). This project consists of a new giant array of sensitive antennas : the LOFAR Super Station (LSS). The first part of this thesis presents design studies of the LSS as well as the realization of a demonstrator at three characteristic scales : the elementary antenna, the "mini-array" of about twenty antennas and the global distribution of 96 such mini-arrays in Nançay. This project is designed to be both fully compatible with LOFAR and to extend its performances (especially for (exo)planetary studies), and to be a new sensitive standalone radiotelescope in Nançay. The second part of the thesis is focused on the development of a planetary imaging mode for LOFAR (as an interferometer) and its application to the study of the synchrotron emission arising from Jupiter's radiation belts. This mode enabled us to obtain the very first resolved planetary images in the band 127 - 172 MHz.
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Contributor : Julien N. Girard Connect in order to contact the contributor
Submitted on : Friday, January 2, 2015 - 6:24:35 PM
Last modification on : Wednesday, November 17, 2021 - 12:29:14 PM
Long-term archiving on: : Saturday, April 15, 2017 - 1:13:20 PM


  • HAL Id : tel-00835834, version 2


Julien N. Girard. Développement de la Super Station LOFAR & observations planétaires avec LOFAR. Instrumentation et méthodes pour l'astrophysique [astro-ph.IM]. Observatoire de Paris, 2013. Français. ⟨NNT : 2013OBSP0218⟩. ⟨tel-00835834v2⟩



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