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International Heliophysical Year: GPS Network in Africa / C. Amory-Mazaudier in Earth, Moon, and Planets, vol 104 n° 1-4 (April 2009)  

Public [article]  inEarth, Moon, and Planets > vol 104 n° 1-4 (April 2009) . - pp 263 - 270 Titre : International Heliophysical Year: GPS Network in Africa Type de document : Article/Communication Auteurs : C. Amory-Mazaudier, Auteur ; S. Basu, Auteur ; Olivier Bock , Auteur ; A. Combrink, Auteur ; et al., Auteur Année de publication : 2009 Article en page(s) : pp 263 - 270 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] Afrique (géographie politique) [Termes IGN] récepteur GPS [Termes IGN] système Terre-Lune Résumé : (auteur) The main scientific objectives of the International Heliophysical Year are to discover and study all the physical processes coupling the Earth to the Sun. During the IHY a number of scientific instruments are being deployed all over the world. This brief report presents the scientific objectives, the GPS receiver network over Africa and the long lasting research planned for the next decades in Africa. Numéro de notice : A2009-578 Affiliation des auteurs : IGN+Ext (1940-2011) Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s11038-008-9273-8 En ligne : https://doi.org/10.1007/s11038-008-9273-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=88644 [article]

Relativistic motion of gyroscopes and space gradiometry / E. Gill (1992)

Public Titre : Relativistic motion of gyroscopes and space gradiometry Type de document : Monographie Auteurs : E. Gill, Auteur ; Michael Soffel, Auteur ; H. Ruder, Auteur ; Monique Schneider, Auteur Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 1992 Collection : DGK - A Sous-collection : Theoretische Geodäsie num. 107 Importance : 82 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-7696-8189-5 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] champ de gravitation [Termes IGN] corps céleste [Termes IGN] équation de Hamilton-Jacobi [Termes IGN] force d'inertie [Termes IGN] gradiométrie [Termes IGN] gyroscope [Termes IGN] linéarisation [Termes IGN] mécanique céleste [Termes IGN] métrique [Termes IGN] précession [Termes IGN] système Terre-Lune Index. décimale : 30.60 Géodésie spatiale Résumé : (Auteur) Relativistic effects in the motion of freely falling test particles moving along circular orbits in the exterior gravitational field of a spherically symmetric, slowly rotating or slightly oblate body are considered. To this end we solve the geodesic equation in the (parametrized) post-Newtonian metric, the linearized Kerr metric and the linearized Erez-Rosen metric, respectively. The main part of this article deals with the "pseudo-Newtonian resonances" found by MASHHOON and THEISS (1982-1986) in the motion of torque-free gyroscope axes, moving along inclined orbits in the gravitational field of a rotating mass. In relativistic spin motion and gradiometry these "resonances" should lead to new effects on time scales, comparable or large to the Fokker period. In this regime, it was argued, the usual post-Newtonian approximation should break down. However, solving the equations of parallel transport in the first post-Newtonian approximation, we show that the Mashhoon-Theiss "anomaly" appears already at this level and can be explained as arising from a simple interplay between Fokker (geodetic) and Schiff (Lense-Thirring) precession. For these reasons the Mashhoon-Theiss "anomaly" represents no new anomalous relativistic effect, but can be understood by means of the usual post-Newtonian formalism. Considering the motion of some torque-free gyroscope along circular orbits with small inclination in the gravitational field of an oblate body, where according to THEISS (1985b) similar relativistic resonances should appear, we show that no new interesting relativistic effects occur in that case. To investigate relativistic effects in space gradiometry we calculate the relativistic tidal forces in a local inertial system, using the previously derived results for geodesic and spin motion. According to the development of high precision superconducting satellite gradiometers the measurement of gravito-magnetic effects of the Earth's rotation may in principle be achieved in the near future. Analyzing the motion of the Earth-Moon system in the gravitational field of the rotating Sun, we find that gravito-magnetic effects can be neglected. Especially, taking into account the Newtonian precession of the Moon's orbit the Mashhoon-Theiss "anomaly" leads to a variation of the Earth-Moon distance with amplitude 0.4 /µm, in contrast to the results of Mashhoon and Theiss of 1.4 m (MASHHOON et al. 1986). Relativistic effects of the quadrupole moment of the central field can be neglected in satellite gradiometry and the motion of the Earth-Moon system, respectively. Numéro de notice : 40655 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Monographie Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=57824

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Precise modelling aspects of lunar laser measurements and their use for the improvement of geodetic parameters / A. Stolz (1979)

Public Titre : Precise modelling aspects of lunar laser measurements and their use for the improvement of geodetic parameters Type de document : Monographie Auteurs : A. Stolz, Auteur Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 1979 Collection : DGK - A Sous-collection : Theoretische Geodäsie num. 090 Importance : 23 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-7696-8173-4 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] marée terrestre [Termes IGN] mouvement du pôle [Termes IGN] photon [Termes IGN] propagation du signal [Termes IGN] système Terre-Lune [Termes IGN] télémétrie laser sur la Lune [Termes IGN] temps universel Index. décimale : 30.40 Géodésie physique Résumé : (Auteur) A step-by-step description of the modelling of the lunar laser two-way time-delay is presented. The formulas employed for diurnal polar motion, short-period tidal variations in universal time (UT), the effects of the earth's non-rigidity on the nutation series, horizontal and vertical components of earth-tidal deformation, retardation of the photon by the atmosphere, and relativistic effects on the mea-surement of time and on the path of the photon are given. The use of the data for improving telescope coordinates, polar motion and UT is described. Also dis-cussed are the correlations which exist between ephemeris errors and errors in UT and polar motion, and between errors in UT and the y coordinate of the pole. Numéro de notice : 28231 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Monographie Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=63577

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