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1. First approximation for spacecraft motion relative to (99942) Apophis.

Author: S. Aljbaae, Diogo Merguizo Sanchez, Antônio Fernando Bertachini de Almeida Prado, J. Souchay, M. O. Terra, Rodolfo Batista Negri, and L. O. Marchi
Published: 2020

2. Gaia Early Data Release 3 The Gaia Catalogue of Nearby Stars

Author: Zoltan Balog, G. Tauran, Vincenzo Ripepi, Gerry Gilmore, M. Barros, Łukasz Wyrzykowski, Alberto Cellino, E. Poggio, P. Gavras, Simchon Faigler, Marc Audard, C. Nicolas, M. Vaillant, A. Mora, Paolo Tanga, Silvio Leccia, Despina Hatzidimitriou, A. Dapergolas, Eva Sciacca, Alberto Krone-Martins, N. Cheek, M. Hauser, Ulrike Heiter, S. Managau, L. Rohrbasser, Mathias Schultheis, E. Utrilla, Minia Manteiga, Marcella Marconi, Xavier Luri, F. De Angeli, Shay Zucker, Paolo Giacobbe, J. Juaristi Campillo, H. I. Siddiqui, J. Torra, F. X. Pineau, Roy Gomel, Thierry Morel, T. Cornez, Eric Gosset, Mario Gai, Jose M Hernandez, G. Giuffrida, A. de Torres, Laszlo Szabados, S. Ragaini, E. van Dillen, D. Semeux, Leanne P. Guy, R. Drimmel, L. M. Sarro, S. Voutsinas, Johannes Sahlmann, Damien Ségransan, S. Liao, Derek W. Morris, Jan Rybizki, André Moitinho, T. Roegiers, Bengt Edvardsson, Tristan Cantat-Gaudin, Martin Altmann, C. Turon, Laurent Chemin, K. Janßen, D. Garabato, Alejandra Recio-Blanco, Michał Pawlak, Lorenzo Rimoldini, Sergei A. Klioner, F. Torra, Carine Babusiaux, Alfred Castro-Ginard, G. Plum, Mariateresa Crosta, Iain A. Steele, A. Yoldas, Alex Lobel, J.-L. Bassilana, Harry Enke, Rosanna Sordo, Francesca Fragkoudi, F. De Luise, M. Bernet, Alessandro Sozzetti, M. Kontizas, Roberto Molinaro, C. Diener, S. Regibo, D. Barbato, T. Pauwels, R. E. de Souza, C. Fabricius, D. Souami, L. Martin Polo, M. Ramos-Lerate, Douglas J. Marshall, A. G. Butkevich, P. Madrero Pardo, P. Re Fiorentin, J. F. Le Campion, Jérôme Berthier, N. Tonello, Ummi Abbas, Y. Lebreton, M. Biermann, D. Munoz, N. Brouillet, David Teyssier, O. Vanel, P. A. Palicio, A. Jean-Antoine Piccolo, A. F. Lanza, Jesus Salgado, E. del Pozo, Antti Penttilä, R. Geyer, Ramachrisna Teixeira, L. Chaoul, Mike Smith, Rossella Cancelliere, J. M. Martín-Fleitas, D. Baines, M. Romero-Gómez, E. Anglada Varela, E. Livanou, X. Peñalosa Esteller, S. Diakite, Alberto Vecchiato, Thomas Wevers, Daniel Hestroffer, Sebastian L. Hidalgo, M. David, Angela Bragaglia, J. De Ridder, Mark Taylor, Roberto Morbidelli, A. Sagristà Sellés, Nigel Hambly, Arnaud Siebert, R. L. Smart, P. Burgess, Y. Le Fustec, Alessandro Bressan, H. Steidelmüller, Alberto Riva, H. E. Huckle, Morgan Fouesneau, N. Bauchet, P. Osborne, S. Marinoni, Krzysztof A. Rybicki, A. Masip, Laia Casamiquela, R. Messineo, A. Garofalo, Antonella Vallenari, R. Mor, Sahar Shahaf, P. de Laverny, G. Sadowski, Peter G. Jonker, A. Kochoska, F. Taris, A. F. Mulone, M. Ajaj, C. Ducourant, T. A. Lister, F. A. Jansen, Ruth Carballo, J. M. Carrasco, Tatiana Muraveva, W. van Reeven, P. Sartoretti, Jordi Portell, Andreas Korn, E. Salguero, Ana Ulla, P. Di Matteo, Coryn A. L. Bailer-Jones, J. Bakker, F. Riclet, G. Altavilla, Ulrich Bastian, P. Esquej, R. Buzzi, M. Segol, A. C. Lanzafame, L. Balaguer-Núñez, Beatrice Bucciarelli, C. Panem, E. Balbinot, T. Carlucci, Davide Massari, P. de Teodoro, Sébastien Lambert, M. I. Carnerero, Amina Helmi, F. Solitro, C. Robin, Carlos Dafonte, Tsevi Mazeh, A. Panahi, C. Fabre, Sergi Blanco-Cuaresma, Deborah Busonero, Maroussia Roelens, O. Marchal, Tomaz Zwitter, B. Holl, G. Holland, William Thuillot, Michael Davidson, E. Licata, Michele Bellazzini, Teresa Antoja, E. Szegedi-Elek, Francesca Figueras, Eric Slezak, Sergio Messina, N. Samaras, E. Poujoulet, Mark Cropper, A. Burlacu, R. Blomme, Elmé Breedt, Annie C. Robin, H. E. Delgado, Z. Kostrzewa-Rutkowska, Georges Kordopatis, Conny Aerts, L. Noval, Daniel Michalik, P. J. Richards, L. Karbevska, Grigori Fedorets, Maria Süveges, F. Crifo, J. Guiraud, D. Eappachen, K. Kruszyńska, Gisella Clementini, P. Yvard, Carme Jordi, L. Bramante, G. Busso, P. David, E. Fraile, Ugo Becciani, A. Lorca, Sanjeev Khanna, Alex Bombrun, Isabella Pagano, C. Dolding, A. M. Piersimoni, Paolo Montegriffo, A. Abreu Aramburu, Anthony G. A. Brown, Simon Hodgkin, Ennio Poretti, M. Fabrizio, I. Gonzalez-Santamaria, N. A. Walton, P. Panuzzo, Benoit Carry, Raphael Guerra, J. J. González-Vidal, T. Lebzelter, Nami Mowlavi, C. Barache, M. M. S. Marcos Santos, S. Cowell, Marco Castellani, J. J. Aguado, N. R. Millar, A. Baudesson-Stella, N. Leclerc, S. Bartolomé, J. Álvarez Cid-Fuentes, F. van Leeuwen, S. Bouquillon, Uwe Lammers, D. W. Evans, L. Eyer, M. van Leeuwen, A. Guerrier, J. González-Núñez, H. E. P. Lindstrøm, Miguel García-Torres, Ilaria Musella, L. Palaversa, W. Roux, W. Löffler, J.-B. Delisle, Dimitri Pourbaix, Timo Prusti, J. Osinde, M. Riello, G. Orrù, C. Crowley, Alessandra Mastrobuono-Battisti, Hector Canovas, D. L. Harrison, Y. Lasne, E. F. del Peloso, Laurent Galluccio, N. Hładczuk, T. Boch, Martin A. Barstow, László Molnár, Aldo Dell'Oro, C. Pagani, Krzysztof Nienartowicz, Stefano Bertone, Patrick Charlot, Eduard Masana, Elisabetta Caffau, N. Robichon, Luciana Bianchi, Federica Spoto, Felix Franke, J. L. Halbwachs, R. Gutiérrez-Sánchez, L. Pulone, Yassine Damerdji, Frédéric Arenou, Richard I. Anderson, Elena Pancino, David Hobbs, P. Castro Sampol, Yves Fremat, Pierre Kervella, C. Zurbach, Sofia Randich, Robert G. Mann, J. C. Segovia, Diego Bossini, D. Katz, Nicholas Rowell, P. Ramos, E. Racero, G. Gracia-Abril, R. Santoveña, R. Haigron, N. Unger, Enrique Solano, S. G. Baker, W. J. Cooper, F. Royer, S. Accart, George M. Seabroke, João Alves, Emese Plachy, Thomas Hilger, Pedro García-Lario, Gérard Jasniewicz, Kevin Benson, Christos Siopis, J. Souchay, Agnes Fienga, Giovanni Comoretto, F. Julbe, A. Hutton, Pierre Fernique, Céline Reylé, F. Pailler, Stefan Jordan, J. H. J. de Bruijne, C. A. Stephenson, E. Gerlach, Elisa Distefano, Karri Muinonen, Y. Viala, H. Zhao, L. Siltala, C. P. Murphy, Maria-Rosa L. Cioni, Andrea Chiavassa, D. Molina, J. Fernández-Hernández, G. Jevardat de Fombelle, Federico Marocco, Nicoletta Sanna, Alexey Mints, Juan Zorec, Ángel Gómez, I. Bellas-Velidis, M. G. Lattanzi, C. M. Raiteri, E. Brugaletta, Mikael Granvik, O. L. Creevey, Guy Rixon, Francois Mignard, P. M. Marrese, M. A. Álvarez, Caroline Soubiran, Rene Andrae, C. Ordénovic, A. Delgado, V. Sanchez Gimenez, J. Castañeda, D. Vicente, R. De March, A. Garcia-Gutierrez, M. Weiler, F. Thévenin, Lennart Lindegren, Isabelle Lecoeur-Taïbi, Jon Marchant, Monica Rainer, Alessandro Spagna, Andrej Prsa, M. Sarasso, Nicolas Rambaux, Paul J. McMillan, Ludovic Delchambre, M. Garcia-Reinaldos, M. Haywood, C. Fouron, S. Girona, Ministerio de Economía y Competitividad (España), Ministerio de Ciencia, Innovación y Universidades (España), Universidad de Barcelona, Xunta de Galicia, Generalitat de Catalunya, INAF - Osservatorio Astrofisico di Torino (OATo), Istituto Nazionale di Astrofisica (INAF), Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213) (UTINAM), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Centre National d'Études Spatiales [Toulouse] (CNES), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Astronomische Rechen-Institut [Heidelberg] (ARI), Zentrum für Astronomie der Universität Heidelberg (ZAH), Universität Heidelberg [Heidelberg]-Universität Heidelberg [Heidelberg], Systèmes de Référence Temps Espace (SYRTE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Observatoire astronomique de Strasbourg (ObAS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Mésocentre de calcul (MESOCENTRE), Université de Franche-Comté (UFC), Centre de Données Astronomiques de Strasbourg, Partenaires INRAE, Géoazur (GEOAZUR 7329), Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA), Laboratoire Univers et Particules de Montpellier (LUPM), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Montpellier 2 - Sciences et Techniques (UM2), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), THALES, Université de Namur [Namur] (UNamur), Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France, Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Universität Heidelberg [Heidelberg] = Heidelberg University-Universität Heidelberg [Heidelberg] = Heidelberg University, Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), THALES [France], Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Universidad de Cantabria, Gaia Collaboration, Planetary-system research, Department of Physics, Particle Physics and Astrophysics, Astronomy, and ITA
Subjects: trigonometric parallaxes, Solar neighborhood, Stars: luminosity function, mass function, Astronomy, Astrophysics, 01 natural sciences, luminosity function, mass function [Stars], Astronomi, astrofysik och kosmologi, luminosity: mass function [Stars], Astronomy, Astrophysics and Cosmology, MAIN-SEQUENCE, Hertzsprung-Russell-diagram, 010303 astronomy & astrophysics, Stars:low-mass brown-dwarfs, wide binaries, Physics, education.field_of_study, north galactic pole, Astrophysics::Instrumentation and Methods for Astrophysics, Astrometry, BROWN DWARF, Astrophysics - Solar and Stellar Astrophysics, mass function, NORTH GALACTIC POLE, Physical Sciences, symbols, CIRCULAR-VELOCITY CURVE, Halo, astro-ph.SR, Hertzsprung–Russell diagram, stars: luminosity function, astro-ph.GA, Posterior probability, Population, main-sequence, Luminosity-Function, FOS: Physical sciences, Mass-Function, Astronomy & Astrophysics, Computer Science::Digital Libraries, Photometry (optics), DWARF LUMINOSITY-FUNCTION, dwarf luminosity-function, sky-survey, symbols.namesake, Settore FIS/05 - Astronomia e Astrofisica, luminosity function [stars], low-mass [Stars], 0103 physical sciences, Stars: luminosity: mass function, Stars: low-mass, WHITE-DWARFS, education, Solar and Stellar Astrophysics (astro-ph.SR), brown dwarf, catalogs, astrometry, Hertzsprung-Russell and C-M diagrams, stars: low-mass, solar neighborhood, Astrophysics - Astrophysics of Galaxies, SKY-SURVEY, white-dwarfs, Science & Technology, 010308 nuclear & particles physics, Luminosity function, White dwarf, TRIGONOMETRIC PARALLAXES, Astronomy and Astrophysics, Low-mass, 115 Astronomy, Space science, WIDE BINARIES, Stars, Physics::History of Physics, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), solar-neighborhood, Catalogs, circular-velocity curve, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: Aims. We produce a clean and well-characterised catalogue of objects within 100 pc of the Sun from the Gaia Early Data Release 3. We characterise the catalogue through comparisons to the full data release, external catalogues, and simulations. We carry out a first analysis of the science that is possible with this sample to demonstrate its potential and best practices for its use., Methods. Theselection of objects within 100 pc from the full catalogue used selected training sets, machine-learning procedures, astrometric quantities, and solution quality indicators to determine a probability that the astrometric solution is reliable. The training set construction exploited the astrometric data, quality flags, and external photometry. For all candidates we calculated distance posterior probability densities using Bayesian procedures and mock catalogues to define priors. Any object with reliable astrometry and a non-zero probability of being within 100 pc is included in the catalogue., Results. We have produced a catalogue of 331 312 objects that we estimate contains at least 92% of stars of stellar type M9 within 100 pc of the Sun. We estimate that 9% of the stars in this catalogue probably lie outside 100 pc, but when the distance probability function is used, a correct treatment of this contamination is possible. We produced luminosity functions with a high signal-to-noise ratio for the main-sequence stars, giants, and white dwarfs. We examined in detail the Hyades cluster, the white dwarf population, and wide-binary systems and produced candidate lists for all three samples. We detected local manifestations of several streams, superclusters, and halo objects, in which we identified 12 members of Gaia Enceladus. We present the first direct parallaxes of five objects in multiple systems within 10 pc of the Sun., Conclusions. We provide the community with a large, well-characterised catalogue of objects in the solar neighbourhood. This is a primary benchmark for measuring and understanding fundamental parameters and descriptive functions in astronomy.
Published: 2021
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3. The Galactic Anticentre

Author: Vincenzo Ripepi, A. de Torres, Annie C. Robin, Mariateresa Crosta, C. Diener, L. Noval, Daniel Michalik, P. J. Richards, L. Karbevska, K. Kruszyńska, E. Fraile, André Moitinho, Michał Pawlak, P. Panuzzo, M. Riello, Benoit Carry, A. Yoldas, Harry Enke, N. Tonello, P. Gavras, M. Vaillant, Rosanna Sordo, E. del Pozo, Lorenzo Rimoldini, M. Bernet, G. Orrù, W. van Reeven, J. M. Martín-Fleitas, S. Diakite, P. Burgess, P. Osborne, Derek W. Morris, M. I. Carnerero, Amina Helmi, Mike Smith, Iain A. Steele, Alessandro Sozzetti, M. Kontizas, A. Sagristà Sellés, Roberto Molinaro, B. Holl, D. Baines, D. Molina, J. Fernández-Hernández, S. Marinoni, Michele Bellazzini, Maria Süveges, Teresa Antoja, D. Barbato, Uwe Lammers, Isabella Pagano, Davide Massari, G. Plum, P. Ramos, G. Jevardat de Fombelle, M. Biermann, C. Crowley, Mathias Schultheis, D. W. Evans, P. A. Palicio, Paolo Montegriffo, Ramachrisna Teixeira, R. Blomme, Elmé Breedt, T. A. Lister, F. A. Jansen, Ruth Carballo, Marcella Marconi, A. Abreu Aramburu, J. M. Carrasco, F. Royer, S. Accart, A. Burlacu, S. Regibo, Andrej Prsa, M. Sarasso, Nicolas Rambaux, A. F. Mulone, Ana Ulla, Eric Gosset, Alessandra Mastrobuono-Battisti, George M. Seabroke, H. E. Delgado, Federico Marocco, C. Nicolas, T. Lebzelter, Nami Mowlavi, C. Barache, Nicoletta Sanna, G. Gracia-Abril, R. Santoveña, R. Haigron, N. Unger, Silvio Leccia, A. Jean-Antoine Piccolo, A. F. Lanza, Alberto Vecchiato, Thomas Wevers, F. Figueras, G. Busso, C. Fabre, P. Di Matteo, F. Riclet, F. Solitro, Eric Slezak, N. Samaras, João Alves, Emese Plachy, Timo Prusti, F. van Leeuwen, J. Osinde, O. Marchal, M. Ajaj, C. Ducourant, Tatiana Muraveva, Shay Zucker, H. Steidelmüller, Alberto Riva, D. Semeux, N. Cheek, Laurent Galluccio, Martin A. Barstow, Alex Bombrun, S. Liao, M. van Leeuwen, R. E. de Souza, P. de Laverny, T. Roegiers, Paul J. McMillan, G. Holland, Alexey Mints, G. Giuffrida, L. M. Sarro, Juan Zorec, G. Sadowski, P. Yvard, Carme Jordi, J. L. Halbwachs, Laurent Chemin, Ludovic Delchambre, M. Garcia-Reinaldos, Ugo Becciani, Diego Bossini, Ángel Gómez, Sergi Blanco-Cuaresma, Rossella Cancelliere, C. Fabricius, J. De Ridder, L. Eyer, L. Pulone, Simon Hodgkin, Ennio Poretti, F. De Angeli, M. Haywood, E. Anglada Varela, Antonella Vallenari, F. X. Pineau, D. Garabato, A. Guerrier, H. E. P. Lindstrøm, Thomas Hilger, I. Bellas-Velidis, Frédéric Arenou, Paolo Giacobbe, Ilaria Musella, Tristan Cantat-Gaudin, L. Palaversa, Pedro García-Lario, David Hobbs, C. Turon, E. Balbinot, P. de Teodoro, Sébastien Lambert, D. Katz, Angela Bragaglia, Anthony G. A. Brown, Paolo Tanga, P. Castro Sampol, J. C. Segovia, Alejandra Recio-Blanco, Yves Fremat, Jon Marchant, Jose M Hernandez, S. Ragaini, Sofia Randich, P. Re Fiorentin, J. F. Le Campion, Gisella Clementini, M. Segol, P. David, R. Drimmel, F. Crifo, J. Guiraud, M. David, R. L. Smart, M. Fabrizio, I. Gonzalez-Santamaria, D. Eappachen, M. G. Lattanzi, Miguel García-Torres, Andreas Korn, S. Voutsinas, László Molnár, Simchon Faigler, A. Mora, Nicholas Rowell, Antti Penttilä, R. Geyer, Sanjeev Khanna, Aldo Dell'Oro, H. E. Huckle, C. Dolding, N. Leclerc, Monica Rainer, R. Mor, J. Bakker, Maroussia Roelens, Douglas J. Marshall, A. G. Butkevich, Nigel Hambly, A. Masip, Laia Casamiquela, R. Messineo, Martin Altmann, A. M. Piersimoni, Alessandro Spagna, Gerry Gilmore, Stefano Bertone, Patrick Charlot, O. Vanel, Daniel Hestroffer, Marco Castellani, Sebastian L. Hidalgo, W. Roux, Łukasz Wyrzykowski, Krzysztof A. Rybicki, M. M. S. Marcos Santos, Raphael Guerra, Alberto Cellino, E. Poggio, Gérard Jasniewicz, J. J. González-Vidal, S. Cowell, Peter G. Jonker, C. M. Raiteri, S. Bartolomé, J. Álvarez Cid-Fuentes, Elisabetta Caffau, J. J. Aguado, N. R. Millar, Ulrike Heiter, Federica Spoto, Felix Franke, A. Baudesson-Stella, M. Barros, Tsevi Mazeh, A. Panahi, E. Brugaletta, R. Buzzi, Elena Pancino, G. Altavilla, E. Racero, Enrique Solano, Mikael Granvik, Minia Manteiga, C. Robin, Tomaz Zwitter, Deborah Busonero, Alberto Krone-Martins, Marc Audard, Kevin Benson, Christos Siopis, L. Balaguer-Núñez, C. A. L. Bailer-Jones, E. Poujoulet, O. L. Creevey, E. Szegedi-Elek, C. Fouron, Michael Davidson, E. Licata, Despina Hatzidimitriou, Mark Cropper, Z. Kostrzewa-Rutkowska, S. Managau, A. Dapergolas, Sergio Messina, Laszlo Szabados, H. I. Siddiqui, W. Löffler, Mario Gai, J.-B. Delisle, Leanne P. Guy, S. G. Baker, W. J. Cooper, Alfred Castro-Ginard, Conny Aerts, A. Lorca, Xavier Luri, Damien Ségransan, Grigori Fedorets, A. Garofalo, J. Juaristi Campillo, F. De Luise, F. Pailler, F. Taris, L. Bramante, Thierry Morel, T. Cornez, L. Martin Polo, M. Ramos-Lerate, Jordi Portell, E. Salguero, Sergei A. Klioner, K. Janßen, Ulrich Bastian, Stefan Jordan, P. Esquej, A. C. Lanzafame, Beatrice Bucciarelli, C. Panem, Y. Lebreton, Carlos Dafonte, S. Girona, D. Munoz, Dimitri Pourbaix, William Thuillot, J. H. J. de Bruijne, N. Brouillet, L. Chaoul, F. Torra, Alex Lobel, J.-L. Bassilana, Francesca Fragkoudi, M. Romero-Gómez, C. A. Stephenson, T. Pauwels, Eva Sciacca, Alessandro Bressan, Morgan Fouesneau, E. Livanou, E. Gerlach, X. Peñalosa Esteller, Roberto Morbidelli, L. Rohrbasser, Johannes Sahlmann, Elisa Distefano, P. Sartoretti, Karri Muinonen, Zoltan Balog, Y. Viala, J. Torra, H. Zhao, L. Siltala, G. Tauran, D. Souami, P. Madrero Pardo, David Teyssier, Jesus Salgado, J. Souchay, C. P. Murphy, Maria-Rosa L. Cioni, N. A. Walton, S. Bouquillon, Andrea Chiavassa, Agnes Fienga, Giovanni Comoretto, F. Julbe, A. Hutton, Yassine Damerdji, Richard I. Anderson, Pierre Fernique, Céline Reylé, M. Hauser, E. Utrilla, Pierre Kervella, C. Zurbach, Robert G. Mann, Ummi Abbas, Hector Canovas, D. L. Harrison, Y. Lasne, Mark Taylor, Y. Le Fustec, E. F. del Peloso, N. Bauchet, E. van Dillen, Jan Rybizki, N. Hładczuk, T. Boch, J. González-Núñez, Carine Babusiaux, C. Pagani, Krzysztof Nienartowicz, Eduard Masana, G. Kordopatis, N. Robichon, Luciana Bianchi, R. Gutiérrez-Sánchez, Arnaud Siebert, A. Kochoska, T. Carlucci, Jérôme Berthier, J. Castañeda, D. Vicente, R. De March, A. Garcia-Gutierrez, M. Weiler, F. Thévenin, Lennart Lindegren, Isabelle Lecoeur-Taïbi, Guy Rixon, Francois Mignard, P. M. Marrese, M. A. Álvarez, Caroline Soubiran, Rene Andrae, C. Ordénovic, A. Delgado, V. Sanchez Gimenez, Ministerio de Economía y Competitividad (España), Ministerio de Ciencia, Innovación y Universidades (España), Universidad de Barcelona, Xunta de Galicia, European Commission, Centros de Excelencia Severo Ochoa, BARCELONA SUPERCOMPUTING CENTER (BSC), SEV2015-0493, Krone Martins, A. [0000-0002-2308-6623], McMillan, P. [0000-0002-8861-2620], Carrasco Martínez, J. P. [0000-0002-3029-5853], Sozzetti, A. [0000-0002-7504-365X], Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MINECO/ICTI2013-2016/MDM-2014-0369, Centrode Excelencia Científica Instituto de Ciencias del Cosmos Universidad de Barcelona, MINECO/ICTI2013-2016/SEV2015-0493, Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), National Natural Science Foundation of China (NSFC), Estonian Ministry of Education and Research, Centre National D'Etudes Spatiales (CNES), Agence Nationale de la Recherche (ANR), Centre National de la Recherche Scientifique (CNRS), European Commission (EC), European Research Council (ERC), Institut des Sciences de l'Univers (INSU), Institut National Polytechnique (INP), Institut National de Physique nucleaire et de Physique des Particules (IN2P3), Deutsches Zentrum für Luft- und Raumfahrt (DLR), Hungarian Academy of Sciences, Hungarian National Research, Development, and Innovation Office (NKFIH), Science Foundation Ireland (SFI), Israel Science Foundation (ISF), Agenzia Spaziale Italiana (ASI), Italian Istituto Nazionale di Astrofisica (INAF), Netherlands Organisation for Scientific Research (NWO), Polish National Science Centre, Ministry of Science and Higher Education (MNiSW), Fundacao para a Ciencia e a Tecnologia (FCT), Slovenian Research Agency, Agencia Estatal de Investigación (AEI), Generalitat de Catalunya, United Kingdom Science and Technology Facilities Council (STFC), United Kingdom Space Agency (UKSA), Gaia Collaboration, Universidad de Cantabria, Astronomy, Kapteyn Astronomical Institute, Institut de Ciencies del Cosmos (ICCUB), Universitat de Barcelona (UB), Joseph Louis LAGRANGE (LAGRANGE), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Kapteyn Astronomical Institute [Groningen], University of Groningen [Groningen], INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), Institut de recherches sur la catalyse et l'environnement de Lyon (IRCELYON), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), M2A 2021, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Planetary-system research, Department of Physics, Particle Physics and Astrophysics, Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Université Nice Sophia Antipolis (... - 2019) (UNS), and Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: trigonometric parallaxes, SOLAR NEIGHBORHOOD, Astronomy, SAGITTARIUS DWARF GALAXY, Astrophysics, 01 natural sciences, sagittarius dwarf galaxy, 010303 astronomy & astrophysics, Physics, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], solar neighborhood, Astrophysics::Instrumentation and Methods for Astrophysics, Astrometry, Gelexy: kinematics and dynamics, Kinematics and Dynamics, Open clusters and asssociations: individual: Berkeley 29, sky survey, Disk, Physical Sciences, kinematics and dynamics [Gelexy], old open clusters, MILKY-WAY, Astrophysics::Earth and Planetary Astrophysics, open clusters and associations: individual: Berkeley 29, Galaxy: kinematics and dynamics, disk [Galaxy], individual: Berkeley 29 [open clusters and associations], Astrometria, Berkeley 29, EXPLORING HALO SUBSTRUCTURE, LOCAL KINEMATICS, Milky Way, FOS: Physical sciences, Open Clusters and Associations, Individual, exploring halo substructure, Astrophysics::Cosmology and Extragalactic Astrophysics, Astronomy & Astrophysics, Computer Science::Digital Libraries, stellar structure, Galaxy: disk, Open clusters and associations: individual: Saurer 1, Galactic halo, Halo, Settore FIS/05 - Astronomia e Astrofisica, individual: Berkeley 29 [Open clusters and asssociations], 0103 physical sciences, distances [stars], halo [Galaxy], Disc, Stars: distances, milky-way, Saurer 1, Astrophysics::Galaxy Astrophysics, canis-major, Science & Technology, 010308 nuclear & particles physics, TRIGONOMETRIC PARALLAXES, Galaxy: halo, stars: distances, open clusters and associations: individual: Saurer 1, Astrophysics - Astrophysics of Galaxies, Astronomy and Astrophysics, Galactic plane, kinematics and dynamics [Galaxy], 115 Astronomy, Space science, CANIS-MAJOR, Stars, Galaxy, Physics::History of Physics, Estels, individual: Saurer 1 [open clusters and associations], Distances, local kinematics, OLD OPEN CLUSTERS, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), SKY SURVEY, Open cluster, STELLAR STRUCTURE
Abstract: Aims. We aim to demonstrate the scientific potential of the Gaia Early Data Release 3 (EDR3) for the study of different aspects of the Milky Way structure and evolution and we provide, at the same time, a description of several practical aspects of the data and examples of their usage., Methods. We used astrometric positions, proper motions, parallaxes, and photometry from EDR3 to select different populations and components and to calculate the distances and velocities in the direction of the anticentre. In this direction, the Gaia astrometric data alone enable the calculation of the vertical and azimuthal velocities; also, the extinction is relatively low compared to other directions in the Galactic plane. We then explore the disturbances of the current disc, the spatial and kinematical distributions of early accreted versus in situ stars, the structures in the outer parts of the disc, and the orbits of open clusters Berkeley 29 and Saurer 1., Results. With the improved astrometry and photometry of EDR3, we find that: (i) the dynamics of the Galactic disc are very complex with oscillations in the median rotation and vertical velocities as a function of radius, vertical asymmetries, and new correlations, including a bimodality with disc stars with large angular momentum moving vertically upwards from below the plane, and disc stars with slightly lower angular momentum moving preferentially downwards; (ii) we resolve the kinematic substructure (diagonal ridges) in the outer parts of the disc for the first time; (iii) the red sequence that has been associated with the proto-Galactic disc that was present at the time of the merger with Gaia-Enceladus-Sausage is currently radially concentrated up to around 14 kpc, while the blue sequence that has been associated with debris of the satellite extends beyond that; (iv) there are density structures in the outer disc, both above and below the plane, most probably related to Monoceros, the Anticentre Stream, and TriAnd, for which the Gaia data allow an exhaustive selection of candidate member stars and dynamical study; and (v) the open clusters Berkeley 29 and Saurer 1, despite being located at large distances from the Galactic centre, are on nearly circular disc-like orbits., Conclusions. Even with our simple preliminary exploration of the Gaia EDR3, we demonstrate how, once again, these data from the European Space Agency are crucial for our understanding of the different pieces of our Galaxy and their connection to its global structure and history.
Published: 2021
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4. Gaia early data release 3: summary of the contents and survey properties (Corrigendum)

Author: Mathias Schultheis, Marcella Marconi, N. Robichon, Luciana Bianchi, F. Crifo, J. Guiraud, D. Eappachen, R. Gutiérrez-Sánchez, Sanjeev Khanna, A. M. Piersimoni, Raphael Guerra, J. J. González-Vidal, J. J. Aguado, N. R. Millar, A. Baudesson-Stella, Tristan Cantat-Gaudin, Alejandra Recio-Blanco, Ummi Abbas, Francesca Figueras, R. Blomme, Elmé Breedt, G. Busso, A. Jean-Antoine Piccolo, Gerry Gilmore, A. Panahi, S. Messina, C. Babusiaux, Łukasz Wyrzykowski, Mark Taylor, Alex Bombrun, M. Barros, M. Riello, M. Ajaj, C. Ducourant, Tatiana Muraveva, Alberto Cellino, E. Poggio, Y. Le Fustec, C. P. Murphy, Maria-Rosa L. Cioni, Hector Canovas, D. L. Harrison, Y. Lasne, Elena Pancino, N. Bauchet, G. Orrù, Sergi Blanco-Cuaresma, Simon Hodgkin, Ennio Poretti, A. F. Lanza, Alberto Vecchiato, Thomas Wevers, Andrea Chiavassa, E. Szegedi-Elek, A. G. A. Brown, Laszlo Szabados, A. Masip, Laia Casamiquela, R. Messineo, C. Crowley, Alessandra Mastrobuono-Battisti, E. Poujoulet, Zoltan Balog, L. Eyer, A. Guerrier, H. E. P. Lindstrøm, Ilaria Musella, Laurent Galluccio, Martin A. Barstow, Aldo Dell'Oro, Mark Cropper, Z. Kostrzewa-Rutkowska, Angela Bragaglia, Arnaud Siebert, Damien Ségransan, A. Kochoska, J. L. Halbwachs, E. F. del Peloso, N. Hładczuk, F. Pailler, Stefan Jordan, Stefano Bertone, L. Pulone, Frédéric Arenou, Patrick Charlot, David Hobbs, P. Castro Sampol, Yves Fremat, Sofia Randich, Marc Audard, Despina Hatzidimitriou, A. Dapergolas, L. Palaversa, W. van Reeven, M. Hauser, E. Utrilla, Georges Kordopatis, Sergei A. Klioner, Alex Lobel, J.-L. Bassilana, G. Tauran, T. Prusti, H. Steidelmüller, Alberto Riva, Diego Bossini, Maria Süveges, Isabella Pagano, J. H. J. de Bruijne, Elisabetta Caffau, Federica Spoto, Felix Franke, T. Boch, M. I. Carnerero, T. Carlucci, Grigori Fedorets, J. Castañeda, W. Löffler, Enrique Solano, Paolo Montegriffo, A. Abreu Aramburu, T. Lebzelter, Nami Mowlavi, C. Barache, C. A. Stephenson, A. Lorca, L. Bramante, Amina Helmi, J.-B. Delisle, B. Holl, D. Molina, J. Fernández-Hernández, G. Jevardat de Fombelle, F. van Leeuwen, C. Robin, D. Katz, E. Gerlach, Elisa Distefano, Michele Bellazzini, P. de Laverny, G. Sadowski, Tomaz Zwitter, A. Burlacu, Teresa Antoja, Rossella Cancelliere, F. Torra, C. Pagani, Annie C. Robin, Johannes Sahlmann, Karri Muinonen, Eva Sciacca, D. Vicente, Krzysztof Nienartowicz, A. F. Mulone, Shay Zucker, Nicholas Rowell, H. E. Delgado, Dimitri Pourbaix, G. Giuffrida, H. E. Huckle, Federico Marocco, L. Noval, Daniel Michalik, P. J. Richards, Y. Viala, E. van Dillen, L. Karbevska, H. Zhao, L. Siltala, Nicoletta Sanna, K. Kruszyńska, E. Fraile, R. De March, Y. Lebreton, C. M. Raiteri, D. W. Evans, Ana Ulla, Francesca Fragkoudi, Jan Rybizki, E. Brugaletta, L. Rohrbasser, Andreas Korn, S. G. Baker, A. Garcia-Gutierrez, L. M. Sarro, R. Buzzi, T. Pauwels, Jérôme Berthier, L. Chaoul, W. J. Cooper, Eduard Masana, M. van Leeuwen, D. Garabato, P. Panuzzo, Maroussia Roelens, Benoit Carry, Deborah Busonero, Michael Davidson, J. González-Núñez, Thomas Hilger, E. Licata, M. Weiler, Mikael Granvik, Alessandro Bressan, Morgan Fouesneau, Miguel García-Torres, W. Roux, Pedro García-Lario, Iain A. Steele, P. Ramos, Alessandro Sozzetti, Roberto Molinaro, O. L. Creevey, D. Barbato, Lorenzo Rimoldini, Uwe Lammers, Alexey Mints, P. Sartoretti, E. Livanou, D. Souami, P. Madrero Pardo, David Teyssier, M. Bernet, Yassine Damerdji, X. Peñalosa Esteller, C. Fabre, F. Thévenin, Gérard Jasniewicz, Roberto Morbidelli, Jesus Salgado, Juan Zorec, Ángel Gómez, Douglas J. Marshall, A. G. Butkevich, M. Biermann, E. Racero, J. Torra, R. Gomel, O. Vanel, Daniel Hestroffer, Sebastian L. Hidalgo, P. A. Palicio, F. De Angeli, Richard L. Smart, J. M. Martín-Fleitas, Derek W. Morris, F. Royer, S. Diakite, S. Accart, C. Dolding, P. Burgess, Richard I. Anderson, A. Garofalo, I. Bellas-Velidis, George M. Seabroke, P. Osborne, Claus Fabricius, Jon Marchant, Ramachrisna Teixeira, João Alves, G. Gracia-Abril, R. Santoveña, R. Haigron, N. Unger, Lennart Lindegren, Isabelle Lecoeur-Taïbi, Paolo Giacobbe, Emese Plachy, M. Fabrizio, I. Gonzalez-Santamaria, F. Taris, Kevin Benson, Christos Siopis, M. M. S. Marcos Santos, S. Cowell, Jose M Hernandez, S. Ragaini, Jordi Portell, Linda K. Molnar, R. Drimmel, Pierre Kervella, C. Zurbach, S. Bartolomé, J. Álvarez Cid-Fuentes, E. Salguero, Ulrich Bastian, Robert G. Mann, Marco Castellani, J. Osinde, E. Balbinot, Caroline Soubiran, Rene Andrae, J. Souchay, M. G. Lattanzi, S. Voutsinas, Agnes Fienga, Giovanni Comoretto, P. Esquej, A. C. Lanzafame, Beatrice Bucciarelli, C. Panem, Carlos Dafonte, Alfred Castro-Ginard, J. C. Segovia, Monica Rainer, F. Julbe, A. Hutton, Peter G. Jonker, William Thuillot, A. de Torres, F. De Luise, Pierre Fernique, Céline Reylé, M. Kontizas, G. Plum, Martin Altmann, L. Martin Polo, M. Ramos-Lerate, P. de Teodoro, Sébastien Lambert, G. Altavilla, André Moitinho, D. Munoz, N. Brouillet, Alessandro Spagna, C. Ordénovic, Gisella Clementini, C. Nicolas, Michał Pawlak, Silvio Leccia, A. Delgado, M. Romero-Gómez, N. Cheek, A. Yoldas, Harry Enke, Rosanna Sordo, V. Sanchez Gimenez, Mike Smith, P. David, D. Baines, Paolo Tanga, Guy Rixon, Alberto Krone-Martins, S. Managau, N. A. Walton, S. Bouquillon, C. Fouron, Francois Mignard, Xavier Luri, J. Juaristi Campillo, S. Girona, Thierry Morel, T. Cornez, P. M. Marrese, M. A. Álvarez, S. Liao, Andrej Prsa, M. Sarasso, Nicolas Rambaux, Paul J. McMillan, Ludovic Delchambre, M. Garcia-Reinaldos, M. Haywood, E. Anglada Varela, Antonella Vallenari, S. Regibo, R. E. de Souza, Sahar Shahaf, J. De Ridder, M. Segol, Simchon Faigler, A. Mora, Ulrike Heiter, Carla Cacciari, Minia Manteiga, H. I. Siddiqui, Mario Gai, Leanne P. Guy, N. Leclerc, T. A. Lister, F. A. Jansen, Ruth Carballo, J. M. Carrasco, Bengt Edvardsson, P. Di Matteo, K. Janßen, F. Riclet, F. Solitro, O. Marchal, G. Holland, F. X. Pineau, C. Turon, P. Re Fiorentin, Tsevi Mazeh, Mariateresa Crosta, C. Diener, J. F. Le Campion, Vincenzo Ripepi, M. David, R. Mor, N. Tonello, E. del Pozo, J. Bakker, Davide Massari, A. Sagristà Sellés, Marco Delbo, Eric Slezak, P. Gavras, N. Samaras, S. Marinoni, M. Vaillant, J. M. Petit, P. Yvard, Carme Jordi, Ugo Becciani, Antti Penttilä, R. Geyer, Nigel Hambly, Krzysztof A. Rybicki, L. Balaguer-Núñez, C. A. L. Bailer-Jones, Conny Aerts, Eric Gosset, D. Semeux, T. Roegiers, and Laurent Chemin
Subjects: Physics, Addenda, 010504 meteorology & atmospheric sciences, Errata, Parallaxes, Astronomy, Astronomy and Astrophysics, Astrophysics, Astrometry, Photometric, 01 natural sciences, Techniques, catalogs, astrometry, parallaxes, proper motions, techniques: photometric, errata, addenda, Settore FIS/05 - Astronomia e Astrofisica, Space and Planetary Science, 0103 physical sciences, Proper motions, Catalogs, 010303 astronomy & astrophysics, Data release, 0105 earth and related environmental sciences
Abstract: We present the early installment of the third Gaia data release, Gaia EDR3, consisting of astrometry and photometry for 1.8 billion sources brighter than magnitude 21, complemented with the list of radial velocities from Gaia DR2. Gaia EDR3 contains celestial positions and the apparent brightness in G for approximately 1.8 billion sources. For 1.5 billion of those sources, parallaxes, proper motions, and the (G_BP-G_RP) colour are also available. The passbands for G, G_BP, and G_RP are provided as part of the release. For ease of use, the 7 million radial velocities from Gaia DR2 are included in this release, after the removal of a small number of spurious values. New radial velocities will appear as part of Gaia DR3. Finally, Gaia EDR3 represents an updated materialisation of the celestial reference frame (CRF) in the optical, the Gaia-CRF3, which is based solely on extragalactic sources. The creation of the source list for Gaia EDR3 includes enhancements that make it more robust with respect to high proper motion stars, and the disturbing effects of spurious and partially resolved sources. The source list is largely the same as that for Gaia DR2, but it does feature new sources and there are some notable changes. The source list will not change for Gaia DR3. Gaia EDR3 represents a significant advance over Gaia DR2, with parallax precisions increased by 30 percent, proper motion precisions increased by a factor of 2, and the systematic errors in the astrometry suppressed by 30--40 percent for the parallaxes and by a factor ~2.5 for the proper motions. The photometry also features increased precision, but above all much better homogeneity across colour, magnitude, and celestial position. A single passband for G, G_BP, and G_RP is valid over the entire magnitude and colour range, with no systematics above the 1 percent level.
Published: 2021

5. Apophis 2029: Decadal Opportunity for the Science of Planetary Defense

Author: William C. Danchi, Patrick Michel, Patrick A. Taylor, James F. Bell, Michael Marsset, Daniel J. Scheeres, Jessica M. Sunshine, Derek C. Richardson, D. Souami, William F. Bottke, Olivier S. Barnouin, J. Souchay, J. V. DeMartini, Yaeji Kim, Mirel Birlan, Terik Daly, Michael C. Nolan, Carol A. Raymond, Masatoshi Hirabayashi, Joshua T.S. Cahill, Humberto Campins, Francesca E. DeMeo, Daniel D. Durda, N. Moskovitz, Joseph A. Nuth, Donald K. Yeomans, Alex Parker, Andy Cheng, M. Brozovic, Richard P. Binzel, Ryan S. Park, Flaviane Venditti, Brent W. Barbee, P. W. Chodas, Anthony Freeman, Kim Reh, Paul Sava, Lucy F. Lim, Anne Virkki, A. C. Boley, Observatoire de Paris, Université Paris sciences et lettres (PSL), Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Namur Center for Complex Systems [Namur] (NaXys), Université de Namur [Namur] (UNamur), Systèmes de Référence Temps Espace (SYRTE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), and Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Laboratoire Lagrange, Nice, France
Subjects: [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Comet, Geosynchronous orbit, Potentially hazardous object, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Context (language use), Mars Exploration Program, Astrobiology, Jupiter, Planetary science, 13. Climate action, Asteroid, [SDU]Sciences of the Universe [physics], Environmental science, ComputingMilieux_MISCELLANEOUS
Abstract: International audience; Many advancements in planetary science are achieved by seizing upon the opportunity created by rare natural events (e.g. comet Shoemaker-Levy 9 Jupiter impact; 1994) and by planned physical interactions (e.g. Deep Impact into comet Tempel 1; 2005). A forthcoming opportunity to seize upon a natural physical “experiment” occurs on April 13, 2029 with the unprecedentedly close Earth encounter by the large 340m asteroid (99942) Apophis. On that date, nature is performing the “experiment” of subjecting the physical body of Apophis to Earth’s tidal torques as it approaches to within 31,000 km of Earth’s surface, a distance that is closer than orbiting geosynchronous satellites.A potentially hazardous asteroid (PHA) as large as Apophis encountering Earth this closely (within 0.1 lunar distances) is, on average, a once-per-thousand year event. (In context, Apophis is 7 times larger and 350 times more massive than the Tunguska 1908 impactor; 5000 times more massive than Chelyabinsk 2013.) Because of this event’s incredible rarity, knowledge gained through measurements and outcomes of the Apophis 2029 “natural experiment” are clearly a decadal, if not millennial, opportunity for planetary science. Most specifically, this knowledge opportunity is for the science supporting planetary defense. Further, on April 13, 2029 all of Earth will be watching: Apophis will be visible to the naked eye speeding across the evening sky for an estimated 2 billion people spanning western Europe and northern Africa.In this White Paper we outline our current best understanding, and uncertainties, for scientific advances in the physical study of potentially hazardous asteroids that may be achievable by measuring physical changes of Apophis’ spin, surface structure, and/or shape configuration inresponse to Earth’s tidal torques. If tidal torques themselves, or surface configuration changes induce any measurable seismic vibration signal inside Apophis, a new field of asteroid seismology has the potential to be born. Over six decades of planetary science, seismology has been achieved beyond Earth for only two planetary worlds: Moon and Mars.With this White Paper, we take no position on how to implement specific investigations capable of achieving the science advances offered by the Apophis 2029 opportunity. Instead we advocate that competitive selection of investigations, be they theoretical or observational (ground-based, space-based, or in situ), be executed under the direction of NASA’s Planetary Defense Coordination Office, with a projected and perhaps necessarily augmented budget capable of supporting them. International collaboration is strongly encouraged.Thus, summarizing in four specific points, we urge the framers of the Decadal Survey to:• Recognize the decadal, if not millennial, opportunity for the science of planetary defense presented by the Apophis 2029 once-per-thousand-year “natural experiment.”• Prioritize as a top-level planetary defense science goal modeling and measuring the physical outcome on Apophis exerted by Earth’s tidal torques so as to achieve the greatest possible new insights into the physical nature, including the internal structure, of PHAs.• Recognize that time is of the essence for defining and implementing investigations of physical effects on Apophis, particularly if in situ measurements are to be considered. An Apophis 2029 Science Definition Team may be prescribed.• Recognize that the achievable knowledge of PHAs presented by the Apophis 2029 opportunity could have immeasurable benefits to the future of humanity, in the highly unlikely, but not impossible necessity to mitigate a future impact threat
Published: 2021
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6. Gaia Early Data Release 3: Acceleration of the solar system from Gaia astrometry

Author: Vincenzo Ripepi, P. Gavras, M. Vaillant, Mathias Schultheis, László Molnár, E. Poujoulet, Mark Cropper, C. Babusiaux, D. Molina, J. Fernández-Hernández, G. Jevardat de Fombelle, A. de Torres, Aldo Dell'Oro, J. Castañeda, Z. Kostrzewa-Rutkowska, A. Bombrun, André Moitinho, Marcella Marconi, Rossella Cancelliere, M. Hauser, M. Ajaj, C. M. Raiteri, L. Eyer, Michał Pawlak, H. I. Siddiqui, C. Ducourant, Tatiana Muraveva, Tsevi Mazeh, A. Panahi, Federico Marocco, Stefano Bertone, D. Vicente, Patrick Charlot, A. Guerrier, R. De March, Mario Gai, J. Souchay, H. E. P. Lindstrøm, Nicoletta Sanna, Agnes Fienga, Giovanni Comoretto, Jon Marchant, A. Lorca, E. Utrilla, A. Garcia-Gutierrez, Ilaria Musella, L. Balaguer-Núñez, Leanne P. Guy, N. Leclerc, E. Brugaletta, A. Yoldas, Harry Enke, Rosanna Sordo, Zoltan Balog, H. E. Huckle, L. Palaversa, Monica Rainer, T. A. Lister, F. A. Jansen, Ruth Carballo, Alessandro Spagna, J. M. Carrasco, Mikael Granvik, Derek W. Morris, F. Julbe, A. Hutton, J. Osinde, D. W. Evans, M. van Leeuwen, M. Weiler, F. Thévenin, F. Torra, Iain A. Steele, Lorenzo Rimoldini, Alessandro Sozzetti, Francesca Fragkoudi, K. Janßen, O. L. Creevey, J. González-Núñez, T. Pauwels, R. Buzzi, Miguel García-Torres, S. Liao, G. Tauran, Lennart Lindegren, C. Fouron, Pierre Fernique, Céline Reylé, P. Di Matteo, E. Szegedi-Elek, F. Pailler, Stefan Jordan, Roberto Molinaro, Elisabetta Caffau, Federica Spoto, Felix Franke, D. Barbato, Isabelle Lecoeur-Taïbi, Tristan Cantat-Gaudin, Alejandra Recio-Blanco, E. Livanou, W. Roux, X. Peñalosa Esteller, P. A. Palicio, J. H. J. de Bruijne, Sergi Blanco-Cuaresma, Deborah Busonero, F. Riclet, Conny Aerts, Georges Kordopatis, Guy Rixon, F. Solitro, Davide Massari, Mike Smith, D. Baines, Roberto Morbidelli, Gerry Gilmore, G. Plum, Alexey Mints, O. Marchal, Juan Zorec, Ángel Gómez, C. A. Stephenson, Michael Davidson, C. Fabricius, E. Licata, Sergio Messina, Laszlo Szabados, M. Biermann, A. Garofalo, G. Holland, F. De Angeli, Andreas Korn, E. Anglada Varela, Grigori Fedorets, S. Girona, E. Gerlach, Antonella Vallenari, M. Riello, Łukasz Wyrzykowski, Damien Ségransan, F. Taris, L. Bramante, Alberto Cellino, S. Regibo, Andrej Prsa, M. Sarasso, E. Poggio, W. Löffler, Paolo Giacobbe, Jordi Portell, Elisa Distefano, Eric Slezak, I. Bellas-Velidis, Nicolas Rambaux, E. Balbinot, J.-B. Delisle, Maroussia Roelens, E. Salguero, P. de Teodoro, E. van Dillen, Y. Lebreton, Francois Mignard, Sergei A. Klioner, Ulrich Bastian, N. Samaras, G. Orrù, R. E. de Souza, P. Esquej, Paul J. McMillan, A. C. Lanzafame, Sébastien Lambert, Beatrice Bucciarelli, Jose M Hernandez, M. Bernet, S. Ragaini, Gisella Clementini, A. F. Mulone, Ludovic Delchambre, C. Panem, Eric Gosset, P. David, M. Garcia-Reinaldos, Ana Ulla, F. Crifo, J. Guiraud, Mariateresa Crosta, L. Chaoul, C. Diener, Carlos Dafonte, Karri Muinonen, Alex Lobel, J.-L. Bassilana, Maria Süveges, Isabella Pagano, Dimitri Pourbaix, D. Eappachen, M. Haywood, R. Drimmel, Y. Viala, S. Voutsinas, D. Semeux, William Thuillot, N. A. Walton, Paolo Montegriffo, A. Abreu Aramburu, C. Fabre, H. Zhao, Alessandro Bressan, S. Bouquillon, Sanjeev Khanna, T. Lebzelter, N. Tonello, L. Siltala, M. G. Lattanzi, C. Crowley, P. Yvard, Carme Jordi, Elena Pancino, E. del Pozo, Jan Rybizki, Nami Mowlavi, C. Barache, Morgan Fouesneau, J. De Ridder, Ugo Becciani, Martin Altmann, F. van Leeuwen, P. M. Marrese, M. A. Álvarez, A. Jean-Antoine Piccolo, A. F. Lanza, Alberto Vecchiato, Thomas Wevers, Caroline Soubiran, C. P. Murphy, A. M. Piersimoni, Alessandra Mastrobuono-Battisti, Peter G. Jonker, A. Sagristà Sellés, T. Roegiers, S. Marinoni, Johannes Sahlmann, Rene Andrae, P. Sartoretti, G. Altavilla, Raphael Guerra, F. X. Pineau, M. Segol, T. Prusti, J. J. González-Vidal, J. J. Aguado, N. R. Millar, A. Baudesson-Stella, Andrea Chiavassa, Laurent Chemin, C. Turon, H. Steidelmüller, Douglas J. Marshall, A. G. Butkevich, Alberto Riva, P. de Laverny, Simchon Faigler, Laurent Galluccio, A. Mora, P. Re Fiorentin, C. Ordénovic, J. F. Le Campion, A. Delgado, V. Sanchez Gimenez, M. David, G. Sadowski, R. L. Smart, A. Masip, Laia Casamiquela, R. Messineo, R. Mor, J. Bakker, C. Dolding, J. M. Martín-Fleitas, S. Diakite, Coryn A. L. Bailer-Jones, D. Souami, P. Madrero Pardo, Martin A. Barstow, David Teyssier, Ummi Abbas, Jesus Salgado, Paolo Tanga, A. Burlacu, O. Vanel, Ulrike Heiter, Daniel Hestroffer, Sebastian L. Hidalgo, H. E. Delgado, Alberto Krone-Martins, C. Robin, Kevin Benson, Christos Siopis, S. Managau, P. Burgess, Tomaz Zwitter, M. M. S. Marcos Santos, S. Cowell, J. L. Halbwachs, Xavier Luri, Antti Penttilä, R. Geyer, Minia Manteiga, Yassine Damerdji, Nigel Hambly, S. Bartolomé, J. Álvarez Cid-Fuentes, P. Osborne, J. Juaristi Campillo, Mark Taylor, Richard I. Anderson, Y. Le Fustec, Thierry Morel, T. Cornez, Krzysztof A. Rybicki, L. Pulone, N. Bauchet, Pierre Kervella, C. Zurbach, Alfred Castro-Ginard, Frédéric Arenou, P. Ramos, Robert G. Mann, Annie C. Robin, J. C. Segovia, M. Barros, Hector Canovas, D. L. Harrison, Y. Lasne, L. Noval, David Hobbs, E. F. del Peloso, P. Castro Sampol, Yves Fremat, F. De Luise, Daniel Michalik, P. J. Richards, L. Karbevska, N. Hładczuk, K. Kruszyńska, T. Boch, Sofia Randich, A. G. A. Brown, C. Pagani, L. Martin Polo, M. Ramos-Lerate, Krzysztof Nienartowicz, Eduard Masana, E. Racero, E. Fraile, Marc Audard, N. Robichon, Luciana Bianchi, G. Gracia-Abril, R. Santoveña, R. Haigron, N. Unger, Jérôme Berthier, Despina Hatzidimitriou, R. Gutiérrez-Sánchez, M. Fabrizio, I. Gonzalez-Santamaria, A. Dapergolas, P. Panuzzo, Benoit Carry, Francesca Figueras, R. Blomme, Elmé Breedt, D. Munoz, Diego Bossini, G. Busso, D. Katz, Simon Hodgkin, Ennio Poretti, N. Brouillet, Marco Castellani, Nicholas Rowell, Arnaud Siebert, M. Romero-Gómez, Shay Zucker, W. van Reeven, A. Kochoska, G. Giuffrida, Eva Sciacca, T. Carlucci, L. M. Sarro, M. I. Carnerero, Amina Helmi, D. Garabato, B. Holl, Michele Bellazzini, L. Rohrbasser, Teresa Antoja, J. Torra, Thomas Hilger, Pedro García-Lario, Gérard Jasniewicz, Enrique Solano, S. G. Baker, W. J. Cooper, F. Royer, S. Accart, George M. Seabroke, João Alves, Emese Plachy, C. Nicolas, Silvio Leccia, N. Cheek, Uwe Lammers, Ramachrisna Teixeira, Techniche Universtât Desden, Joseph Louis LAGRANGE (LAGRANGE), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Lund Observatory, Lund University [Lund], Zentrum für astronomie, Universität Heidelberg [Heidelberg], Department of nuclear medicine, Haukeland University Hospital, University of Bergen (UiB)-University of Bergen (UiB), Merck Serono S.A [Geneva Research Center], Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Universität Heidelberg [Heidelberg] = Heidelberg University, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Planetary-system research, Department of Physics, Particle Physics and Astrophysics, Gaia Collaboration, Unidad de Excelencia Científica María de Maeztu Instituto de Ciencias del Cosmos Universidad de Barcelona, MDM-2014-0369, Centro de Excelencia Científica Severo Ochoa, Instituto de Ciencias del Cosmos de la Universidad de Barcelona, SEV2015-0493, Deliste, J. B. [0000-0001-5844-9888], Sozzeti, A. [0000-0002-7504-365X], Forderung der wissenschaftlichen Forschung (FWF), Belgian federal Science Policy Office (BELSPO), Hertha Firnberg Programme, Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Comite Francais d'Evaluation de la Cooperation Universitaire et Scientifique avec le Bresil (COFECUB), National Natural Science Foundation of China (NSFC), China Scholarship Council (CSC), European Commission (EC), European Research Council (ERC), Hungarian National Research, Development, and Innovation Office (NKFIH), Science Foundation Ireland (SFI), Israel Science Foundation (ISF), Agenzia Spaziale Italiana (ASI), Istituto Nazionale di Astrofisica (INAF), Netherlands Research School for Astronomy (NOVA), Fundacao para a Ciencia e a Tecnologia (FCT), Agencia Estatal de Investigación (AEI), European Space Agency (ESA), Centre National D'Etudes Spatiales (CNES), Ministero dell'Istruzione, dell'Università e della Ricerca (MIUR), Narodowe Centrum Nauki (NCN), Slovenian Research Agency, Swedish National Space Agency (SNSA), United Kingdom Science and Technology Facilities Council (STFC), Universitat de Barcelona (UB), Generalitat de Catalunya, Xunta de Galicia, Universidad de Cantabria, ITA, European Commission, Ministerio de Ciencia, Innovación y Universidades (España), Ministerio de Economía y Competitividad (España), Astronomy, and Kapteyn Astronomical Institute
Subjects: Data Analysis, Solar System, Astronomy, kinematics and dynamics, virgo cluster, Astrophysics, 01 natural sciences, bar, Astronomi, astrofysik och kosmologi, large-magellanic-cloud, Methods, Astronomy, Astrophysics and Cosmology, 010303 astronomy & astrophysics, Physics, Astrophysics of Galaxies, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Astrophysics::Instrumentation and Methods for Astrophysics, Astrometry, VIRGO CLUSTER, Kinematics and Dynamics, Amplitude, kinematics, Physical Sciences, MILKY-WAY, astrometry, Galaxy: kinematics and dynamics, PROPER MOTION, Proper motion, perturbation, proper motions, reference systems, methods: data analysis, Astrophysics - Astrophysics of Galaxies, FOS: Physical sciences, Context (language use), proper motion, Astronomy & Astrophysics, MASS, Computer Science::Digital Libraries, Gravitational potential, Acceleration, Settore FIS/05 - Astronomia e Astrofisica, 0103 physical sciences, data analysis [methods], Vector spherical harmonics, KINEMATICS, distance, milky-way, Science & Technology, PERTURBATION, 010308 nuclear & particles physics, Astronomy and Astrophysics, kinematics and dynamics [Galaxy], 115 Astronomy, Space science, Physics::History of Physics, BAR, Galaxy, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), DISTANCE, mass, LARGE-MAGELLANIC-CLOUD
Abstract: Context. Gaia Early Data Release 3 (Gaia EDR3) provides accurate astrometry for about 1.6 million compact (QSO-like) extragalactic sources, 1.2 million of which have the best-quality five-parameter astrometric solutions., Aims. The proper motions of QSO-like sources are used to reveal a systematic pattern due to the acceleration of the solar systembarycentre with respect to the rest frame of the Universe. Apart from being an important scientific result by itself, the acceleration measured in this way is a good quality indicator of the Gaia astrometric solution., Methods. Theeffect of the acceleration was obtained as a part of the general expansion of the vector field of proper motions in vector spherical harmonics (VSH). Various versions of the VSH fit and various subsets of the sources were tried and compared to get the most consistent result and a realistic estimate of its uncertainty. Additional tests with the Gaia astrometric solution were used to get a better idea of the possible systematic errors in the estimate., Results. Our best estimate of the acceleration based on Gaia EDR3 is (2.32 +/- 0.16) x 10(-10) m s(-2) (or 7.33 +/- 0.51 km s(-1) Myr-1) towards alpha = 269.1 degrees +/- 5.4 degrees, delta = -31.6 degrees +/- 4.1 degrees, corresponding to a proper motion amplitude of 5.05 +/- 0.35 mu as yr(-1). This is in good agreement with the acceleration expected from current models of the Galactic gravitational potential. We expect that future Gaia data releases will provide estimates of the acceleration with uncertainties substantially below 0.1 mu as yr(-1).
Published: 2020
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7. Quasars with large proper motions: A selection from the LQAC-5 catalogue combined with Gaia EDR3

Author: J. Souchay, N. Secrest, S. Lambert, N. Zacharias, F. Taris, C. Barache, F. Arias, and V. Makarov
Subjects: Space and Planetary Science, Astronomy and Astrophysics
Abstract: Context. Thanks to the cross-identification between the Gaia EDR3 (E-Data Release 3) catalogue and the quasars’ compiled catalogue LQAC-5 (Large Quasar Astrometric Catalogue-5), accurate astrometric parameters as well as photometric measurements were available for a set of 416 113 quasars. Aims. After analysing the astrometric and photometric properties of these quasars,we concentrate our study on objects characterized by significant proper motion, which contradicts the postulate that they are fixed in the celestial sphere. Methods. We derived statistical properties of the positions, parallaxes, and proper motions of the quasars cross-matched with Gaia EDR3. We carried out a specific investigation of quasars with a proper motion larger than 10 mas yr−1, and used colour–colour diagrams in mid-infrared to discriminate these quasars from stellar contamination. We discuss, in detail, a few cases where the abnormal proper motion could be caused by misidentifications. Results. We note that 43% of LQAC-5 quasars were not detected by Gaia EDR3, mainly because of the cut-off magnitude at G = 21. The comparison between r(G) (Gaia) and r (SDSS) shows a normal distribution. The normalized distributions of parallaxes and proper motions are identical to that of the Gaia CRF2, as well as the distribution of the GBP − GRP colour index. We have identified 937 LQAC-5 objects (0.27% of the sample) with Gaia EDR3 proper motion which is significant at the 5σ level. We have clearly shown that below z = 0.35, the integrated magnitude G(r) obtained from SDSS spectra is smaller than G (Gaia), leading to the statement that the quasars are generally resolved under this threshold, which should lead to a bad determination of proper motion. Moreover, to discriminate quasars from stellar contamination, we have plotted them in a mid-infrared colour–colour diagram. Finally, we have made a final selection of 41 objects with μ > 10 mas yr−1, satisfying drastic constraints, which makes them potential candidates for considering their proper motion as real. Conclusions. In this paper we carried out a complete analysis of the quasars of the LQAC-5 which were cross-identified with Gaia EDR3 ; this serves as an alternative and complementary study with respect to Gaia CRF2, involving a different population of quasars. We selected a set of 41 quasars with a proper motion exceeding 10 mas yr−1, which can be considered as very high for objects which are a priori fixed in the celestial sphere.
Published: 2022
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8. Parsec-scale alignments of radio-optical offsets with jets in AGNs from multifrequency geodetic VLBI, Gaia EDR3, and the MOJAVE program

Author: Jia-Cheng Liu, C. Barache, F. Taris, J. Souchay, N. Liu, E. F. Arias, Zi Zhu, Sébastien Lambert, Institut national supérieur du professorat et de l'éducation - Académie de Nantes (INSPÉ Nantes), Université de Nantes (UN), and KPB BioSiences
Subjects: Astrophysics::High Energy Astrophysical Phenomena, media_common.quotation_subject, Population, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, 0103 physical sciences, Very-long-baseline interferometry, reference systems, education, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, media_common, Physics, education.field_of_study, Jet (fluid), International Celestial Reference System, 010308 nuclear & particles physics, Centroid, Astronomy and Astrophysics, Quasar, Astrometry, galaxies: jets, techniques: interferometric, Space and Planetary Science, Sky, astrometry, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: Aims. We aim to study the relative positions of quasar emission centers at different wavelengths in order to help link the various realizations of the International Celestial Reference System (ICRS), and to unveil systematic uncertainties and individual source behavior at different wavelengths. Methods. We based our study on four catalogs representing the ICRS, the ICRF3 positions in the three VLBI bands X, K, and Ka, and the Gaia EDR3 catalog in optical wavelengths. We complemented radio source positions with jet kinematics results from the MOJAVE team, allowing us to obtain jet directions on the sky. A six-parameter deformation model was used to remove systematic uncertainties present in the different catalogs. Results. For a set of 194 objects common to the four catalogs and to the objects whose jet kinematics was studied by the MOJAVE team, we computed the orientation between positions at the different wavelengths and with respect to the directions of the jets. We find that the majority of these objects have their radio-to-optical vector along the jet, with the optical centroid downstream from the radio centroids, and that the K and Ka centroids are preferably upstream in the jet with respect to the X centroid, which is consistent with the paradigm of a simple core–jet model. For a population of multiwavelength positions aligned along the jet, astrometric information can therefore be used to measure the direction of the jet independently of imaging. In addition, we find several sources for which the optical centroid coincides with stationary radio features with a relatively high fraction of polarization, indicating optical emission dominated by a synchrotron process in the jet.
Published: 2021
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9. The LQAC-4, last update of the Large Quasar Astrometric Catalogue

Author: Christophe Barache, A. H. Andrei, J. Souchay, F. Taris, B. Coelho, and C. Gattano
Subjects: Proper motion, Ideal (set theory), Space and Planetary Science, Epoch (reference date), Primary (astronomy), Computer science, Celestial coordinate system, Astronomy, Astronomy and Astrophysics, Quasar, Reference frame
Abstract: Thanks to their point-like structure and to their lack of significant proper motion, quasars represent the ideal objects for modeling quasi-inertial directions in space. For that reason the present primary conventional reference frame, the ICRF-2, is constructed from the set of the celestial coordinates of a sample of extragalactic objects, whose the very large majority are quasars. Thus any newly discovered quasar must be considered as a potential future ideal astrometric marker. Therefore compiling all the recorded quasars at a given epoch looks as a useful task. This constitutes the aim of the LQAC (Large Quasar Astrometric Catalogue). We present here the contents of the future release of this catalogue quoted as the LQAC-4, insisting on the related strategy of compilation. Preliminary results concerning the cross-identification with the Gaia DR1 catalogue are emphasized
Published: 2017
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10. A dynamical study of the Gefion asteroid family

Author: J. Souchay, Antonio F. B. A. Prado, Safwan Aljbaae, T. G. G. Chanut, FEG/UNESP, Systèmes de Référence Temps Espace (SYRTE), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Instituto Nacional de Pesquisas Espaciais (INPE), Ministério da Ciência, Tecnologia e Inovação, Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Orbital plane, 010504 meteorology & atmospheric sciences, media_common.quotation_subject, Monte Carlo method, Yarkovsky effect, Astronomy and Astrophysics, Astrophysics, Asteroid family, 01 natural sciences, Asymmetry, Celestial mechanics, Gravitation, Space and Planetary Science, Asteroid, 0103 physical sciences, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, media_common
Abstract: The Gefion asteroid family is a group of S-type asteroids located between the 8J:-3A and 5J:-2A mean-motion resonances. The 5J:-2A resonance seems to be responsible for the absence of the right side of the V-shape of this family. We aim in this work to present a detailed study on the Gefion family, motivated by the incompatibility found in previous family age estimations and the fact that this family could be seen as one of the most probable sources of L-chondrite meteorites. After eliminating all possible taxonomical and dynamical interlopers, we use a Monte Carlo method to analyze the semi-major axis evolution of several fictitious families under the influence of the Yarkovsky and Yarkovsky-O’Keefe-Radzievsky-Paddack (YORP) effects. We also perform simulations using symplectic integrators to account for the Yarkovsky effect (diurnal and seasonal versions) and the stochastic YORP effect. We make use of the distribution of the component of the ejection velocity field (vW) perpendicular to the orbital plane and the time dependence of the asymmetry of the distribution of the target function of a fictitious family generated with ejection velocity parameter 20+55−15m s−1to obtain an age estimate of 1030+19−67Myr. We find that 6.5% of asteroids from the Gefion family can reach orbits similar to particles in the current near-Earth objects space; 73% of them are among the Amors asteroids, and the remaining ones are among the Apollos. We only found 0.5% from the Gefion family reaching the Mars-crossing space.
Published: 2019
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11. Orbital stability near the (87) Sylvia system

Author: J. Souchay, Antonio F. B. A. Prado, T. G. G. Chanut, Valerio Carruba, Safwan Aljbaae, Diogo M. Sanchez, Hauke Hussmann, Universidade Estadual Paulista Júlio de Mesquita Filho = São Paulo State University (UNESP), Instituto Nacional de Pesquisas Espaciais (INPE), German Aerospace Center (DLR), Systèmes de Référence Temps Espace (SYRTE), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), INPE, Universidade Estadual Paulista (Unesp), DLR Institute of Planetary Research, and PSL Research University
Subjects: Zero-velocity curves, Astrophysics, Orbital mechanics, 01 natural sciences, Gravitation, individual: (87) Sylvia. [minor planets, asteroids], Gravitational field, Primary (astronomy), 0103 physical sciences, celestial mechanics minor planets, 010303 astronomy & astrophysics, Physics, [PHYS]Physics [physics], Spacecraft, Mass distribution, Orbital stability, Mascon gravity framework, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, business.industry, Planetengeodäsie, Astronomy and Astrophysics, celestial mechanics, Celestial mechanics, (87) Sylvia, 13. Climate action, Space and Planetary Science, Asteroid, gravitation, Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], asteroids: individual: (87) Sylvia
Abstract: Made available in DSpace on 2019-10-06T17:13:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-06-01 The main goal of our work is to study the orbital dynamics of a spacecraft near the (87) Sylvia system. Here, we consider a non-homogeneous mass distribution with a dense core inside the primary asteroid. The Mascon gravity framework using the shaped polyhedral source, from light-curve data, is chosen to calculate the gravitational field. The zero-velocity curves show four unstable equilibrium points. In the absence of any solar or other celestial body perturbations, a numerical analysis of the orbital dynamics in the potential field of Sylvia is done to delineate the region of stable and unstable motions. In our model, the motions of the two moons of Sylvia and of the spacecraft are integrated with the classical equations of motion in the body-fixed frame of reference. An orbit is considered stable if the variation of its periapsis radius does not exceed a threshold value (i.e. 6 km), and the variation of its eccentricity does not exceed 0.05, although the orientation of these orbits may change. We found that the first stable orbit is detected at a distance of 550 km from the centre of Sylvia. No collision occurs with the central body beyond 350 km. The collisions with Remus occur between 300 and 900 km, while with Romulus they occur between 900 and 1450 km. Moreover, the orbits escape from the system when the distance is smaller than 350 km. Finally, we found that the stability region around our system decreases when the initial eccentricity increases. Division of Space Mechanics and Control INPE, C.P. 515 School of Natural Sciences and Engineering São Paulo State University (UNESP) DLR Institute of Planetary Research, Rutherfordstr. 2 SYRTE Observatoire de Paris PSL Research University, 61 avenue de l'Observatoire School of Natural Sciences and Engineering São Paulo State University (UNESP)
Published: 2019
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12. LQAC-5: The fifth release of the Large Quasar Astrometric Catalogue

Author: F. Taris, Christophe Barache, D. Souami, A. H. Andrei, A. Berthereau, Nathan J. Secrest, J. Souchay, C. Gattano, B. Coelho, Systèmes de Référence Temps Espace (SYRTE), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatorio Nacional [Rio de Janeiro], Observatório do Valongo/UFRJ [Rio de Janeiro], Universidade Federal do Rio de Janeiro (UFRJ), Namur Center for Complex Systems [Namur] (NaXys), Université de Namur [Namur] (UNamur), Universidade de Aveiro, and US Naval Observatory
Subjects: Physics, [PHYS]Physics [physics], education.field_of_study, Proper motion, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, Population, Astronomy and Astrophysics, Context (language use), Quasar, Celestial sphere, Astrophysics, Astrometry, Radius, 01 natural sciences, Redshift, Space and Planetary Science, quasars: general, 0103 physical sciences, astrometry, reference systems, education, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, catalogs
Abstract: Context. In addition to their great astrophysical interest, quasars represent quasi-ideal reference objects in the celestial sphere with, a priori, a lack of significant proper motion. Since the fourth release of the Large Quasar Astrometric Catalogue (LQAC-4), a large number of quasars have been discovered, in particular those coming from the DR14Q release of the SDSS. With the advent of the Gaia Data Release 2 (DR2), it is now also possible to fold in extremely accurate quasar positions. Aims. Following the same procedure as in the previous releases of the LQAC, our aim is to compile the large majority of the recorded quasars, with their best estimated coordinates and substantial information about their physical properties such as the redshift, multi-bands apparent, and absolute magnitudes. Emphasis is given to the results of the cross-matches with the Gaia DR2 catalogue, which considerably increases the positional accuracy. Methods. New quasars from the SDSS DR14Q release were cross-matched with the precedent LQAC-4 compilation with a 1″ search radius, which leads to 149 084 objects not present in the previous LQAC-4 release. Another cross-match was done with the Gaia DR2 catalogue, which enables us to considerably improve the positioning of these objects. For the first time, parallaxes and proper motions from the DR2, when available, are added to our compilation. Furthermore, a cross-identification of the LQAC-5 with the AllWISE survey gives additional mid-infrared information for an important percentage of objects. Results. Our final catalogue, namely the LQAC-5, contains 592 809 quasars. This represents roughly a 34% increase with respect to the number of objects recorded in the LQAC-4. Among them, 398 697 objects were found in common with the Gaia DR2, within a 1″ search radius. That corresponds to 67.26% of the whole population of the compilation. Conclusion. The LQAC-5 delivers a nearly complete catalogue of spectroscopically confirmed quasars (including a small proportion of 14 126 compact AGN’s) to the astronomical community, with the aim of giving their best equatorial coordinates with respect to the ICRF2 and with exhaustive additional information. For more than 50% of the sample, these coordinates are extracted from the very recent Gaia DR2.
Published: 2019
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13. Gaia Data Release 2

Author: H. E. Huckle, F. Riclet, R. Buzzi, D. J. Marshall, Deborah Busonero, Michael Davidson, C Boeche, Sergio Messina, F. X. Pineau, G. Jasniewicz, L. Balaguer-Núñez, C. A. L. Bailer-Jones, L. Chaoul, J. L. Halbwachs, D. Teyssier, A. F. Lanza, Alberto Vecchiato, Shay Zucker, Francois Taris, Conny Aerts, L. Pulone, Mario Gai, L. M. Sarro, Frédéric Arenou, Á. L. Juhász, Alessandro Bressan, Joao Alves, Morgan Fouesneau, David Hobbs, Yves Fremat, L. Ruiz-Dern, A. Hutton, Sofia Randich, Gerry Gilmore, D. Garabato, Leanne P. Guy, J. González-Núñez, M. Weiler, H. Steidelmüller, D. de Martino, M. A. Álvarez, Vincenzo Ripepi, G. Gracia-Abril, Uwe Lammers, P. de Laverny, G. Sadowski, Nicolas Mary, Bengt Edvardsson, Laszlo Szabados, Łukasz Wyrzykowski, David Barrado, Alberto Cellino, Damien Ségransan, T Roegiers, Olivier Wertz, A. Recio-Blanco, Sergei A. Klioner, J. Durán, A. Panahi, A. Karampelas, Alex Lobel, J.-L. Bassilana, H. Voss, Sven Zschocke, A. Bombrun, F. De Angeli, Toni Santana-Ros, J. C. Segovia, D. Vicente, S. Blanco-Cuaresma, A. G. Butkevich, M. Riello, Amina Helmi, J. Bakker, J. Souchay, A. Kewley, R Alvarez, Daniel Hestroffer, Sergey E. Koposov, Tsevi Mazeh, Maria Süveges, F. F. Suess, P. Drazinos, B. Holl, H. Ziaeepour, T. Wevems, Eva Sciacca, P. Esquej, A. Gueguen, J. Heu, R. Geyer, J. Fernández-Hernández, E. Licata, Laurent Galluccio, J. Cuypers, Peter G. Jonker, Ummi Abbas, Elena Pancino, Jean Surdej, E. Anglada Varela, Michele Bellazzini, Teresa Antoja, Martin A. Barstow, László Molnár, Isabella Pagano, E. Solano, E. Brugaletta, P. Koubsky, Paolo Tanga, Alberto Krone-Martins, M. Clotet, Nigel Hambly, R. L. Smart, Paolo Giacobbe, Simchon Faigler, G. Giuffrida, Aldo Dell'Oro, Yveline Lebreton, Stefano Bertone, Mario G. Lattanzi, Paul S. Barklem, D. Tapiador, Patrick Charlot, A. H. Andrei, Luciano Nicastro, S. Managau, Lorenzo Rimoldini, Mario Di Martino, Paolo Montegriffo, A. Abreu Aramburu, O. Marchal, Marcella Marconi, K. Janßen, K. Findeisen, Xavier Luri, A. Berihuete, M. Schultheis, P. Di Matteo, R. Mor, C. Barata, A. Mora, W. van Reeven, Mikael Granvik, M. Barros, Carine Babusiaux, A. G. A. Brown, Mark Taylor, Y. Le Fustec, T. Lebzelter, Nami Mowlavi, O. L. Creevey, F. Barblan, Thierry Morel, Timo Prusti, A. Riva, S. Girona, S. Liao, Viktor Votruba, Frédéric Royer, Laurent Chemin, G. Altavilla, A. M. Piersimoni, Davide Massari, Marco Delbo, S. Diakite, V. Valette, N. Bach, H. Lenhardt, André Moitinho, Christophe Barache, S. Galleti, Michał Pawlak, A. Yoldas, Harry Enke, Rosanna Sordo, A. Jean-Antoine-Piccolo, Patrice David, Giacomo Cannizzaro, W. Löffler, J. Torra, Tristan Cantat-Gaudin, Marc Audard, D. Katz, Jose M Hernandez, Gijs Nelemans, S. Ragaini, P. Osborne, D. Terrett, A. J. Falcão, D. L. Harrison, G. Plum, R. G. Mann, Ulrike Heiter, Carla Cacciari, Gal Matijevic, J. M. Petit, A. Titarenko, Despina Hatzidimitriou, Juan Zorec, Angela Bragaglia, Nicholas Rowell, Annie C. Robin, Mario David, Tri L. Astraatmadja, Giovanni Comoretto, F. Julbe, Derek W. Morris, R. Drimmel, F. García-Sedano, A. Dapergolas, L. Noval, Mike Smith, Grigori Fedorets, H. Palacin, L. Bramante, D. Molina, Jesus Salgado, C. Dolding, M. Vaillant, Daniel Michalik, H. I. Siddiqui, Minia Manteiga, P. J. Richards, D. Barbato, A. Fonti, Raphael Guerra, J. J. González-Vidal, E. del Pozo, Mariateresa Crosta, M. Žerjal, F. Torra Clotet, C. Diener, M. Hauser, G. Walmsley, Sonia Nieto, I. Bellas-Velidis, T. Boch, Antonella Vallenari, M. Segol, S. Voutsinas, F. Leroux, A. F. Mulone, Pierre Fernique, Céline Reylé, P. Panuzzo, W. Hofmann, S. Bouquillon, F. Crifo, S. Cowell, Ana Ulla, Benoit Carry, C. Ordenovic, F. Pailler, E. Utrilla, Dimitri Pourbaix, A. Hypki, Stefan Jordan, T. Carlucci, Gráinne Costigan, Alfred Castro-Ginard, C. Fabre, C. Crowley, R. Borrachero, Sébastien Lambert, J. H. J. de Bruijne, D. W. Evans, C. Turon, T. Brüsemeister, F. De Luise, R. Haigron, Carme Jordi, G. Marschalkó, C. von Essen, C. Pagani, Katrien Kolenberg, M. van Leeuwen, N. R. Millar, Gisella Clementini, A. de Torres, Ugo Becciani, S. Marinoni, Geraldine Bourda, A. F. Silva, L. Eyer, Misha Haywood, C. Fabricius, Krzysztof Nienartowicz, Miguel García-Torres, S. Regibo, P. Gavras, Gábor Marton, Elisa Distefano, A. Guerrier, H. E. P. Lindstrøm, N. A. Walton, N. Brouillet, G. Eynard Bontemps, T. A. Lister, F. A. Jansen, Ruth Carballo, Steve Vogt, J. M. Carrasco, G. Mantelet, M. Romero-Gómez, Ramachrisna Teixeira, Kjell Eriksson, A. Kochoska, Johannes Sahlmann, Joakim Klar, R. Gutiérrez-Sánchez, Ilaria Musella, L. Palaversa, Karri Muinonen, J. M. Martín-Fleitas, T. Sagristà Sellés, Marco Castellani, Y. Viala, Laia Casamiquela, R. Messineo, Eduard Masana, R. de Souza, H. Stoev, L. Siltala, B. Frezouls, E. Szegedi-Elek, Tomaz Zwitter, G. Kordopatis, C. Ducourant, Tatiana Muraveva, P. Burgess, J. De Ridder, E. Salguero, A. Burlacu, I-C. Shih, U. Stampa, V. Icardi, Iain A. Steele, Alessandro Sozzetti, M. Kontizas, Roberto Molinaro, F. Solitro, H. E. Delgado, G. Holland, J.-B. Lavigne, Andreas Korn, M. Biermann, E. Fraile, M. Fabrizio, Francesca Figueras, R. Blomme, P. Teyssandier, Elisabetta Caffau, G. Busso, Maroussia Roelens, Maarten A. Breddels, Simon Hodgkin, Luciana Bianchi, Olivier Bienaymé, Silvio Leccia, C. Le Poncin-Lafitte, Morgan Fraser, M. Ramos-Lerate, M. Gomes, N. Cheek, J. Osinde, Jérôme Berthier, Kevin Benson, Christos Siopis, P. Balm, E. Gosset, Yassine Damerdji, Richard I. Anderson, C. Zurbach, Jonas Debosscher, G. Cocozza, William O'Mullane, Andrea Chiavassa, F.E. van Leeuwen, Diego Bossini, Federica Spoto, G. Jevardat de Fombelle, Nicoletta Sanna, J. Guiraud, G. Tauran, K. W. Smith, E. Poujoulet, Mark Cropper, Z. Kostrzewa-Rutkowska, F. Glass, J. Gerssen, Thomas Hilger, C.A. Stephenson, D. Ordóñez-Blanco, Andrej Prsa, M. Sarasso, E. Kontizas, Luciana Federici, Paul J. McMillan, Nicolas Rambaux, Ludovic Delchambre, M. Garcia-Reinaldos, T. Pauwels, M. Farràs Casas, S. Bartholomé Muñoz, E. Livanou, E. Van Hemelryck, Roberto Morbidelli, R. Kohley, A. Garofalo, Jovan Veljanoski, Jon Marchant, Jordi Portell, Ulrich Bastian, M. Lopez, Bernardino Arcay, H. Savietto, Alessandro Spagna, A. C. Lanzafame, Beatrice Bucciarelli, C. Panem, Carlos Dafonte, Y. Lasne, P. Sartoretti, E. Racero, William Thuillot, A. Gavel, J. Castañeda, Gaetano Valentini, A. Rivard, E. Poggio, N. Garralda, R. De March, S. G. Baker, S. Accart, M. Altmann, F. Filippi, George M. Seabroke, F. Thévenin, A. van Elteren, Emese Plachy, Lennart Lindegren, Isabelle Lecoeur-Taïbi, Guy Rixon, S Uzzi, M Vaschetto, Francois Mignard, E. Antiche, P. M. Marrese, N. Leclerc, Caroline Soubiran, Rene Andrae, A. Delgado, and Rossella Cancelliere
Subjects: Physics, 010504 meteorology & atmospheric sciences, Astronomy, Astronomy and Astrophysics, galaxies: dwarf, Astrophysics, Astrometry, globular clusters: general, 01 natural sciences, Settore FIS/05 - Astronomia e Astrofisica, Space and Planetary Science, 0103 physical sciences, Local Group, astrometry, High Energy Physics, Galaxy: kinematics and dynamics, astrometry, globular clusters: general, galaxies: dwarf, Local Group, errata, addenda, Galaxy: kinematics and dynamics, addenda, 010303 astronomy & astrophysics, Data release, Astrophysique, errata, 0105 earth and related environmental sciences
Abstract: 0, info:eu-repo/semantics/published
Published: 2020
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14. Changes of spin axis and rate of the asteroid (99942) Apophis during the 2029 close encounter with Earth: A constrained model

Author: Yann Herve, G. Heron, Ch. Lhotka, M. Folgueira Lopez, J. Souchay, V. Puente, Systèmes de Référence Temps Espace (SYRTE), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Seccion Departamental de Astronomia y Gesodesia, Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Angle of rotation, Physics, asteroids, 010504 meteorology & atmospheric sciences, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Astronomy and Astrophysics, Context (language use), Astrophysics, Close encounter, celestial mechanics, Geodesy, 01 natural sciences, Celestial mechanics, Flattening, Apophis, Space and Planetary Science, Asteroid, Sidereal time, 0103 physical sciences, Physics::Space Physics, Precession, minor planets, Astrophysics::Earth and Planetary Astrophysics, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract: Context. The dramatic event of the 2029 close encounter between the Earth and the asteroid Apophis on April 13 2029 at a minimum distance of 38 400 km constitutes an opportunity to make investigations about the modeling of the rotational changes of the asteroid during the event. Aims. In this paper we deepen a previous study of the rotational changes of Apophis caused by gravitational effects during the close encounter, using important constraints on initial conditions brought by new recent observational data. We also evaluate the effects of the triaxial form of the asteroid on the motion of its axis of rotation in space, as well as the modifications of the spin rate due to tidal deformation. Methods. First we used more drastic constraints for the physical and geometrical parameters of Apophis, deduced from recent observational campaigns. Second we evaluated the disturbing potential due to the Earth depending not only on the asteroid flattening, but also on the component due to its triaxiality, to deduce the equations of motion and investigate the displacement of the spin axis. Third we estimated what should be the zonal deformation of the asteroid due to the tide exerted by the Earth during the close encounter and we measured the consequences on variations of the spin rate. Results. We show that the variations of obliquity and precession in longitude of Apophis during the 2029 close encounter can reach very large values, at the level of of respectiveley 1–10° and 10–40° depending on geometrical parameters. On the contrary, effects on the spin rate should be relatively small, leading to variations of the sidereal angle of rotation not exceeding 30 s. Conclusions. The tribute of this paper is to give a constrained model of the important rotational variations of Apophis during its 2029 close encounter with the Earth.
Published: 2018
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15. DIVISION A COMMISSION 8: ASTROMETRY

Author: D. W. Evans, Valeri V. Makarov, Norbert Zacharias, J. Souchay, Stephen C. Unwin, Rama Teixeira, Anthony G. A. Brown, Li Chen, Naoteru Gouda, Aleksandr Shulga, Systèmes de Référence Temps Espace (SYRTE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Systèmes de référence célestes, Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Space and Planetary Science, General assembly, Political science, Library science, Astronomy, Astronomy and Astrophysics, Astrometry, Commission, Division (mathematics), [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: International audience; Commission 8 has regularly published triennial reports in the past and the current OC therefore voted to adopt a traditional format also for this special Legacy issue of the IAU Transactions. The outgoing President is grateful for the support of many Commission members who contributed to this report. Our contribution consists of 3 parts: 1) this introduction, providing a general overview and highlights of recent research in astrometry, 2) a summary of the astrometry business & science meeting at the 2015 IAU General Assembly, and 3) the activity report of our Commisson covering the mid-2012 to mid-2015 period.
Published: 2015
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16. Gaia Data Release 1: catalogue validation

Author: G. Giuffrida, I.-C. Shih, Amina Helmi, Angela Bragaglia, André Moitinho, Nicholas A. Walton, C. Babusiaux, H. Ziaeepour, Alberto Krone-Martins, E. Antiche, Frédéric Arenou, Céline Reylé, F. Figueras, P. M. Marrese, N. Leclerc, Xavier Luri, Caroline Soubiran, Sergi Blanco-Cuaresma, L. Ruiz-Dern, J. Souchay, M. Barros, C. Fabricius, Carme Jordi, Elena Pancino, Antonella Vallenari, Annie C. Robin, Rosine Lallement, Sébastien Lambert, Maarten A. Breddels, S. Soria, M. Romero-Gómez, K. Findeisen, G. Costigan, R. Sordo, J. Heu, Laurent Galluccio, R. Mor, C. Turon, J. M. Carrasco, S. Diakite, Tristan Cantat-Gaudin, Laurent Eyer, C. Barache, P. Sartoretti, Jovan Veljanoski, Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut de Ciènces del Cosmos (ICC), Universitat de Barcelona (UB), Kapteyn Astronomical Institute [Groningen], University of Groningen [Groningen], Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213) (UTINAM), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), Observatoire Astronomique de l'Université de Genève (ObsGE), Université de Genève (UNIGE), Institute of Astronomy [Cambridge], University of Cambridge [UK] (CAM), Systèmes de Référence Temps Espace (SYRTE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Universidade de Lisboa (ULISBOA), Leiden Observatory [Leiden], Universiteit Leiden [Leiden], Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astronomico di Roma (OAR), M2A 2017, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astrofisico di Arcetri (OAA), INAF - Osservatorio Astronomico di Bologna (OABO), Université de Genève = University of Geneva (UNIGE), Universidade de Lisboa = University of Lisbon (ULISBOA), Universiteit Leiden, Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Astronomy
Subjects: Cúmuls de galàxies, 010504 meteorology & atmospheric sciences, Astrometria, Computer science, FOS: Physical sciences, Paral·laxi, computer.software_genre, 01 natural sciences, astrometry, parallaxes, proper motions, methods: data analysis, surveys, catalogs, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Astrophysics of Galaxies, Astrophysics - Solar and Stellar Astrophysics, proper motions, surveys, 0103 physical sciences, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Parallax, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, Clusters of galaxies, Astronomy and Astrophysics, Astrometry, Galaxies, methods: data analysis, Astrophysics - Astrophysics of Galaxies, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Galàxies, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), parallaxes, astrometry, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], Data mining, Astrophysics - Instrumentation and Methods for Astrophysics, Data release, computer, catalogs
Abstract: Before the publication of the Gaia Catalogue, the contents of the first data release have undergone multiple dedicated validation tests. These tests aim at analysing in-depth the Catalogue content to detect anomalies, individual problems in specific objects or in overall statistical properties, either to filter them before the public release, or to describe the different caveats of the release for an optimal exploitation of the data. Dedicated methods using either Gaia internal data, external catalogues or models have been developed for the validation processes. They are testing normal stars as well as various populations like open or globular clusters, double stars, variable stars, quasars. Properties of coverage, accuracy and precision of the data are provided by the numerous tests presented here and jointly analysed to assess the data release content. This independent validation confirms the quality of the published data, Gaia DR1 being the most precise all-sky astrometric and photometric catalogue to-date. However, several limitations in terms of completeness, astrometric and photometric quality are identified and described. Figures describing the relevant properties of the release are shown and the testing activities carried out validating the user interfaces are also described. A particular emphasis is made on the statistical use of the data in scientific exploitation., Comment: 34 pages, 52 figures, 3 tables. Submitted to A&A on Oct. 14 as part of the Gaia DR1 special issue, accepted with minor revisions on Dec. 19
Published: 2017
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17. The dynamical environment of asteroid 21 Lutetia according to different internal models

Author: J. Souchay, T. G. G. Chanut, A. Amarante, Valerio Carruba, Safwan Aljbaae, Antonio F. B. A. Prado, Systèmes de Référence Temps Espace (SYRTE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Universidade Estadual Paulista (Unesp), UPMC Univ Paris 06, INPE, FEG/UNESP, Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Instituto Nacional de Pesquisas Espaciais (INPE), and Ministério da Ciência, Tecnologia e Inovação
Subjects: 010504 meteorology & atmospheric sciences, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], FOS: Physical sciences, Geometry, 01 natural sciences, Displacement (vector), Gravitational field, Position (vector), 0103 physical sciences, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Earth and Planetary Astrophysics (astro-ph.EP), Physics, Plane (geometry), Astronomy and Astrophysics, celestial mechanics, Celestial mechanics, Classical mechanics, Space and Planetary Science, Asteroid, gravitation, Orbital motion, minor planets, asteroids: individual: (21) Lutetia, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], individual: (21) Lutetia [minor planets, asteroids], Astrophysics - Earth and Planetary Astrophysics, Numerical stability
Abstract: One of the most accurate models currently used to represent the gravity field of irregular bodies is the polyhedral approach. In this model, the mass of the body is assumed to be homogeneous, which may not be true for a real object. The main goal of the present paper is to study the dynamical effects induced by three different internal structures (uniform, three- and four-layers) of asteroid (21) Lutetia, an object that recent results from space probe suggest being at least partially differentiated. The Mascon gravity approach used in the present work, consists of dividing each tetrahedron into eight parts to calculate the gravitational field around the asteroid. The zero-velocity curves show that the greatest displacement of the equilibrium points occurs in the position of the E4 point for the four-layers structure and the smallest one occurs in the position of the E3 point for the three-layers structure. Moreover, stability against impact shows that the planar limit gets slightly closer to the body with the four-layered structure. We then investigated the stability of orbital motion in the equatorial plane of (21) Lutetia and propose numerical stability criteria to map the region of stable motions. Layered structures could stabilize orbits that were unstable in the homogeneous model., Comment: 10 pages, 7 figures, and 4 Tables. Accepted for publication in MNRAS
Published: 2016
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18. Long-term R and V -band monitoring of some suitable targets for the link between ICRF and the future Gaia celestial reference frame

Author: J. Roland, A. H. Andrei, F. Taris, J. Souchay, Frédéric Vachier, Alain Klotz, Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174) (FEMTO-ST), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS), Systèmes de Référence Temps Espace (SYRTE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Centre d'étude spatiale des rayonnements (CESR), Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, [PHYS]Physics [physics], 010308 nuclear & particles physics, Astronomy, Astronomy and Astrophysics, Quasar, Context (language use), Astrometry, Astrophysics, 01 natural sciences, Binary black hole, 13. Climate action, Space and Planetary Science, Position (vector), 0103 physical sciences, International Celestial Reference Frame, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, Barycentric celestial reference system, Reference frame
Abstract: Context. The Gaia astrometric mission of the European Space Agency was launched on December 2013. It will provide a catalog of 500 000 quasars. Some of these targets will be chosen to build an optical reference system that will be linked to the International Celestial Reference Frame (ICRF). The astrometric coordinates of these sources will have roughly the same uncertainty at both optical and radio wavelengths, and it is then mandatory to observe a common set of targets to build the link. In the ICRF, some targets have been chosen because of their pointlikeness. They are quoted as defining sources, and they ensure very good uncertainty about their astrometric coordinates. At optical wavelengths, a comparable uncertainty could be achieved for targets that do not exhibit strong astrophysical phenomena, which is a potential source of photocenter flickering. A signature of these phenomena is a magnitude variation at optical wavelengths.Aims. The goal of this work is to present the time series of 14 targets suitable for the link between the ICRF and the future Gaia Celestial Reference Frame. The observations have been done systematically by robotic telescopes in France and Chile once every two nights since 2011 and in two filters. These time series are analyzed to search for periodic or quasi-periodic phenomena that must be taken into account when computing the uncertainty about the astrometric coordinates.Methods. Two independent methods were used in this work to analyze the time series. We used the CLEAN algorithm to compare the frequency obtained to those given by the Lomb-Scargle method. It avoids misinterpreting the frequency peaks given in the periodograms.Results. For the 14 targets we determine some periods with a confidence level above 90% in each case. Some of the periods found in this work were not previously known. For the others, we did a comparative study of the periods previously studied by others and always confirm their values. All the periods given by the two methods are in good agreement with the difference always below 7.9% in the worst case. Finally we also present the structure functions for our two sets of objects (BL Lac and Seyfert galaxies).Conclusions. For all but one target, we find variations that could be the signature of periodic or quasi-periodic phenomena. Our time series could allow to bring some constraints on astrophysical models that could explain such variations. Binary black hole system, instabilities in the jet or in the accretion disk, changes in the torus structure are some of these astrophysical phenomena. They must be kept in mind when evaluating the uncertainty about the astrometric position of the targets suitable for the link between reference systems in a conservative way.
Published: 2016
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19. Variability of extragalactic sources: its contribution to the link between ICRF and the future Gaia Celestial Reference Frame

Author: Alain Klotz, A. H. Andrei, F. Taris, G. Damljanovic, Frédéric Vachier, J. Souchay, Systèmes de Référence Temps Espace (SYRTE), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Systèmes de référence célestes, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Belgrade Astronomical Observatory, Grupo de Estudos em Astronomia - Observatorio Nacional/MCT e Observatorio do Valongo/UFRJ (GEA), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Université Fédérale Toulouse Midi-Pyrénées-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Astéroïdes, comètes, météores et éphémérides (ACME), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174) (FEMTO-ST), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Centre d'étude spatiale des rayonnements (CESR), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS), Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), and Université Fédérale Toulouse Midi-Pyrénées
Subjects: [PHYS]Physics [physics], Physics, 010504 meteorology & atmospheric sciences, Astronomy and Astrophysics, Context (language use), Quasar, Astrophysics, 01 natural sciences, Atomic clock, Time variance, Space and Planetary Science, 0103 physical sciences, Magnitude (astronomy), International Celestial Reference Frame, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, Noise (radio), 0105 earth and related environmental sciences, Reference frame
Abstract: Context. The first release of the Gaia catalog is available since 14 September 2016. It is a first step in the realization of the future Gaia reference frame. This reference frame will be materialized by the optical positions of the sources and will be compared with and linked to the International Celestial Reference Frame, materialized by the radio position of extragalactic sources. Aim. As in the radio domain, it can be reasonably postulated that quasar optical flux variations can alert us to potential changes in the source structure. These changes could have important implications for the position of the target photocenters (together with the evolution in time of these centers) and in parallel have consequences for the link of the reference systems.Methods. A set of nine optical telescopes was used to monitor the magnitude variations, often at the same time as Gaia, thanks to the Gaia Observation Forecast Tool. The Allan variances, which are statistical tools widely used in the atomic time and frequency community, are introduced.Results. This work describes the magnitude variations of 47 targets that are suitable for the link between reference systems. We also report on some implications for the Gaia catalog. For 95% of the observed targets, new information about their variability is reported. In the case of some targets that are well observed by the TAROT telescopes, the Allan time variance shows that the longest averaging period of the magnitudes is in the range 20−70 d. The observation period by Gaia for a single target largely exceeds these values, which might be a problem when the magnitude variations exhibit flicker or random walk noises. Preliminary computations show that if the coordinates of the targets studied in this paper were affected by a white-phase noise with a formal uncertainty of about 1 mas (due to astrophysical processes that are put in evidence by the magnitude variations of the sources), it would affect the precision of the link at the level of 50 μas.
Published: 2018
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20. Gravity field and solar component of the precession rate and nutation coefficients of Comet 67P/Churyumov–Gerasimenko

Author: Christoph Lhotka, J. Souchay, Stefan Reimond, Oliver Baur, Systèmes de Référence Temps Espace (SYRTE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, Comet, FOS: Physical sciences, Rotation, 01 natural sciences, Gravitational field, Comet nucleus, 0103 physical sciences, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Physics, Earth and Planetary Astrophysics (astro-ph.EP), [PHYS]Physics [physics], Nutation, Astronomy and Astrophysics, Moment of inertia, Classical mechanics, Space and Planetary Science, Quantum electrodynamics, Moment (physics), Physics::Space Physics, Precession, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Earth and Planetary Astrophysics
Abstract: The aim of this study is first to determine the gravity field of the comet 67P Churyumov-Gerasimenko and second to derive the solar component of the precession rate and nutation coefficients of the spin axis of the comet nucleus, i.e. without the direct, usually larger, effect of outgassing. The gravity field, and related moments of inertia, are obtained from two polyhedra, that are provided by the OSIRIS and NAV-CAM experiments on Rosetta, and are based on the assumption of uniform density for the comet nucleus. We also calculate the forced precession rate as well as the nutation coefficients on the basis of Kinoshita's theory of rotation of the rigid Earth and adapted it to be able to indirectly include the effect of outgassing on the rotational parameters. The 2nd degree denormalized Stokes coefficients of comet 67P C-G turn out to be (bracketed numbers refer to second shape model) C20 = -6.74 [-7.93] * 10^-2, C22 = 2.60 [2.71] * 10^-2 consistent with normalized principal moments of inertia A/MR^2 = 0.13 [0.11], B/MR^2 = 0.23 [0.22], with polar moment c = C/MR^2 = 0.25, depending on the choice of the polyhedron model. The obliquity between the rotation axis and the mean orbit normal is 52 degree, and the precession rate only due to solar torques becomes 20-30 "/y. Oscillations in longitude caused by the gravitational pull of the Sun turn out to be of the order of 1', oscillations in obliquity can be estimated to be of the order of 0.5'., Comment: 9 pages, 5 figures, 4 tables, last version before publication in Monthly Notices of the Royal Astronomical Society http://mnras.oxfordjournals.org/content/455/4/3588.abstract
Published: 2015
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21. Some correlations between earthquakes and Earth tides

Author: J. Souchay and M. Stavinschi
Subjects: geography, Geophysics, geography.geographical_feature_category, Geology, Earth (chemistry), Building and Construction, Fault (geology), Rotation, Reciprocal, Seismology
Abstract: The ways by which earthquakes could influence the Earth’s rotation and, in a reciprocal way, the Earth tides could possibly trigger earthquakes have been investigated by many authors for more than one century. After summarizing studies ranging among the most prominent ones on the topic, we present an example of statistical results related to tide-earthquakes correlations starting from a database concerning a specific seismic area, the Vrancea fault located in Romania.
Published: 2003
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22. [Untitled]

Author: J. Souchay, Hiroshi Kinoshita, and S. Bouquillon
Subjects: Physics, Angular momentum, Angular displacement, Applied Mathematics, Rotation around a fixed axis, Rotational transition, Astronomy and Astrophysics, Orbital eccentricity, Cassini's laws, Computational Mathematics, symbols.namesake, Mean motion, Classical mechanics, Space and Planetary Science, Modeling and Simulation, Physics::Space Physics, symbols, Astrophysics::Earth and Planetary Astrophysics, Hamiltonian (quantum mechanics), Mathematical Physics
Abstract: We investigate the Cassini's laws which describe the rotational motion in a 1:1 spin-orbit resonance. When this rotational motion follows the conventional Cassini's laws, the figure axis coincides with the angular momentum axis. In this case we underline the differences between the rotational Hamiltonian for a 'slow rotating' body like the Moon and for a 'fast rotating' body like Phobos. Then, we study a more realistic rotational Hamiltonian where the angle J between the figure axis and the angular momentum axis could be different from zero. This Hamiltonian has not been studied before. We have found a new particular solution for this Hamiltonian which could be seen as an extension of the Cassini's laws. In this new solution the angle J is constant, which is not zero, and the precession of the angular momentum plane is equal to the mean motion of the argument of pericenter of the rotating body. This type of rotational motion is only possible when the orbital eccentricity of the rotating body is not zero. This new law enables describing in particular, the Moon mean rotational motion for which the mean value of the angle J is found to be equal to 103.9±0.7 s of arc.
Published: 2003
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23. Rigid-Earth Nutation Models

Author: J. Souchay
Subjects: Physics, Nutation, Rigidity (psychology), Rotation, Rigid body, Ephemeris, Geodesy, Flattening, Physics::Geophysics, Quality (physics), Classical mechanics, Physics::Space Physics, Precession, Astrophysics::Earth and Planetary Astrophysics
Abstract: Despite the fact that the main causes of the differences between the observed Earth nutation and that derived from analytical calculations come from geophysical effects associated with nonrigidity (core flattening, core-mantle interactions, oceans, etc.), efforts have been made recently to compute the nutation of the Earth when it is considered to be a rigid body, giving birth to several "rigid Earth nutation models." The reason for these efforts is that any coefficient of nutation for a realistic Earth (including effects due to nonrigidity) is calculated starting from a coefficient for a rigid-Earth model, using a frequency-dependent transfer function. Therefore, it is important to achieve high quality in the determination of rigid-Earth nutation coefficients to isolate the nonrigid effects that are still not well-modeled. After reviewing various rigid-Earth nutation models that have been established recently, and their relative improvement with respect to older ones, the authors discuss their specifics and their degree of agreement. Sections discuss the following: evolution of the rigid-Earth nutation theory in the 1990s, new developments in rigid-Earth nutation theory, the effects on nutation of the non-zonal harmonics of the third and fourth degree, the sub-microarcsecond rigid-Earth nutation series REN 2000, and the diurnal and sub-diurnal nutations of REN 2000.
Published: 2000
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24. Towards sub-microarsecond rigid Earth nutation series in the Hamiltonian theory

Author: J. Souchay and M. Folgueira
Subjects: Physics, Interferometry, Classical mechanics, Nutation, Harmonics, Physics::Space Physics, Very-long-baseline interferometry, Inner core, Astrophysics::Earth and Planetary Astrophysics, Ephemeris, Transfer function, Hamiltonian (control theory), Physics::Geophysics
Abstract: The nonrigid Earth nutation series adopted by the International Astronomical Union (IAU) are based on the works of Kinoshita (1977) and Wahr (1979). In Kinoshita's work, the rigid Earth nutation series were calculated by the application of the Hamiltonian canonical equations to the rotation of the rigid and elliptical Earth. In Wahr's work, the transfer function for the nutations of an elliptical, elastic, and oceanless Earth with fluid core and a solid inner core was obtained. The nonrigid Earth nutation coefficients were derived from the convolution between Wahr's transfer function and Kinoshita's rigid Earth nutation series. The improvement in the accuracy of measurement techniques, such as Very Long Baseline Interferometry (VLBI), Lunar Laser Ranging (LLR), and Global Positioning System (GPS), has led in this decade to the extension of Kinoshita's theory and more precise determination of Wahr's transfer function. In this paper, and starting from Kinoshita's work (1977), the authors present the different steps carried out during this last decade to obtain the sub-microarcsecond rigid Earth nutation series REN 2000 from the Hamiltonian study of the rotation of a rigid Earth (Souchay et al., 1999). Sections discuss the following topics: the first second-order theory of the rotation of a rigid Earth, new developments in rigid Earth nutation theory, the effects on nutation of the non-zonal harmonics of third and fourth degree, the sub-microarcsecond rigid Earth nutation series REN 20006, and the diurnal and sub-diurnal nutations of REN 2000.
Published: 2000
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25. Influence of the largest asteroids on the orbital motions of terrestrial planets: application to the Earth and Mars

Author: A. Nedelcu, J. Souchay, D. Gauchez, Systèmes de Référence Temps Espace (SYRTE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Systèmes de référence célestes, Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Astronomical Institute of the Romanian Academy, Bucharest, Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Near-Earth object, Astronomy, Astronomy and Astrophysics, Astrobiology, Space and Planetary Science, Planet, Asteroid, Physics::Space Physics, Terrestrial planet, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Protoplanet, Orbit determination, Planetary mass, Heliocentric orbit
Abstract: International audience; The level of precision of modern numerical ephemeris of the Solar System necessitates taking into account the gravitational influence of the largest asteroids on the terrestrial planets. This can be done in a straightforward manner when assuming that the mass of the asteroid is well known. Nevertheless, this is rarely the case, even for the largest asteroids. In this paper, we use recent determinations of the masses of Ceres, Pallas, and Vesta to both qualitatively and quantitatively determine the action of these asteroids on the orbital parameters of the Earth and Mars. This is done by the numerical integration by comparing the orbital motions of the perturbed planet when adding or not the perturbing asteroid to the classical 9 bodies problem (the Sun + the eight planets). Some preliminary results are discussed.
Published: 2009
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26. DIVISION I / COMMISSION 8 / WORKING GROUP DENSIFICATION OF THE OPTICAL REFERENCE FRAME

Author: C. Ducourant, Thomas E. Corbin, Imants Platais, J. Souchay, Norbert Zacharias, Ralph A. Gaume, William F. van Altena, Brian D. Mason, Beatrice Bucciarelli, Sean E. Urban, David G. Monet, Irina I. Kumkova, Francois Mignard, Jose L. Muinos Haro, D. W. Evans, Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire aquitain des sciences de l'univers (OASU), Instituto de Astronomia, Geofísica e Ciências Atmosféricas [São Paulo] (IAG), Universidade de São Paulo (USP), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), and Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Astronomy and Astrophysics, Quasar, Astrophysics, Division (mathematics), 01 natural sciences, Stars, Geography, 13. Climate action, Space and Planetary Science, Primary (astronomy), Limiting magnitude, 0103 physical sciences, International Celestial Reference Frame, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Reference frame, Barycentric celestial reference system
Abstract: A continuation of this WG was voted for at the IAU GA 2006 in Prague. The International Celestial Reference Frame (ICRF) is defined by the positions of 212 distant quasars at radio wavelengths. The primary, optical reference frame is the Hipparcos Celestial Reference Frame (HCRF), which is the Hipparcos Catalog without astrometric ‘problem’ stars (in: H. Rickman (ed.) 2001, Proceedings IAU XXIV General Assembly, Transactions IAU XXIVB (San Francisco: ASP), Resolution B1.2). The Tycho-2 catalog with its 2.5 million brightest stars forms the first step in the densification of the optical reference frame. However, the limiting magnitude of about V = 12 of the Tycho-2 catalog is not sufficient for most applications in astronomy and the goal of this IAU Working Group is to further extend the grid of highly accurate positions and motions toward more and fainter stars. The web site of this WG is at .
Published: 2008
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27. Comparisons of the REN-2000 Tables with Numerical Integration and Other Recent Analytic Tables

Author: J. Souchay
Subjects: Physics, Series (mathematics), Space and Planetary Science, Quantum mechanics, Stellar dynamics, Nutation, Mathematical analysis, Astronomy and Astrophysics, Celestial mechanics, Standard deviation, Numerical integration
Abstract: We present a comparison of the nutation given by the new REN-2000 analytic tables of Souchay et al. (for a rigid-Earth model) with that obtained from a numerical integration. We show that the standard deviation in the residuals are about 5 μas for both Δψ sin 0 and Δ, given a 134 yr time span. We also compare the nutation given by the REN-2000 series with that obtained by Roosbeek & Dehant (RDAN97) and Bretagnon et al. (BRS97). The agreement with Bretagnon et al. concerning the nutation for the figure axis is very satisfactory, with no difference exceeding 1 μas for individual coefficients of nutation, both in Δψ sin and Δ, except for the 18.6 yr component and the month component, for which the difference is a few microarcseconds. We show that the only substantial difference between REN-2000 and BRS97, concerning the 18.6 yr component, is a result of the different choice of the value of the dynamical ellipticity Hd. Moreover, comparison of the REN-2000 series with the RDAN97 series yields larger residuals than comparison with the BRS97 series. On the other hand, these residuals are noticeably smaller for the global contribution of the Oppolzer terms.
Published: 1998
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28. [Untitled]

Author: F. Arias, D. Gambis, Bruce A. Buffett, Juan Getino, Sergei A. Klioner, Thomas A. Herring, S. D. Petrov, F. Roosbeek, Joy Williams, X. Moisson, J. Souchay, David A. Salstein, Rui M. Ponte, Patrick T. Wallace, Michael Soffel, P. Bretagnon, S.Y. Zhu, Pascale Defraigne, Nicole Capitaine, Jan Vondrák, Aleksander Brzeziński, K. Seidelmann, Véronique Dehant, Renee Weber, C. Bizouard, P. M. Mathews, Vladimir Zharov, Harald Schuh, Ya. S. Yatskiv, Alessandro M. Forte, H. Fliegel, M. Feissel, H. Kinoshita, Dennis D. McCarthy, O. de Viron, John Wahr, and Richard S. Gross
Subjects: Physics, Applied Mathematics, Nutation, Astronomy and Astrophysics, Geophysics, Geodesy, Transfer function, Physics::Geophysics, Atmosphere, Computational Mathematics, Space and Planetary Science, Modeling and Simulation, Frequency domain, Physics::Space Physics, Very-long-baseline interferometry, Precession, Astrophysics::Earth and Planetary Astrophysics, Mathematical Physics, Earth (classical element), Earth's rotation
Abstract: This paper presents the reflections of the Working Group of which the tasks were to examine the non-rigid Earth nutation theory. To this aim, six different levels have been identified: Level 1 concerns the input model (giving profiles of the Earth's density and theological properties) for the calculation of the Earth's transfer function of Level 2; Level 2 concerns the integration inside the Earth in order to obtain the Earth's transfer function for the nutations at different frequencies; Level 3 concerns the rigid Earth nutations; Level 4 examines the convolution (products in the frequency domain) between the Earth's nutation transfer function obtained in Level 2, and the rigid Earth nutation (obtained in Level 3). This is for an Earth without ocean and atmosphere; Level 5 concerns the effects of the atmosphere and the oceans on the precession, obliquity rate, and nutations; Level 6 concerns the comparison with the VLBI observations, of the theoretical results obtained in Level 4, corrected for the effects obtained in Level 5.
Published: 1998
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29. A catalogue of the observations of the mutual phenomena of the Galilean satellites made in 1991 during the PHEMU91 campaign

Author: H. J. J. Bulder, J. J. Sacre, C. Ruatti, B. Morando, J. Vidal, J. M. Gomez-Forrellad, F. Sevre, T. Flatres, J. F. Mellilo, J. M. Desbats, A. Piersimoni, J. C. Le Floch, J. Arsenijevic, A. Dipaolantonio, F. Colas, V. Turcu, D. Hube, D. T. Vu, R. Burchi, O. Gherega, Y. Ito, J. Lecacheux, G. de Angelis, H. Takami, G. Oprescu, D. Przewozny, G. de Benedetto, D. Chis, B. Nitschelm, Patrice Bouchet, J. Colin, A. Mallama, Ricard Casas, G. Montignac, W. Thuillot, J. Barroso, V. Shkodrov, G. White, J. F. Le Campion, V. D'Ambrosio, F. Chauvet, M. Rapaport, J. Bourgeois, O. Hainaut, L. Farcas, J. E. Arlot, C. Blanco, C. Bauer, B. Nicolet, J. A. Cano, J. Guarro, A. Horvat, R. Taylor, B. E. Martin, H. Denzau, Mark R. Kidger, J. Souchay, J. Berthier, D. J. Tholen, M. Froeschle, A. Dumitrescu, V. Protitch-Benishek, R. Baptista, M. Federspiel, R. P. Wilds, S. Molau, A. Riou, G. Helmer, P. Descamps, R. Vasundhara, and C. Meyer
Subjects: Physics, Telescope, Jupiter, symbols.namesake, law, symbols, General Physics and Astronomy, Astronomy, Astrophysics, Astrometry, Galilean moons, law.invention
Abstract: In this paper, all the light-curves obtained during the PHEMU91 campaign of observations of the mutual phenomena of the Galilean satellites are presented. These observations give accurate astrometric positions of major interest for dynamical studies of the motion of the Galilean satellites. The aim of this work is to give obser- vational data directly usable for theoretical studies. We made 374 observations of 111 mutual events from 56 sites. The corresponding data are given in this paper 1 . The accu- racy of each observation has been deduced from a compar- ison with the theoretical predictions. For each observation, information is given about the telescope, the receptor, the site and the observational conditions.
Published: 1997
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30. Could the energy near the FCN and the FICN be explained by luni-solar or atmospheric forcing?

Author: M. Feissel, Pascale Defraigne, F. Roosbeek, Véronique Dehant, and J. Souchay
Subjects: Physics, Atmospheric pressure, Frequency band, Nutation, Inner core, Resonance, Geophysics, Outer core, Physics::Geophysics, Computational physics, Geochemistry and Petrology, Normal mode, Physics::Space Physics, Precession, Astrophysics::Earth and Planetary Astrophysics
Abstract: SUMMARY The observed time-series of precession/nutation show residuals with respect to an empirical model based on the rigid Earth theoretical nutations and a frequency dependent transfer function with resonances to the Earth's normal modes. These residuals display energy mainly in the frequency domain around 430 and 500 days in the inertial frame. In this frequency band, the energy is possibly related to two normalmode frequencies: the free core nutation (FCN) and the free inner core nutation (FICN). In this paper, we examine the possibility of obtaining this energy from the resonance effect induced by a luni-solar (or planetary) forcing, or by an atmospheric forcing at a frequency very close to these Earth free nutations. The amplification factor due to the resonance is computed from an analytical formula expressed in the case of a simplified three-layer ellipsoidal rotating earth (with an elastic inner core, a liquid outer core and an elastic mantle), as well as the empirical formula based on the analysis of VLBI observations. For the tidal forcing, the theoretical results do not show any resonance at the level of precision we have examined but it is still possible to find one frequency near the FCN or FICN frequencies which could be excited. In contrast, for the atmospheric pressure the level of energy needed could be obtained from the diurnal pressure, depending on the noise level of the Earth's global pressure. We also show that the combination of three waves can explain the observed decrease of energy with time. While the tidal potential amplitudes are too small, a pressure noise level of 0.5 Pa would be sufficient to excite these waves.
Published: 1997
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31. Agreements and Disagreements between Theories of Rigid Earth Nutation

Author: J. Souchay
Abstract: The necessity to elaborate a theory of nutation and precession matching the accuracy of very modern techniques as Very Long Baseline Interferometry and Lunar Laser Ranging led recently to various works. We discuss here the good agreement between those related to the nutation when considering the Earth as a solid body. In comparison we show the uncertainty concerning the modelisation of the transfer function leading to theoretical determination of the nutation coefficients when including dominant geophysical characteristics.
Published: 1997
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32. Precession and Nutations of Mars calculated with Kinoshita’s Model

Author: S. Bouquillon and J. Souchay
Subjects: Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics
Abstract: This paper presents the theoretical study of precession and nutation of Mars in a rigourous way. For this work we choose a natural reference system, based on the concept of non-rotating origin, and the appropriate canonical variables. Then, we solve the equations of the problem by taking into account the effects of the Sun, the Earth, Jupiter, and satellites of Mars, Phobos and Deimos.
Published: 1997
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33. Optical monitoring of extragalactic sources for linking the ICRF and the future Gaia celestial reference frame. I. Variability of ICRF sources

Author: David Coward, R. Côte, F. Taris, S. Bouquillon, A. H. Andrei, Sonia Anton, G. Bourda, Frédéric Vachier, J. Souchay, Alain Klotz, S. Lambert, Systèmes de Référence Temps Espace (SYRTE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174) (FEMTO-ST), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Erosion torrentielle neige et avalanches (UR ETGR (ETNA)), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Faculdade de Ciências da Universidade do Porto (FCUP), Universidade do Porto = University of Porto, M2A 2013, Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Universidade do Porto, Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Franche-Comté (UFC)-Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Technologie de Belfort-Montbeliard (UTBM), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), and Faculdade de Ciências da Universidade do Porto
Subjects: Physics, [PHYS.ASTR.IM]Physics [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, Context (language use), Astrometry, Astrophysics, Light curve, 01 natural sciences, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Variable (computer science), Space and Planetary Science, quasars: general, 0103 physical sciences, International Celestial Reference Frame, astrometry, Satellite, reference systems, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Reference frame, Radio wave
Abstract: International audience; Context. The astrometric mission Gaia of the European Space Agency is scheduled to be launched in 2013. It will provide an astrometric catalog of 500 000 extragalactic sources that could be the basis of a new optical reference frame after the Hipparcos satellite one. On the other hand, the current International Celestial Reference Frame (ICRF) is based on observations of extragalactic sources at radio wavelength. The astrometric coordinates of sources in these two reference systems will have roughly the same uncertainty. It is then mandatory to observe a set of common targets at both optical and radio wavelengths to link the ICRF with what could be called the Gaia Celestial Reference Frame (GCRF). Aims: The goal of this work is to observe a first set of 70 extragalactic sources at optical wavelengths that could achieve the link with the ICRF. Variations in the light curves of these targets are connected with astrophysical processes that could produce displacements of the optical photocenter. Such displacements, if they exist, are critical in the framework of the link of reference systems. Methods: Four telescopes were used to observe the targets at optical wavelengths. Two of them are located in France, one in Chile, and the last one in Australia. First observations were carried out during one year and a half in the R and V bands. A new method of characterizing the compactness of the targets was applied to the images obtained. Results: This paper presents results for the optical monitoring of extragalactic sources suitable for linking reference systems. We show that a large number of targets in our set are variable at the two observational wavelengths. A short presentation of each object is given, along with some references to earlier photometric studies. A morphological index is defined and applied to the 5000 images obtained during the observation campaign. Conclusions: This work fits into a more general project of astrophotometric and astrophysical studies of extragalactic radiosources in the framework of the reference systems. It brings to the astrometric community some information at optical wavelengths about a set of targets that could be used for the link between the radio ICRF and the future GCRF. Table 4 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/552/A98
Published: 2013
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34. Precise modeling of nutation and VLBI observations

Author: J. Souchay, M. Feissel, and Chopo Ma
Subjects: Physics, Classical mechanics, Transformation (function), Series (mathematics), Basis (linear algebra), Nutation, Very-long-baseline interferometry, General Physics and Astronomy, Astronomy, Geodetic datum, Geodesy, Interpretation (model theory)
Abstract: Using geodetic and astrometric VLBI acquired between 1984-1994, we have determined coefficients in the nutation series with uncertainties of 10 microarcseconds. This level of accuracy is quite sufficient to differentiate between alternate theories of nutation. We show that small terms predicted using the Kinoshita & Souchay (1990) rigid Earth theory of nutation revised by Souchay & Kinoshita (1995), agree well with the VLBI results at periods where the non rigid Earth corrections are reliable. These terms are different or absent from the Kinoshita (1977) theory that is the basis for the standard IAU 1980 model. We propose a nutation series based on the Kinoshita & Souchay theory using the Wahr (1979) transformation for a non rigid Earth that can be useful where the physical interpretation of the smaller terms is important. This series, called VKSNRE95.1, includes corrections to the nine largest terms derived from VLBI observations.
Published: 1996
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35. New series of rigid and non rigid Earth nutation. Comparison with observations

Author: J. Souchay
Subjects: Physics, Series (mathematics), Nutation, Earth (chemistry), Geophysics, Geodesy
Abstract: After analysing the recent developments of the theory of the nutation for a simplified rigid Earth model (Kinoshita and Souchay, 1990) with new corrections and new contributions (Williams, 1994; Souchay and Kinoshita, 1996), we will study the effect of these developments on the calculation of the coefficients of nutation for a non rigid Earth model, based on the transfer function given by Wahr (1979). The relative improvements characterized by the residuals with the observations are explained in the following.
Published: 1996
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36. From Milliarcsecond Proper Motions to the Discovery of Dark Matter: Some Winning Cards still in the hands of Photographic Astronomy

Author: J. Guibert and J. Souchay
Subjects: Physics, Dark matter, Astronomy, General Medicine, Astrophysics
Abstract: The large field of Schmidt plates allows monitoring of hundreds of thousands or even millions of stars, either for magnitude variations or for proper motions. CCD cameras benefit from the sensitivity, linearity, and easy interface to computers of detectors of increasing dimensions. However, especially for proper motion studies, there is no substitute to plates of first or intermediate epochs. In addition, the photographic plates, with their large sky coverage free of gaps, are irreplaceable for the accurate astrometry of optical counterparts of sources detected at other wavelengths.We first introduce the subject by mentioning a few problems concerning the replacement of Schmidt plates by CCD detectors. After a brief survey of astronomical applications requiring accurate astrometry or massive processing in large fields, we develop in more detail the results obtained in proper motion studies by several groups using the MAMA system (Berger et al. 1991). The last part of this paper is devoted to the studies of stellar variability and to the EROS and DUO microlensing programmes. Our conclusion (not a surprise, we think), is that Schmidt telescopes with photographic facilities should remain available to the general astronomical community for at least a decade and probably more.
Published: 1995
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37. Proper Motion Survey in the Pleiades

Author: J. Souchay and E. Schilbach
Subjects: Physics, Proper motion, Astronomy, Pleiades
Abstract: As a first step of our open cluster programme a catalogue of proper motions and photographic U, B, V, R magnitudes for stars up to 18 mag within a region centered near Alcyone is presented. The catalogue is based on MAMA measurements of plates taken with Tautenburg and OCA (CERGA) Schmidt telescopes. The photometric survey includes ca. 65000 stars and covers a total field of about 25 square degrees. Proper motions have been obtained for ca. 40000 stars within a central 17 square degree region of this field. For the majority of stars in the survey an accuracy of 0.08 mag and 2 mas/year has been estimated for photometric data and proper motions, respectively. The results of the determination of the Pleiades membership up to 18th magnitude is presented.
Published: 1995
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38. Recent Results of the Nutation Theory for a Rigid Earth

Author: H. Kinoshita and J. Souchay
Subjects: Physics, Earth model, Classical mechanics, Nutation, Frame (networking), Earth (chemistry), Mechanics
Abstract: Although the main questions remaining in the frame of the study of the nutation-precession phenomena concern principally the effects due to physical interactions, recent works have shown that even in the simplified case of a rigid Earth model of nutation, important changes have to be taken into account. Here we present the various steps having led to a more complete and more accurate rigid Earth nutation theory, since the pionnier work of Woolard (1953), insisting on the most recent improvements.
Published: 1995
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39. Dynamics of Small Solar System Bodies and Exoplanets

Author: Rudolf Dvorak and Jean J. Souchay
Subjects: Physics, Astrophysics and Astronomy, Solar System, Astronomy, Astrometry, Exoplanet, law.invention, Astrobiology, Telescope, Asteroid, law, Space Science, Orbit determination, Reference frame
Abstract: The Gaia space mission to be operated in early 2012 by the European Space Agency (ESA), will make a huge step in our knowledge of the Sun's neighbor-hood, up to the Magellanic clouds. Somewhat closer, Gaia will also provide ma jor improvements in the science of asteroids, and more generally to our Solar System, either directly or indirectly. Gaia is a scanning survey telescope aimed to perform high accuracy astrometry and photometry. More speciﬁcally it will provide physical and dynamical characterization of asteroids, a better knowledge of the solar system composition, formation and evolution, local test of the general relativity, and linking the dynamical reference frame to the kinematical ICRS. We develop here the general aspects of asteroid observations and the scientiﬁc harvest in perspective of what was achieved in the pre-Gaia era. In this lecture we focus on the determination of size of asteroids, shape and rotation, taxonomy, orbits and their improvements with historical highlight, and also the dynamical model in general.
Published: 2010
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40. Comparison of new nutation series with numerical integration

Author: H. Kinoshita and J. Souchay
Subjects: Angular momentum, Series (mathematics), Applied Mathematics, Nutation, Mathematical analysis, Equations of motion, Astronomy and Astrophysics, Geodesy, Numerical integration, Computational Mathematics, Runge–Kutta methods, Space and Planetary Science, Modeling and Simulation, Longitude, Mathematical Physics, Mathematics, Earth's rotation
Abstract: To check the results given by the new tables of the nutation for the rigid Earth model in (Kinoshita and Souchay, 1990), we perform a calculation of this nutation by numerical integration, using the basic equations of Kinoshita (1977). Results show very small long period residuals, with a discrepancy of 0.06 mas sin Ω in longitude, -0.04 mas cos Ω in obliquity, without out-of-phase components. Moreover, the total residuals of short period do not exceed 0.1 mas in longitude, 0.06 mas in obliquity. All these results are considerably better than those found by previous numerical integrations, thus confirming the validity of the new tables.
Published: 1991
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41. Dynamics of Small Solar System Bodies and Exoplanets

Author: Jean J. Souchay, Rudolf Dvorak, Jean J. Souchay, and Rudolf Dvorak
Subjects: Planetary science, Astrophysics, Mathematical physics, Solar system, Dynamical systems
Abstract: This book on recent investigations of the dynamics of celestial bodies in the solar and extra-Solar System is based on the elaborated lecture notes of a thematic school on the topic, held as a result of cooperation between the SYRTE Department of Paris Observatory and the section of astronomy of the Vienna University. Each chapter corresponds to a lecture of several hours given by its author(s). The book therefore represents a necessary and very precious document for teachers, students, and researchers in the?eld. The?rst two chapters by A. Lemaˆ?tre and H. Skokos deal with standard topics of celestial mechanics: the?rst one explains the basic principles of resonances in mechanics and their studies in the case of the Solar System. The differences between the various cases of resonance (mean motion, secular, etc.) are emphasized together with resonant effects on celestial bodies moving around the Sun. The second one deals with approximative methods of describing chaos. These methods, some of them being classical, as the Lyapounov exponents, other ones being developed in the very recent past, are explained in full detail. The second one explains the basic principles of resonances in mechanics and their studies in the case of the Solar System. The differences between the various cases of resonance (mean motion, s- ular, etc.) are emphasized together with resonant effects on celestial bodies moving around the Sun. The following three chapters by A. Cellino, by P. Robutel and J.
Published: 2010

42. The Results of the Reconstruction of the Coefficients of the Nutation for the Rigid Earth Model and Their Comparison With Numerical Integration

Author: J. Souchay and H. Kinoshita
Abstract: In view of the present accuracy of the astrometric observations and of the development of the theory of the nutation, it became necessary to make a complete revision of this theory for a rigid Earth model. We present the results of our recent one (Kinoshita and Souchay, 1989), which includes planetary effects and second order effects no considered in the previous tables (Kinoshita, 1977). We analyze the difference between these tables and the new ones providing from the revision above and the comparison between the theory and numerical integrations recently performed (Kubo and Fukushima, 1987; Shastok et al., 1987; Shastok et al., 1989). The results of this comparison are much better after revision than before.
Published: 1990
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43. Asteroid astrometry as a link between ICRF and the Dynamical Reference Frames

Author: Petre Popescu, M. Birlan, D. A. Nedelcu, Petre Paraschiv, J. Souchay, Octavian Badescu, Astronomical Institute of the Romanian Academy, Bucharest, Systèmes de Référence Temps Espace (SYRTE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Jin, W. J., Platais, I., Perryman, and M. A. C.
Subjects: QSOS, Physics, Frame (networking), Astronomy, Astronomy and Astrophysics, Astrometry, Astrophysics, Ephemeris, Space and Planetary Science, Asteroid, International Celestial Reference Frame, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Barycentric celestial reference system, Reference frame
Abstract: Highly accurate astrometry of asteroids in the frame of QSOs will provide the direct link between the Dynamical Reference Frame and the International Celestial Reference Frame. We propose a procedure that implies a selection of events for asteroids with accurately determined orbits crossing the CCD field containing the selected quasars. For asteroid ephemerides, a numerical integration method coupled with precise modelling of asteroid brightness will be used for analyzing our observations. A list of predictions for this type of “close approaches” will be presented.
Published: 2007
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44. A Large Proper Motion Survey of the Pleiades Cluster

Author: E. Aleshkina and J. Souchay
Subjects: Proper motion, Computer science, Cluster (physics), Astrophysics, Pleiades, Open cluster, Membership probability
Published: 2006
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45. Cross-identifications and astro-photometric comparisons of the ICRF with recent catalogs of quasars

Author: J. Souchay, Christophe Barache, A. M. Gontier, Systèmes de Référence Temps Espace (SYRTE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Systèmes de référence célestes, Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Space and Planetary Science, Primary (astronomy), Sky, media_common.quotation_subject, Astronomy, Astronomy and Astrophysics, Quasar, Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Redshift, media_common, Reference frame
Abstract: International audience; The ICRF represents the most accurate astrometric catalog that is the primary reference frame adopted by the IAU General Assembly at Kyoto in 1997. Despite its importance, an exhaustive study of both the sky coverage and the physical properties of the extragalactic sources representing the ICRF is lacking. The object of the present paper is to extract some information concerning these sources and cross-identify them with the data gathered by Véron-Cetty & Véron (2003, A&A, 412, 399), which is the largest compilation of various catalogs of quasars. After this cross-identification of the sources, we carry out a study of some general features of the ICRF concerning the visual magnitudes, the redshifts, and the flux at radio wavelengths
Published: 2006
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46. Dynamics of Extended Celestial Bodies and Rings

Author: Jean J Souchay
Subjects: Physics, Astrophysics and Astronomy, Classical mechanics, Current (mathematics), Gravitational field, Asteroid, Physics::Space Physics, Dynamics (mechanics), Astrophysics::Earth and Planetary Astrophysics, Deformation (meteorology), Rotation, Spinning, Tidal locking
Abstract: Spinning Bodies: A Tutorial.- Physics of the Earth's Interior, Deformation and Rotation.- Modelling and Characterizing the Earth's Gravity Field: From Basic Principles to Current Purposes.- Asteroids from Observations to Models.- Modelling Collisions Between Asteroids: From Laboratory Experiments to Numerical Simulations.- Geometric Conditions for Quasi-Collisions in opik's Theory.- The Synchronous Rotation of the Moon.- The Spin-Orbit Rotation of Mercury.- Dynamics of Planetary Rings.
Published: 2006
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47. Milli-Arcsecond Proper Motions in the Pleiades

Author: E. Schilbach, J. Guibert, and J. Souchay
Abstract: As a first step in our open cluster programme, a preliminary catalogue of proper motions and photographic B, V magnitudes for stars up to 18 mag within a region centred near Alcyone is presented. The catalogue is based on MAMA measurements of plates taken with the Tautenburg Schmidt telescope. A preliminary survey includes approx. 20,000 stars and covers a total field of about 9 square degrees. For stars brighter than B = 18 mag an accuracy of 0.05 mag and 2.5 mas/year has been estimated for photometric data and proper motions, respectively. The results of the determination of the Pleiades membership up to magnitude 18 are presented
Published: 1994
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48. Inter-Comparisons between Numerical Integrations and Analytical Theory for the Solar System

Author: D. Gauchez, M. Fouchard, and J. Souchay
Subjects: Solar System, Computer science, Integrator, CPU time, Applied mathematics, Richardson extrapolation, Eccentricity (mathematics)
Abstract: Firstly we carry out the comparison of the precision evolution with respect to cpu time of integrators applied to the two-body problem with increasing eccentricity. The integrators used in this part are: The Runge-Kutta-Nystrom method RKN12(10), Radau and Bulirsch-Stoer.
Published: 2002
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49. A new model of Mars rotation from Pathfinder data

Author: J. Souchay, S. Bouquillon, Systèmes de Référence Temps Espace (SYRTE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Henrard, J., Ferraz-Mello, and S.
Subjects: Physics, Nutation, Mars pathfinder, Mars Exploration Program, Geodesy, Moons of Mars, symbols.namesake, Pathfinder, Radio tracking, Planet, Physics::Space Physics, symbols, Astrophysics::Earth and Planetary Astrophysics, Hamiltonian (quantum mechanics), [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: International audience; Following efforts to construct an accurate modelisation of Mars rotation starting from canonical equations in an hamiltonian theoretical frame (Bouquillon and Souchay, 1996), we use recent results from radio tracking data of the Mars Pathfinder mission (Folkner et al.,1997) to modelize in the best way the motion of precession and nutation of the planet. A complete set of coefficients related to these two motions is presented, including the main effect due to the Sun and also those due to the two satellites Phobos and Deimos as well as to the planets. Moreover, Oppolzer terms are included, and their calculations explained.
Published: 1998

50. Recent Results of the Nutation Theory for a Rigid Earth

Author: J. Souchay and H. Kinoshita
Published: 1995
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