A5059430464- Geophysics and Gravity Measurements
- Astronomical Observations and Instrumentation
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Stellar, planetary, and galactic studies
- Planetary Science and Exploration
- Solar and Space Plasma Dynamics
- Geomagnetism and Paleomagnetism Studies
- Scientific Research and Discoveries
- Gamma-ray bursts and supernovae
- Galaxies: Formation, Evolution, Phenomena
- GNSS positioning and interference
- History and Developments in Astronomy
- Historical Astronomy and Related Studies
- Inertial Sensor and Navigation
- Radio Astronomy Observations and Technology
- Statistical and numerical algorithms
- Astrophysical Phenomena and Observations
- Spacecraft Dynamics and Control
- Calibration and Measurement Techniques
- Astrophysics and Star Formation Studies
- Isotope Analysis in Ecology
- earthquake and tectonic studies
- Astrophysics and Cosmic Phenomena
- Advanced Frequency and Time Standards
Centre National de la Recherche Scientifique
2015-2024
Systèmes de Référence Temps-Espace
2015-2024
Sorbonne Université
2015-2024
Université Paris Sciences et Lettres
2015-2024
Observatoire de Paris
2010-2024
Moscow State University
2020
Max Planck Society
2018
Federal Agency for Cartography and Geodesy
2015
Janssen (Switzerland)
2009
European Southern Observatory
2009
Before the publication of Gaia Catalogue, contents first data release have undergone multiple dedicated validation tests. These tests aim at analysing in-depth Catalogue content to detect anomalies, individual problems in specific objects or overall statistical properties, either filter them before public release, describe different caveats for an optimal exploitation data. Dedicated methods using internal data, external catalogues models been developed processes. They are testing normal...
We present the second realization of International Celestial Reference Frame (ICRF2) at radio wavelengths using nearly 30 years Very Long Baseline Interferometry observations.ICRF2 contains precise positions 3414 compact astronomical objects and has a positional noise floor ∼40 μas directional stability frame axes ∼10 μas.A set 295 new "defining" sources was selected on basis lack extensive intrinsic source structure.The these defining their more uniform sky distribution eliminates two...
Context. The dynamics of solar system objects, such as dwarf planets and asteroids, has become a well-established field celestial mechanics in the past thirty years, owing to improvements that have been made observational techniques numerical studies. In general, ecliptic is taken reference plane these studies, although there no dynamical reason for doing so. contrast, invariable originally defined by Laplace, seems be far more natural choice. this context, latest study dates back Burkhardt.
Context. From an astrometric point of view, quasars constitute quasi-ideal reference objects in the celestial sphere, with a priori absence proper motion. Since second release Large Quasar Astrometric Catalog (LQAC), large number have been discovered, particular upcoming new SDSS catalog.
We present here the new tables REN-2000 of nutation for a rigid Earth model, starting from Hamiltonian theory, with level truncature at individual coefficients instead (Kinoshita & Souchay 1990). For this presentation to be achieved we first carry out calculations second-order effects due crossed-nutations and spin-orbit coupling, same truncation as above. This paper is third last one in frame complete reconstruction theory nutation. It complementary part previous studies concerning...
Context. Thanks to the cross-identification between Gaia EDR3 (E-Data Release 3) catalogue and quasars’ compiled LQAC-5 (Large Quasar Astrometric Catalogue-5), accurate astrometric parameters as well photometric measurements were available for a set of 416 113 quasars. Aims. After analysing properties these quasars,we concentrate our study on objects characterized by significant proper motion, which contradicts postulate that they are fixed in celestial sphere. Methods. We derived...
The large number and all-sky distribution of quasars from different surveys, along with their presence in large, deep astrometric catalogs,enables the building an optical materialization ICRS following its defining principles. Namely: that it is kinematically non-rotating respect to ensemble distant extragalactic objects; aligned mean equator dynamical equinox J2000; realized by a list adopted coordinates extragalatic sources. Starting updated presumably complete LQAC QSOs, initial positions...
Context. Since the first release of LQAC (Large Quasar Astrometric Catalogue) a large number quasars have been discovered through very dense observational surveys. As these objects constitute cornerstones modern astrometry by indicating quasi inertial directions, their spatial density and astrometric quality must be studied in detail.
One of the most accurate models currently used to represent gravity field irregular bodies is polyhedral approach. In this model, mass body assumed be homogeneous, which may not true for a real object. The main goal present paper study dynamical effects induced by three different internal structures (uniform, three- and four-layers) asteroid (21) Lutetia, an object that recent results from space probe suggest being at least partially differentiated. Mascon approach in work, consists dividing...
Context . The dramatic event of the 2029 close encounter between Earth and asteroid Apophis on April 13 at a minimum distance 38 400 km constitutes an opportunity to make investigations about modeling rotational changes during event. Aims In this paper we deepen previous study caused by gravitational effects encounter, using important constraints initial conditions brought new recent observational data. We also evaluate triaxial form motion its axis rotation in space, as well modifications...
% context heading (optional) {Thanks to the Venus Express Mission, new data on properties of could be obtained in particular concerning its rotation.} aims (mandatory) {In view these upcoming results, purpose this paper is determine and compare major physical processes influencing rotation Venus, more particularly angular rate.} methods {Applying models already used for Earth, effect triaxiality a rigid period are computed. Then variations caused by elasticity, atmosphere core planet...
Context. The close approach of the asteroid (99942) Apophis to Earth on April 13, 2029, at a distance about 38 330 km, is naturally considered dramatic and fascinating event by astronomical community, as well public.
Context. In addition to their great astrophysical interest, quasars represent quasi-ideal reference objects in the celestial sphere with, a priori, lack of significant proper motion. Since fourth release Large Quasar Astrometric Catalogue (LQAC-4), large number have been discovered, particular those coming from DR14Q SDSS. With advent Gaia Data Release 2 (DR2), it is now also possible fold extremely accurate quasar positions. Aims. Following same procedure as previous releases LQAC, our aim...
The aim of this study is first to determine the gravity field comet 67P/Churyumov–Gerasimenko and second derive solar component precession rate nutation coefficients spin-axis nucleus, i.e. without direct, usually larger, effect outgassing. related moments inertia are obtained from two polyhedra, which provided by Optical, Spectroscopic, Infrared Remote Imaging System (OSIRIS) NAVigation CAMera (NAVCAM) experiments on Rosetta, based assumption uniform density for nucleus. We also calculate...
Aims. We aim to study the relative positions of quasar emission centers at different wavelengths in order help link various realizations International Celestial Reference System (ICRS), and unveil systematic uncertainties individual source behavior wavelengths. Methods. based our on four catalogs representing ICRS, ICRF3 three VLBI bands X , K Ka Gaia EDR3 catalog optical complemented radio with jet kinematics results from MOJAVE team, allowing us obtain directions sky. A six-parameter...
Context. The astrometric mission Gaia of the European Space Agency is scheduled to be launched in 2013. It will provide an catalog 500 000 extragalactic sources that could basis a new optical reference frame after Hipparcos satellite one. On other hand, current International Celestial Reference Frame (ICRF) based on observations at radio wavelength. coordinates these two systems have roughly same uncertainty. then mandatory observe set common targets both and wavelengths link ICRF with what...