INPOP08, a 4-D planetary ephemeris: From asteroid and time-scale computations to ESA Mars Express and Venus Express contributions

📝 Abstract

The latest version of the planetary ephemerides developed at the Paris Observatory and at the Besancon Observatory is presented here. INPOP08 is a 4-dimension ephemeris since it provides to users positions and velocities of planets and the relation between TT and TDB. Investigations leading to improve the modeling of asteroids are described as well as the new sets of observations used for the fit of INPOP08. New observations provided by the European Space Agency (ESA) deduced from the tracking of the Mars Express (MEX) and Venus Express (VEX) missions are presented as well as the normal point deduced from the Cassini mission. We show the huge impact brought by these observations in the fit of INPOP08, especially in terms of Venus, Saturn and Earth-Moon barycenter orbits.

💡 Analysis

The latest version of the planetary ephemerides developed at the Paris Observatory and at the Besancon Observatory is presented here. INPOP08 is a 4-dimension ephemeris since it provides to users positions and velocities of planets and the relation between TT and TDB. Investigations leading to improve the modeling of asteroids are described as well as the new sets of observations used for the fit of INPOP08. New observations provided by the European Space Agency (ESA) deduced from the tracking of the Mars Express (MEX) and Venus Express (VEX) missions are presented as well as the normal point deduced from the Cassini mission. We show the huge impact brought by these observations in the fit of INPOP08, especially in terms of Venus, Saturn and Earth-Moon barycenter orbits.

📄 Content

arXiv:0906.2860v2 [astro-ph.EP] 26 Aug 2009 Astronomy & Astrophysics manuscript no. inpop08.3.wbf November 6, 2018 (DOI: will be inserted by hand later) INPOP08, a 4-D planetary ephemeris: From asteroid and time-scale computations to ESA Mars Express and Venus Express contributions. A. Fienga1,2, J. Laskar1, T. Morley3, H. Manche1, P. Kuchynka1, C. Le Poncin-Lafitte4, F. Budnik3, M. Gastineau1, and L. Somenzi1,2 1 Astronomie et Syst`emes Dynamiques, IMCCE-CNRS UMR8028, 77 Av. Denfert-Rochereau, 75014 Paris, France 2 Observatoire de Besan¸con, CNRS UMR6213, 41bis Av. de l’Observatoire, 25000 Besan¸con, France 3 ESOC, Robert-Bosch-Str. 5, Darmstadt, D-64293 Germany 4 SYRTE, CNRS UMR8630, Observatoire de Paris, 77 Av. Denfert-Rochereau, 75014 Paris, France November 6, 2018 Abstract. The latest version of the planetary ephemerides developed at the Paris Observatory and at the Besan¸con Observatory is presented here. INPOP08 is a 4-dimension ephemeris since it provides to users positions and velocities of planets and the relation between TT and TDB. Investigations leading to improve the modeling of asteroids are described as well as the new sets of observations used for the fit of INPOP08. New observations provided by the European Space Agency (ESA) deduced from the tracking of the Mars Express (MEX) and Venus Express (VEX) missions are presented as well as the normal point deduced from the Cassini mission. We show the huge impact brought by these observations in the fit of INPOP08, especially in terms of Venus, Saturn and Earth-Moon barycenter orbits. Key words. celestial mechanics - ephemerides

1. Introduction Since the first release, INPOP06, of the plane- tary ephemerides developed at Paris and Besan¸con Observatories, (Fienga et al. 2008, www.imcce.fr/inpop) , several improvements have been conducted on the dynam- ical modeling of the INPOP ephemeris. The observation dataset has also been substantially increased, especially with the addition of ranging data from the ESA space missions Mars Express and Venus Express. The resulting new version of INPOP planetary ephemerides, INPOP08, is presented here with the description of its new features. The INPOP08 ephemeris has also been fitted to all avail- able Lunar Laser Ranging data (Manche et al., 2007). One of the novelties present in INPOP08 is the ad- dition, in the distribution of the ephemeris, of a time scale transformation TT-TDB that is coherent with the ephemeris. The basic idea is to provide to users po- sitions and velocities of Solar System celestial objects, and also, time ephemerides relating the Terrestrial time- scale, TT, and the time argument of INPOP, the so-called Barycentric Dynamical Time TDB, based on the defini- tion adopted by the International Astronomical Union in Send offprint requests to: A. Fienga, fienga@imcce.fr
2. Such a release of planet and time ephemerides enable us to go towards four-dimensional planetary ephemerides. Section 2 describes the INPOP procedure for the compu- tation of the TT-TDB relation. Section 3 is devoted to a brief account of the new con- straints and modeling implemented in INPOP for the as- teroid perturbations. As in INPOP06, 300 asteroids are included in the dynamical equations of INPOP08, and the remaining ones are modelized as a ring. With respect to INPOP06, the ring model and the asteroid selection have been improved, and the precise description of these ad- vances are made in (Kuchynka et al, 2009). An important part of the new observations used for the INPOP08 fit consists in the tracking data provided by the ESA space missions Mars Express and Venus Express (Morley 2006a, 2007a, 2007b). These datasets are the first radio ranging data provided by ESA, and their acquisition and reduction process is described in section 4. VEX ob- servations bring a very important set of informations on Venus orbit. It is especially of interest since this orbit is much less perturbed by asteroids than Mars and therefore has greater potential for precise ephemeris motion, funda- mental physics testing and reference frame establishment. 2 Fienga et al: INPOP08, a 4-D planetary ephemeris The section 5 deals with the INPOP fit obtained by comparisons between the dynamical modeling and the ob- servations. In this process, 34 asteroid masses were fit- ted against only 5 in INPOP06. Comparisons are made between obtained asteroid masses and other published masses. Values for the fitted Earth-Moon barycenter and Sun oblateness J2 are also given. We have also fitted the AU and comparisons are provided with the latest deter- minations of DE414 (Standish 2006; Konopliv et al. 2006) and DE421 (Folkner 2008). In addition, we have performed as well a second fit, where the AU is given the IERS Conventions 2003 value (IERS03), and the Solar GM is deduced. On several occasions, for planned high precision ob- servations, we had some enquiries about the real accu- racy of the position or velocities given by the plane- tary ephemerides. This is act

This content is AI-processed based on ArXiv data.