New constraints on Saturn's interior from Cassini astrometric data

This work has been supported by the European Community’s Seventh Framework Program (FP7/2007-2013) under grant agreement 263466 for the FP7-ESPaCE project, the International Space Science Institute (ISSI), PNP (INSU/CNES) and AS GRAM (INSU/CNES/INP). The work of R. A. J. was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. N.C. and C.M. were supported by the UK Science and Technology Facilities Council (Grant No. ST/M001202/1) and are grateful to them for financial assistance. C.M. is also grateful to the Leverhulme Trust for the award of a Research Fellowship. N.C. thanks the Scientific Council of the Paris Observatory for funding. S. Mathis acknowledge funding by the European Research Council through ERC grant SPIRE 647383

A new astrometric reduction of photographic plates using the DAMIAN digitizer: improving the dynamics of the Jovian system

International audienceThe astrometric monitoring of the natural planetary satellites is an important step to assess the formation and the evolution of these systems. However, in order to quantify relevant gravitational effects such as tidal forces, it is necessary to have very accurate observations over a long time interval. Unfortunately, the accuracy is decreasing as one considers older observations. To solve this issue, digitizing of old photographic plates is an attractive method, but a high accuracy in the measurement and the reduction of those plates is absolutely necessary.We have developed methods and algorithms adapted to specific plates provided by USNO, using the DAMIAN digitizer of ROB. From a set of 35 plates taken in 1974, we have been able to produce measurements with an accuracy better than 0.08 μm and after reduction using the UCAC2 catalogue, rms residuals of 35 mas (1.7 μm) for intersatellite positions (when the original reduction provided 100 mas) and of 65 mas for equatorial RA and Dec. positions (which were not possible to get with the original reduction). First results on the dynamics of the satellites and of the planet Jupiter are provided

ESPACE, European Satellite PArtnership for Computing Ephemerides

International audienceThe EC FP7 project entitled European Satellite PArtnership for Computing Ephemerides (ESPaCE) aims at strengthening the collaborative activities in the domain of the development of ephemerides and reference systems for natural satellites and spacecraft. An important part of the project addresses the extraction and analysis of astrometric data from observations by spacecraft not yet applied to dynamical solutions. They will be combined with ground-based astrometry in order to improve constraints on the dynamics and the physics of the objects. We will use all these data to provide improved ephemerides for natural satellites and spacecraft and to characterize the rotation properties of selected satellites. We also intend to investigate new technologies relevant to our aims, in particular Very Long Baseline Interferometry (VLBI) and Laser Ranging (LR) techniques. Another important part of the project will include merging (for the first time in Europe) the natural satellite astrometry data with spacecraft data in a global inversion. All the results and documents will be made available using standard formats (VO standard, SPICE kernels) for the use by space agencies and scientific community

ESPACE, European Satellite PArtnership for Computing Ephemerides

International audienceThe EC FP7 project entitled European Satellite PArtnership for Computing Ephemerides (ESPaCE) aims at strengthening the collaborative activities in the domain of the development of ephemerides and reference systems for natural satellites and spacecraft. An important part of the project addresses the extraction and analysis of astrometric data from observations by spacecraft not yet applied to dynamical solutions. They will be combined with ground-based astrometry in order to improve constraints on the dynamics and the physics of the objects. We will use all these data to provide improved ephemerides for natural satellites and spacecraft and to characterize the rotation properties of selected satellites. We also intend to investigate new technologies relevant to our aims, in particular Very Long Baseline Interferometry (VLBI) and Laser Ranging (LR) techniques. Another important part of the project will include merging (for the first time in Europe) the natural satellite astrometry data with spacecraft data in a global inversion. All the results and documents will be made available using standard formats (VO standard, SPICE kernels) for the use by space agencies and scientific community

A new consortium: the European Satellite Partnership for Computing Ephemerides (ESPaCE)

International audienc

A new consortium: the European Satellite Partnership for Computing Ephemerides (ESPaCE)

International audienc

A new consortium: the European Satellite Partnership for Computing Ephemerides (ESPaCE)

International audienc

ESPaCE: a new European project for Astrometry and Ephemeride activities

International audienc

ESPaCE: a new European project for Astrometry and Ephemeride activities

International audienc