Densification of reference frames: towards new VLBI observationaml strategies
Laurent Chemin & Patrick Charlot
(Laboratoire d'Astrophysique de Bordeaux)
The goal of this project is to define new Very Large Baseline Interferometry strategies for astrometric surveys in order to densify the reference grid defined by observations of extragalactic sources. This could be achieved by combining the observations of faint radio sources by the phase referencing technique with those of bright sources observed by group delay.
The evection resonance : solar and oblateness perturbations
Vienne A., Frouard J., Fouchard M.
(IMCCE / Université de Lille)
Among resonances commonly influential to the dynamics of satellites, the evection resonance introduces an important correction to the precession frequency of the satellite, as it is well known for the Moon's problem. However, the dynamic of the resonance itself, which is important for satellites stability and capture topics, including its libration and circulation regions, and its elliptic and hyperbolic points, has not been extensively studied. Here we investigate its dynamic with an improved analytic model, making comparisons with previous works, and resort to numerical methods and integrations to study and localize the different features of the resonance. This resonance is found in the outer orbital region near the orbital stability limit. However we also study and localize an other libration region that can be found much more closer to the parent planet when its oblateness is taken into account in the model.