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Recent Results on the Dynamics of Atlas

Recent Results on the Dynamics of Atlas. Nick Cooper, Stefan Renner Carl Murray. Encelade Meeting, UPMC, 22 January 2014. Charnoz et al. (2010). Astrometric Data. 2580 Cassini ISS observations of Atlas, Prometheus, Pandora, Janus, Epimetheus QM SATELLORB and F Ring Images

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Recent Results on the Dynamics of Atlas

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  1. Recent Results on the Dynamics of Atlas Nick Cooper, Stefan Renner Carl Murray Encelade Meeting, UPMC, 22 January 2014

  2. Charnoz et al. (2010)

  3. Astrometric Data • 2580 Cassini ISS observations of Atlas, Prometheus, Pandora, Janus, Epimetheus • QM SATELLORB and F Ring Images • Data span Feb 2004 to Aug 2013 • Atlas observations mostly centroided • UCAC2 for pointing correction • Phase correction • SATELLORB astrometry by Mike Evans

  4. Numerical Model • Integration of full equations of motion in 3D • Perturbations from 8 major satellites, Sun, Jupiter • Saturn’s oblateness up to J6 • Runge-Kutta-Nystrom 12th order integrator • Variational equations integrated simultaneously, iteratively fitting to observations • Solving for states and masses of Atlas, Prometheus, Pandora, Janus and Epimetheus at epoch

  5. O-C Residuals Pre-fit (SAT353) Post-fit

  6. O-C Post-fit Residuals

  7. Mean longitudes vs. time Resonant arguments vs. time ILR CER

  8. Atlas Geometrical Elements Atlas, Prometheus, Saturn only Full Numerical Model

  9. FLI vs time 3-body Numerical Model (Atlas, Prometheus, Saturn) Full Numerical Model

  10. Coralin Surfaces of Section (Starting Conditions from Numerical Fit) ATLAS a_mean=137665.39 km

  11. Coralin Surfaces of Section (Starting Conditions from 3-body Model) ATLAS a_mean=137665.39 km

  12. Summary • Fit to new astrometry: significant reduction in O-C residuals. • Order of Magnitude improvement in mass estimates. • Atlas dynamics dominated 54:53 resonance with Prometheus. • Another example of coupled ILR/CER motion! • Regular and chaotic episodes (FLI analysis). • Chaos is due to Prometheus only. • Atlas, Prometheus dynamics can be modelled as a 3-body system (CORALIN).

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