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Cassini UVIS Team Meeting

Cassini UVIS Team Meeting. January 2009. Josh Colwell Slides. Cube Generator. Reads raw FUV and EUV data files. Applies flatfield and calibration. Calls Geometer for all pixels in data files. Writes an image cube with geometry backplanes.

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Cassini UVIS Team Meeting

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  1. Cassini UVIS Team Meeting • January 2009 Josh Colwell Slides

  2. Cube Generator • Reads raw FUV and EUV data files. • Applies flatfield and calibration. • Calls Geometer for all pixels in data files. • Writes an image cube with geometry backplanes. • I'll now take lead responsibility on CG maintenance and upgrades. • I need input on user needs and priorities.

  3. Current CG Backplanes • Pixel RA/Dec, Lat/Lon (center and corners) • Pixel incidence, emission, phase angle (center only) • Pixel occultation lat/lon, rayheight, line-of-sight distance (center only) • Sub-S/C lat/lon, S/C altitude, Sub-solar lat/lon • Target body RA/Dec, phase, emission, incidence angles • S/C state vector wrt target • Time, list of kernels • Ring geometry information

  4. Possible CG Mods • User Interface. • Code cleanup (necessary, but should be essentially invisible to user). • Tighter interaction with Geometer. • Current version on team website is buggy. I have another version direct from KL that I modified that is working. What versions are people using? • Additional geometry needed? • Format of cube (has changed once, still not ideal)? • License-free version? • Any other requests?

  5. Current CG GUI

  6. Data Cube Image Shown in Geometer

  7. Image Cube Animation in Geometer

  8. HSP Performance Does not include "Impact" data sets (~108 counts)

  9. HSP Performance

  10. CEM Ring Observations • 20 ring stellar occs completed in CEM to date. • Anticipating about 20-25 more through end of CEM. • Spectral observations continue to be made in rider mode only. Low solar incidence angle is limiting factor at this season.

  11. CEM Ring Occs To Date

  12. Cassini Division

  13. Atlas 5:4 Density Wave 13

  14. Atlas 5:4 Dispersion

  15. Density Wave on a Ringlet

  16. Opacity in Cassini Division

  17. Opacity in CD and A Ring

  18. Cassini Division Density Wave Results • Viscosity gives ring thickness of 3-6 m. • Local surface mass densities: 1-5 g/cm2 in Cassini Division, 20-50 g/cm2 in A ring. • Largest CD particles ~3-5 times smaller than largest A ring particles. • CD "ramp" particles more like A ring than Cassini Division.

  19. C Ring Waves

  20. C Ring Wave Examples New waves Rosen "j"

  21. Rosen "j" Wave

  22. Resolving the Edge Signal (Ι) I=I0e-τnL/H to star Ring Radius I=I0e-τn Point of first attenuation H B L=H/sin(B)-dr/cos(B) dr Ring Edge

  23. Ring Edge Models • Applied edge-fitting to Huygens ringlet and Titan ringlet inner edges. • Knife-edge profile inconsistent with some occultations at high incidence angle. • Logistic function (S-shaped) radial profile with uniform vertical profile: • No single set of parameters provides a good fit to all occultations. • Next need to separate azimuthal structure from radial and vertical structure.

  24. Huygens Ringlet Inner Edge

  25. Titan Ringlet Inner Edge (1)

  26. Titan Ringlet Inner Edge (2)

  27. Goodness-of-Fit for Edge Model

  28. Goodness-of-Fit for Edge Model

  29. "Sigmoid" Model Fails to Fit all Occs

  30. C Ring Autocorrelation

  31. CD/A Ring Transition

  32. Current Work • Map edge profiles in ring longitude • Huygens ringlet structure • Simulate moonlet perturbations on edges • C ring wave analysis • C ring excess variance - ballistic transport modeling (with Estrada, Cuzzi) • Outer Huygens ringlet ("strange ringlet") modeling (with ISS) • A ring edge modeling (with ISS)

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