Three minor Saturnian moons

[granthutchison]

Phil Stooke provides shape models and texture maps for the three Saturnian moons Prometheus, Epimetheus and Janus. I've generated and texture-mapped three 3ds meshes, and praesepe has smoothed the result.
They're available for download at
http://www.lns.cornell.edu/~seb/celestia/hutchison/#5
I've also provided the necessary RotationOffsets to bring the moons into correct alignment with Saturn, given the (imaginary!) MeanAnomaly values assigned to them in minormoons.ssc.
(Given the chaotic behaviour of all these inner moons, it seems pointless to try to assign them any real elliptical elements.)

Grant

[HankR]

Grant,

I presume that osculating elements at specific epochs are available via Horizons. Do you have a guess as to how frequently these would need to be updated to obtain reasonably accurate positions?

- Hank

[granthutchison]

For all three satellites the ascending nodes and pericentres are precessing pretty rapidly, twisting right around Saturn in just a few months. But given the low eccentricities and inclinations involved, that's not going to make a glaringly obvious difference to the location of the satellite in Celestia. The big problem is going to be cumulative errors in mean anomaly because of mutual perturbations. Janus and Epimetheus have a close encounter and more or less exchange orbits every 4 years. Prometheus passes Pandora, its main disturbing influence, every 24 days, and its gravitational interaction with the F-ring particles changes all the time as their orbits precess relative to each other.
So we're talking significant changes over only a few years.

Grant