I captured this data on the night of excellent seeing on the 26th May. Ganymede and Io were in the same FOV of the DMK, but were a few Jupiter distances to the West.
I captured several runs. The first (top row) was captured with the extension tube (FL > 13,700mm) but the seeing was not yet at its best. The other runs were captured without the extension tube (FL > 10,300mm), and by now the seeing had improved.
Each run is shown in its native scale and with a 250% resized version. Also shown is a comparison to the Starry Night Pro view at the same time.
To me, the surface markings are unmistakeably real. In moments of great seeing (especially with Ganymede), the albedo features were even seen during raw capture. The features are also comparable to other captures of Ganymede over the past few months.
I believe the "egg" shape of Io is due to the darkened pole regions, and against "black" space, the camera isn't sensitive enough to pick it up - thereby giving the oval appearance. When Io transits across Jupiter, you can see these dark pole regions against the obviously bright Jupiter. The second attachment shows this from a capture of an Io transit on the 15th March.
The middle Ganymede and the last Io are excellent candidates to illustrate that real surface detail is being resolved here, and we are not simply seeing the effects of capture or introduced processing artefacts.
Terrific collage – well done! The Io-in-front-of-Jove image is stunning.
Detail on Ganymede and Io - 26th May 2007
