That would explain the strange shape of the shadow on Mimas. At first I thought it was another moon but I couldn't think of any moons that would work.

okay, now I get it. We are basically looking down on the north pole of Mimas. The shadow of the A ring is covering the north polar region of Mimas but as you approach the equator, the sun appears below the A ring. As the sun approach Saturn (from Mimas' perspective), more of Mimas is covered in the shadow of the A ring.

That gap-filling image alongside the Ciclops Celestia rendering:

Now cleaned up and released, as if by magic: PIA10447.

OK, first post.
I have attached a rough map of Janus created by reprojecting some images on top of Tayfun Oners´ map. 180 deg longitude is in the center, the projection is equirectangular. It is far from precise because I had not all the pointing information for the images and used the shape model by Phil Stooke which is based only on Voyager data. At least features match up quite well in areas of overlap.
So my question is: Where does PIA 10447 fit? I can´t find any of the features in the other images.
Click to view attachment

A Mimas-Prometheus Kodak shot -- in the groove.

New Helene imae on the raw page.

Phil