Of course it may not actually be the Enke gap I've been seeing Norme. As David mentioned in one of his posts above, there's a high chance it could be simply a contrast feature at the outer edge of the A ring. All I'm sure of is that I have seen the feature so many times in my various refractors over the years, that I'm confident something is going on at that point on the ring.
In my observations, often the outer edge of Cassini's division seems softer than the edge against the B ring, but again that too may be down to contrast. Radial streaks in the A ring and radial spokes in the B ring can be seen quite regularly too. I've often noticed a bright polar spot and wonder if that may be due to aurora? Who knows?? I just draw what I see!
I have sometimes wonder about not drawing what you see. What I mean is, we sometimes see illusions and some form of mental or optical affects that are not real...apparently. But, we see them none the less. One that comes to mind is the greenish contrast hues on Mars. I know these are illusion, so I do not sketch them as green features. But, I also know I am fooled sometimes, just not often when or what affect is fooling me. I do not have a library of illusions in my mind to cross check my observations. So, I agree, sketch what we see, regardless, and maybe it'll get sorted in the wash.
As for the A ring and Enke division, yea I have gotten some hints that something is going on, too. Tantalizing hints of Enke. But I am always talked out of it, as David says, some quick jitters in the seeing which I have seen happen with star images. Or something, some small vague contrast effect possibly the interplay of light and dark involving Enke. Anything other than the Enke division in a modest aperture of modest quality. But, who knows for sure. I know the rapid image shift is some seeing conditions, even excellent seeing, is real and the effect can be similar to a lucky snapshot of Enke. So, for me, the sighting remains tantalizingly close but no cigar. I wish I could say I've seen it, but my argument is not strong enough to argue back with any credibility.
I have yet to see the spokes or any radial streaks. Normally those are reserved for larger apertures with better contrast on those scales. However, I am sure the spokes are present in the image as a low contrast detail that might be eked out by keen observer and a high contrast afocal image. That's certainly possible. Aurora, yikes! If any scope (observer) can do any of it, certainly a large quality refractor can with a keen observer at the controls. Together, this offers the best chance of seeing detail at the margin. Even a modest obstruction, some aberration, or weak coatings, etc., can push detail at the margin beyond the margin to be picked up, again, by a larger aperture by an intrepid observer.
Again, these details are certainly large enough to be "resolved" in a modest aperture and are present in the image, it's just a matter of object and image contrast and personal acuity...and seeing, and high contrast optics, and whatever. Nice segue back to the belts on Saturn, because this holds true for them, as well.
It's all fun, pushing ourselves to the limit of our perception of the telescopic image and returning safely home totally sane and not corrupted by the dark side. Sometimes we see some strange things in the hinterlands at the limits of our perception. Sometimes they are real, sometimes illusion, and sometimes imagination. But, we see them and sketch them, regardless, without knowing but believing they are real. It's a hazard to our hobby we have to endure as observers. The beauty is, we can actually learn to trust ourselves out beyond the horizon of our day to day reality and come back with a real story to tell of rings, and gaps, and of belts. That's observing.
Edited by Asbytec, 22 May 2019 - 07:57 PM.