We suspect this really might be (warts and all) the world's deepest plausibly amateur Helix in H-alpha.
Full sized image here (2.2MB)
A three-panel (highly overlapping) mosaic, with at least 24 hours exposure, 2x2 binned, at each pixel, with a 20" PlaneWave CDK. Most of the image has 72 hours of exposure.
We've roughly doubled the exposure since last time. The Western chevrons are much less noisy now, and much sharper. We've added a sliver of extra real estate at the far right, where there is now a new, somewhat wriggly radial smudge heading off toward four o'clock.
The faintest details that are clearly and unambiguously recognizable in this radial smudge (where the exposure is 24 hours), are about 16 ADU above their immediate environment, which translates to 24 photo-electrons (48 photons) per one hour sub. There are other more ambiguous features surrounding it, which are visible in the Galex image.
The bright centre is overlain with 4 hrs of unbinned H-alpha. The blending of the two images has produced some artificially darker regions at the interface, but this does not affect the faint outer details.
We think we'll put our pen down now.
Very best,
Mike and Trish