That's a fine image of the Rosette Mark, nice work.
55+ hours
I think that may be a record for one frame without combining several scopes or archived data on IIS, anyone gone longer? Not sure it was really necessary but if you can, heck, why not?
Personally I'm too not fussed on the diffraction spikes, they
look fake, I would suggest making them much thinner and more subtle
You must be wrapped with the new Observatory when you can do this sort of project
Mike