Just to check - the final noise being added to the for the simulated image is still COSMOS-like correlated noise, right?  I know there was discussion changing this (my suggestion on #430 , here: https://github.com/GalSim-developers/GalSim/issues/430#issuecomment-22253575 ) of  to being just a simpler final noise model (e.g. Poisson or Gaussian) to make this all a bit less confusing to the end user... Do you still agree with that?  If so, I'm happy to make the changes myself (including to the documentation)