cropping grid for masked fit; changed output to a single pdf
remove all 3 FeH bands
add additional uncertainty; median of diff btwn model and data

at the suggestion of Jason Wright, I'm trying to add additional
uncertainty to the data (or to the fit, really) that accounts for
the fact that the models can only get so close to the data
(because the models are definitely missing physis and we know this)

Right now I'm interpolating/normalizing the models as usual, then
taking the median of the difference between the model and data and
adding that in quadrature to the existing uncertainties in the
data