Diagnostic plots, re-plotted with vertical lines:

here is the zoomed plots after subtracting the FeII template and continuum. the dotted-red vertical lines are the approximate boundaries we use to calculate the sigma. of course I didn't recorded the information about these boundaries. I kept it for CIV technique but not the MgII. This approximately based on what I assumed in measurements.

============ Notation:

panel top-left: cyan is the raw-spectrum, black is the reconstructed spectrum. both pseudo-continuum subtracted

panel top-right: black is the spectrum after PCA, red is the FeII+continuum, green is the continuum.

panel top (the big one): spectrum after PCA

panel low-right: same as top-right panel but before PCA

panel low (the big one): spectrum before PCA

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vari=0.79, MBH_ab=1.01E9

vari=0.72, MBH_ab=1.47E9

for this case, if the line doesn't cross the zero we eventually stop when the profile is approximately horizontal in average.

vari=0.72, MBH_ab=1.7E9

===========

this is the case when after and before PCA gives very close masses.

vari=0.06, MBH_ab=9.21E8