Example of this work’s stellar population fitting process. The top panel shows our best-fit model spectrum (blue) and SED (green) compared to the stacked spectrum (pink) and SED (orange), while the bottom panel zooms into the optical range. Residuals are shown for the SED in the top panel and for the spectrum in the bottom panel. The spectral regions around the emission lines are masked during the fitting, as indicated by the shaded regions in the bottom panel.