Comparison between the observed spectrum and the best-fit model for two spectra, spectrum 0002 (upper panels) in the inner core of NGC 3311 (R = 0.4 kpc), and spectrum 0073 (bottom panels) outside of the core (R = 8.2 kpc) in a region where the galactic halo dominates the light. For each spectrum, the larger top panels show the observed data (dark gray), the observed data with the improved sky subtraction (blue), the best-fit models (orange), and masked sky lines (light gray vertical bands). The bottom panels display the residual uncertainty of the fitting, with the percentual root mean squared errors (RMSE) indicated in the bottom left inset. Uncertainties (±1σ) in the spectra and models are indicated by the thickness of the lines. The stellar population results are indicated at the top of each plot.