Top: average raw response (extinction-corrected observation)/(radial-velocity shifted model), divided by the smoothed response for L97-3, for EG 274. The narrow spikes are due to mismatches in the line cores, while the broad bumps at 405 nm and 420 nm are due to imperfect line broadening, which underestimates the flux between the lines in the model spectra. Middle: raw response from the top plot, with large scale variations removed by a low-order polynomial fit and smoothed (black). The black curve was fit with a spline (red) after masking the regions of the line cores (masked regions in cyan). Bottom: model spectrum before correction (black) and corrected with the fit (red).