Same NH₃ data from GBT + VEGAS spectrometer as in Fig. 9. The top window shows the first frequency-shifted spectrum with the right-hand side smoothed by a median of 0.4 MHz in width. The middle window shows the second frequency-shifted spectrum smoothed on the left-hand side. The bottom window shows a comparison between the original folded spectrum and the half-smoothed folded spectrum. The baseline is computed between the two vertical dashed lines as in Fig. 9.