Left: emission spectra of [C ii] (blue and black), [N ii] (red), and ¹³CO (green) for the ten lines of sight that are within b = ±0.̊25 are plotted as T_mb versus velocity. The central [C ii] pixel is plotted in blue and the average of the seven [C ii] pixels is plotted in black. The single and average [C ii] emission profiles are similar but not exactly identical owing to variations in emission across the footprint of the upGREAT array. The black vertical dashed line marks the tangent velocity of the Scutum spiral arm. Right: same as in the left panel for the eight lines of sight with b> 0.̊25. The downward black arrows mark a few of the clearly evident [C ii] absorption features.