Excitation map (top panel) for the [C I] line ratio observed at offset position (−130′′,−10′′) in the velocity channel 19–20 km s^-1. The contours and labels correspond to the column density per line width N/ ΔV (cm^-2 km^-1 s, in log₁₀ scale). In the middle panel the contours and labels correspond to the excitation temperature T_ex (K) of the J = 1 → 0 (left) and J = 2 → 1 (right) transitions, while the bottom panel shows the corresponding optical depths for each line.