χ² plot for C₂H₅CN for B1-c in the Band 5 and 6 data. The dots in the background show the grid used for this molecule, and the contours show the 3σ, 2σ, and σ levels of the best fit. It is seen that T_ex is constrained to between ~200 K and ~ 400 K, whereas the column density is well determined at (5.8 ± 1.7) × 10¹⁴. We note that the vibrational correction factor is not taken into account for this plot.