First row: total integrated intensity (K km s^-1) of ¹²CO, velocity and line width at FWHM (km s^-1) obtained from the Gaussian fit of the ¹²CO line. Second and third rows: total column densities and best-fit values for velocity and line width obtained from the Gaussian fit of the ¹³CO and C¹⁸O lines, respectively. The column densities are derived with a constant excitation temperature of 15 K. The contour in the W(¹²CO) map shows the observed ¹²CO emission in the range of [−4,−1 ] km s^-1 which was not included in our analysis. The lowest contour is at 0.7 K km s^-1 and the contours increase with 0.7 K km s^-1 steps. The contours in the ¹³CO and C¹⁸O column density maps correspond to 45%, 60%, 75%, and 90% of the maximum value of τ₂₅₀. We have masked regions with S/N < 3 in the velocity and line width maps of ¹³CO and C¹⁸O.