Maps of the average brightness temperature of the ¹³CO(J = 1−0) line in four contiguous velocity ranges. The main-beam temperature scale is indicated by the color bar on the right. The contour shows the value of 8.9 K  km s^-1 in the W₀ map, corresponding to 0.43 K in the mean temperature map integrated over the −0.5−20.5 km s^-1 velocity range. The set of coordinates used for the observational campaign takes the Horsehead PDR as a reference point, and aligns the IC 434 PDR along the vertical axis (14° counter-clockwise rotation with respect to equatorial coordinates). The numbered squares in the first panel show the positions of the spectra presented in Fig. 3, from left to right.