Left: integrated intensity map of the C¹⁸O J = 3 → 2 line as observed with the JCMT. Crosses mark the observed positions and the star indicates the position of FIRS 2 (RA (J2000) = 21^h43^m017 Dec(J2000) = 66°03′23′′). The grey scale varies linearly between 1 K km s^-1 and 5.5 K km s^-1, and the thin black contours correspond to 1.5, 3.0, 4.0, and 5.0 K km s^-1. The JCMT beam is shown in the bottom-left corner. The red and blue contours are adapted from Fig. 1d of Fuente et al. (2001) and trace the high velocity CO J = 2 → 1 emission, the contours start at 10 K km s^-1 and increase in steps of 5 K km s^-1. Right: spectra of the C¹⁸O J = 1 → 0, J = 3 → 2, J = 5 → 4 and J = 9 → 8 lines towards FIRS 2.