Radiative transfer model maps (see Sect. 4.1) of o-H₂CO 5_1,5–4_1,4 (left) and H¹³CN 4–3 (right) with freeze-out effects ignored. These maps are counterparts of the more physically correct ones where freeze-out is implemented, in the middle right and bottom right panels of Fig. 6. Color scales and contours are identical to those used in Fig. 6, with the exception that negative intensity contours (dashed) are included in this figure.