Integrated intensity of the H₂CO 3₀₃–2₀₂ line (left) and H₂CO 3₂₂–2₂₁ line (right). Contours every 2 K km s^-1 (~3σ). Both lines are integrated between 0 and 9 km s^-1. Greyscale background of both figures is SCUBA 850 μm continuum. Refer to Fig. 1 for a guide to the symbols used for the compact objects.