D₂CO 4(0,4)−3(0,3) spectrum (black) with a velocity resolution of 0.16 km s⁻¹ extracted from the 4σ contour shown in Fig. 4 and smoothed three times with the Hanning algorithm overlaid with best fit (pink) obtained using single-component Gaussian fitting with FWHM, V_LSR and T_ex constrained using values obtained from fitting the HDCO transitions. The analysis was run twice, assuming upper limit values for the size of the emitting region of 0.3″ (covering source B emission) and 1.0″ (covering source A emission); the figure shown represents the latter. The rms level (0.15 K) is shown in green.