Moment 0 map of HDCO 4(1,4)−3(1,3) integrated between -5 and 8 km s⁻¹. This velocity range was chosen to include the two unblended HDCO emission components shown in Fig. 6. Contours start at 4σ and end at 16σ in 4σ increments (σ = 8.5 mJy beam⁻¹ km s⁻¹). The pink contour illustrates the area within which the spectrum in Fig. 6 was extracted, defined as the 4σ contour shown in Fig. 4. The locations of protostars A and B are shown by the black stars. The ALMA synthesised beam is shown in the lower left corner.