Maps of column densities and abundance ratios toward IRS 63. Upper panels: Column density maps of H₂CO, HDCO, and D₂CO derived assuming LTE and optically thin emission at the temperature derived from the HDCO lines (T_ex = 45 K). Lower panels: Maps of the abundance ratios [D₂CO]/[HDCO], [HDCO]/[H₂CO], and [D₂CO]/[H₂CO]. The continuum emission at 1.3 mm is in black (contours from 10σ with steps of 500σ, with σ = 0.7 mJy beam⁻¹).