H₂CO 3₂₂ → 2₂₁/3₀₃ → 2₀₂ (top) and 3₂₁ → 2₂₀/3₀₃ → 2₀₂ (bottom) integrated intensity ratio map. Ratios are calculated when the H₂CO 3₀₃ → 2₀₂ line emission is detected above 5σ. The top and bottom rows should be nearly identical, and the difference mainly comes from the CH₃OH contamination in H₂CO 3₂₂ → 2₂₁. The wedges at the sides show the line ratios. The beam size of 30″ is shown at the bottom-left corner. Sgr A^∗ is the origin for the offset coordinates and shown as a cross.