Maps of the HCN/HCO⁺, H¹³CN/H¹³CO⁺, and HCN/HNC J = 4−3 integrated intensity () ratios across W49A (greyscale and contours). Contours show 10 to 100% of the peak values (in steps of 15%) which are 1.4 for HCN/HCO⁺, 4.9 for H¹³CN/H¹³CO⁺, and 10.3 for HCN/HNC. A cutoff integrated intensity was applied to each transition before calculating the ratio to avoid divide-by-zero errors in low signal regions of the maps. The cutoff values are 1.5 K km s^-1 for HCN, 0.5 K km s^-1 for HNC, 3.0 K km s^-1 for HCO⁺, 0.7 K km s^-1 for H¹³CN, and 0.3 K km s^-1 for H¹³CO⁺.