Rotational NH₃ temperatures determined for the protostars W51e2-E and W51e2-NW, and cores W51e2 and W51e8 (from left to right, and from top to bottom). The temperatures are fit to the slope of the normalized NH₃ column density N_u (in units of cm^-3) plotted against the energy of each transition E_u (in units of Kelvins) using Eq. (A.8). The blue line is a fit to the measured columns without opacity correction. The magenta line is the fit after applying the opacity corrections, using the optical depth values in Table 3. We excluded the (10, 10) transition from the fit because of much higher rms.