Column densities (top) and temperatures (bottom) of molecules in the central region. The error-bars represent 3σ uncertainties derived by the χ² minimization procedure. The errors are largely underestimated. The column densities represent the main isotopologues of the species. A correction of about 20% and 30% is necessary for O- and C-bearing molecules to account for the presence of ¹⁷O and ¹³C, respectively. The vertical dashed line shows the median temperature of 17.1 K. For molecules labeled with an asterisk, LTE results instead of non-LTE are presented.