Modeled decomposition of some spectra around the first dense core. Each column corresponds to the spectra for one of the lines of sight listed in Table 2. Each row corresponds to a given line, from top to bottom: ¹²CO(1 − 0), ¹³CO(1 − 0) and (2 − 1), C¹⁸O(1 − 0) and (2 − 1), HCO⁺ (1 − 0), and H¹³CO⁺ (1 − 0). We show the decomposition of the full spectrum of ¹²CO (1 − 0) even though we only used its peak intensity during the fit. In each panel, the data and model spectra are shown as the black and green histograms, respectively. The contributions of the foreground, inner, background layers are shown as the plain lines in red, blue, pink, respectively, and the CMB layer is displayed as the dashed black line.