Comparison of the observed spectra (black) with the uv-fitted spectra of the Gaussian fit (gray) and the fit including a Gaussian plus a delta function (red). The observed spectra were extracted from the images with an aperture of 5″ diameter. The effective beam size in the observed images is 0.55″ × 0.48″. We note that the y-axis scales differently for the first spectral line, which is the strongest. The respective scales are given on the left-hand side for the first line, and on the right-hand side for the remaining lines.