Overview of the two methods used to determine the column density of D₂O toward L483. Left: Synthetic spectrum model for the emission feature toward L483 for an assumed source size of 0.′′ 2. All molecules are fitted with double Gaussians. The estimated optical depth τ for both D₂O profiles are shown in the upper left corner. The synthetic spectrum includes components from D₂O, CH₃OD, and CH₃OCH₃. Right: Least-squares fit to the emission profile. The best fit includes three components, one identified as D₂O, one identified as CH₃OD at 316.7651 GHz, and a third component that may be either CH₃OD at 316.7916 GHz or CH₃OCH₃ at 316.7904 GHz, or a convolution of both.