spectra has been applied in the vicinity of each target feature; then, the two set of data have been re-sampled and averaged to obtain the final spectrum.

Analysis
========

The presence of amidogen radical in IRAS 16293-2422 has already been established by [@hily2010nitrogen], during the early phase of the CHESS key program. The results obtained in the previous study for the parent species have been used to test the validity of our data processing and the subsequent spectral analysis. Figure \[fig:nh2\] shows the strongest $J = \tfrac{3}{2} - \tfrac{1}{2}$ component of the fundamental $N_{Ka,\,Kc} = 1_{1,1} - 0_{0,0}$ transition of $o$- around 952GHz. Here, most of the HFS components are resolved and the intensity of the absorption lines is well above the $3\sigma$ noise level threshold.

![Spectrum of the $J = \tfrac{3}{2} - \tfrac{1}{2}$ component of the $N_{Ka,Kc} = 1_{1,1} - 0_{0,0}$ *o*- transition around 952GHz observed towards IRAS 16293-2422. The filled gray histograms show the observed spectra, while the blue trace is our HFS fit. The red sticks represent the position of the HFS components assuming LTE intensities.[]{data-label="fig:nh2"}](nh2_1-0_15-05.pdf){width="\hsize"}

The resulting model of the full HFS (plotted with the solid blue line in Fig. \[fig:nh2\]) has been computed using a 