  HfS is a tool to fit the hyperfine structure of spectral lines, with multiple
velocity components. The HfS_nh3 procedures included in HfS fit simultaneously
the hyperfine structure of the NH$_3$ (J,K)= (1,1) and (2,2) transitions, and
perform a standard analysis to derive $T_\mathrm{ex}$, NH$_3$ column density,
$T_\mathrm{rot}$, and $T_\mathrm{k}$. HfS uses a Monte Carlo approach for
fitting the line parameters. Especial attention is paid to the derivation of
the parameter uncertainties. HfS includes procedures that make use of parallel
computing for fitting spectra from a data cube.
