Contours of constant ﹩\chi ^{2}_{\nu }﹩ value (the goodness‐of‐fit) over the parameter space spanned by the beam‐filling factor (η_bf) and column density (N) (left panel), and by the rotation temperature and column density (right panel). A cross marks the best‐fit parameters (giving the smallest ﹩\chi ^{2}_{\nu }﹩) in each of the panels. In the left panel the rotation temperature is not a free parameter, but is fixed at 182 K, and because of this the confidence regions are only approximate.