Comparisons of retrieved temperature and HCN profiles from a range of three different a priori modified HCN profiles for the case of the APEX data. Left: reference temperature shown in solid black, and retrieved temperatures in solid coloured lines. An associated temperature uncertainty at 15 K is shown by the shadowed area. Right: different lines show a priori HCN profiles (dashed) corresponding retrieved HCN profiles (solid) and their errors (shadowed area). The HCN profileof Marten et al. (2002) is shown in solid black.