Same as Fig. 1 but for the J = 2₀₂ − 1₀₁ transition of HNCO (isocyanic acid) and its isotopologues HN¹³CO, H¹⁵NCO, and DCNO (upper and second raw panels). The upper panel also shows a zoom to the data to exhibit the hyperfine lines of HN¹³CO. The scale of the zoom is indicated in blue on the right-Y axis. The third row shows the J = 2 − 1 line of HCNO (the J = 4 − 3 is shown in Fig. A.2) and the J = 2₀₂ − 1₀₁ line of HOCN (cyanic acid). Finally, the bottom panels show two hyperfine components of the J = 7/2 − 5/2 line of NCO in its ²Π_3/2 ground state. The lambda-type doubling components, e and f, are indicated. The derived line parameters are given in Table A.2. The hyperfine structure was considered in the modelling of the lines (shown by the red lines).