CO and isotopologues in the direction of AFGL 2298. The species and their corresponding rotational lines are indicated in the upper-left corner of each spectrum. All spectra are displayed at the same velocity range. To ease a comparison, the J = 1 → 0 (left column) and the 2 → 1 (right column) lines are plotted on the same intensity scale. The most intense components, roughly at 38 and 46 km s⁻¹ (components A and B, see text) are the only ones present in all the lines. The C¹⁷O lines have hyperfine structure, which is noted in the splitting at component B.