B-group identifications of the transitions of an OH band with the same rotational upper state (cf. Table 3). The tabulated wavelengths and zenithal mean fluxes of the lines of the OH(4–2) band are shown as example. Dashed and solid lines indicate transitions of the X²Π_1/2 and X²Π_3/2 state. The figure also indicates the R-, Q-, and P-branches that correspond to transitions with a change of the total angular momentum by −1, 0, and 1, respectively.