Twilight transition spectra of atmospheric O₂ Ir emissions

Resolved spectra have been obtained from the ground of the O 2 (a¹Δ g ) emissions from the upper atmosphere utilizing a wide‐field interferometer with a cryogenically cooled germanium detector. The rotational structure of both the (0, 0) band at 1.27 µm and the (0, 1) band at 1.58 µm are clearly separable from the hydroxyl airglow. The decay rate of the O 2 (a¹Δ g ) during the twilight transition has been observed.