Resolved spectra have been obtained from the ground of the O2(a1Δg) 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 &mgr;m and the (0,1) band at 1.58 &mgr;m are clearly separable from the hydroxyl airglow. The decay rate of the 02(a1Δg) during the twilight transition has been observed.