In this paper we analyze daylight 1.58-&mgr;m limb radiance profiles obtained by the Spectral Infrared Rocket Experiment (SPIRE) in the 40- to 70-km tangent height region, near the dawn terminator. Photochemical model calculations indicate that the O2(a1Δg, &ngr;=0)→ O2(X3&Sgr;g-, &ngr;=1) transition provides the necessary radiance if we choose the Einstein coefficient for the (0,1) transition, A(0,1)=5.0¿10-6 s-1. This value is within the range of past field and laboratory measurements but 3 times larger than what the Franck-Condon principle would predict assuming the accepted value of 2.58¿104s-1 for A(0,0). One-dimensional inversions of the radiance give reasonable profiles of O2(1Δg) for altitudes above the radiance peak. Using the best fit values for A(0,1), a two-dimensional model treatment can give good agreement to the limb radiance even below the radiance peak, but there is not enough information in the limb radiance scans to do a two-dimensional inversion. The two-dimensional simulation of the limb radiance is more successful since it takes into account the change in the O2 singlet delta density with solar zenith angle and not just just altitude, and because the direct calculation avoids the numerical error that accumulates in the one-dimensional inversion especially below the radiance peak.