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A spectral search for Lyman‐Birge‐Hopfield band nightglow from Spacelab 1

1985; American Geophysical Union; Volume: 90; Issue: A5 Linguagem: Inglês

10.1029/ja090ia05p04427

2156-2202

Marsha R. Torr, D. G. Torr, Jong Won Eun,

Ionosphere and magnetosphere dynamics

The Lyman‐Birge‐Hopfield (LBH) system of N 2 requires 8.5 eV for its excitation. Measurements were reported several years ago of significant intensities (≲1 kR) of this system at mid‐latitudes at night. It thus becomes important to establish whether such LBH nightglow is generally present in the nightglow in order to identify the source mechanism. In this paper we examine the ultraviolet spectra gathered at night from Spacelab 1 for further information on this phenomenon. We find that emission with the LBH spectral characteristics reported earlier are present in each of the five data sets analyzed. Each spectrum indicates an emission system arising from a vibrational distribution peaking at υ′ = 0, and the band ratios are convolved with O 2 absorption. The intensities for the entire band range from 500 R to 5 kR in slant path intensity. The spectra studied include one obtained at northern mid‐latitudes (winter), one at equatorial latitudes, and three in southern mid‐latitudes (summer). In addition to these data obtained with the instrument field of view in fixed configurations with respect to the earth, we have also examined three limb scan sequences for information on the altitude distribution of the emission.