High‐resolution dayglow O I (1304 Å) and O I (989 Å) rocket observations

Abstract

High‐resolution (∼1 Å) dayglow observations of the O I(1304 Å) and O I(989 Å) multiplets were made from an Astrobee‐F rocket payload (25.046 CE) launched from White Sands, New Mexico at local noon on June 27, 1980 to an apogee of 260 km. Three components of the O I(1304 Å) multiplet were measured at zenith angles of approximately 50° and 140° at 1.1 Å resolution. Over the entire altitude range of observation, i.e., 100–260 km, the three components were found to be equal to within ±15%. The absolute intensity profile of the total O I(1304 Å) multiplet was approximately 30% greater than that obtained on an earlier rocket flight (25.029 GA) launched January 9, 1978 from White Sands, when the solar activity and the elevation angle of the sun were both lower. The shape of the O I(989 Å) multiplet distribution observed on the flight at 1.3‐Å resolution was indistinguishable from an optically thin source with the energy levels of the excited state populated according to their statistical weights in spite of the large optical depths of the O I(989 Å) multiplet at rocket altitudes. Experiments with a laboratory UV source also showed the insensitivity of the multiplet distribution to the optical depth of the source. These results are entirely consistent with a recently developed PFR radiative transport code (Meier, this issue) in the absence of selective absorption by rotational lines of N2.