Interstellar [CII] and [OI] lines have been observed by the Balloon-Borne Infrared Telescope (BIRT) in corporation with a Fabry-Perot spectrometer. Two balloon flights were successfully made from Palestine, Texas in May/June 1988. With a new method of "frequency switching", diffuse [CII] line emission was efficiently detected and mapped in extended regions around HII/molecular cloud complexes and in a wide area of the Galactic plane. It has been shown that the [CII] emission is very strong and ubiquitously distributed in interstellar space in the Galaxy. © 1992.
Shibai, H., Okuda, H., Nakagawa, T., Maihara, T., Mizutani, K., Matsuhara, H., … Nishimura, T. (1993). Balloon observations of interstellar [CII](158 micron) and [OI](63 micron) lines. Advances in Space Research, 13(2), 201–204. https://doi.org/10.1016/0273-1177(93)90300-Z