Ultraviolet spectroscopy of comets

The UV spectra of a comet, Comet Seargent 1978m, were obtained two weeks after the comet's discovery before any ground-based spectroscopic observations were made. The second comet observed with IUE was Comet Bradfield 1979e. It was first observed on January 10 and 11, 1980, and subsequently on several occasions until the beginning of March of 1980. The comets were observed at various heliocentric distances in the low and high dispersion mode. In the long wavelength region, emission bands of OH, CS, CO2(+), NH and CO(+) were identified, and the rotational structures of the (0, 0) and (1, 0) bands of OH were resolved. In the short wavelength region, emission lines of H(L alpha), O I, C I, C II, and C 1 and the CO fourth positive bands appeared. The results of these observations are the detection of S I; indications that CS exists as "Parent Molecules" in the cometary ice; the resolution of the (0, 0) and (1, 0) bands of OH; the determination of the spatial variations of various emissions; the determination of the variation of the production rates of various species, especially of H and OH, with heliocentric distance.