OH prompt emission in Comet IRAS-Araki-Alcock (1983 VII)

Following Bertaux's (1986) suggestion that photodissociative OH fluorescence can furnish a direct measure of water-density distribution within about 100 km of the cometary nucleus, if sufficiently high spatial resolution is available, attention is presently given to IUE-obtained UV spectra of two comets which differ only as to effective spatial resolution, in order to search for OH prompt emission. IRAS-Araki-Alcock (1983 VII) and Tuttle (1980 XIII) spectra are compared at comparable heliocentric, but differing geocentric, distances; evidence is thereby obtained for OH prompt emission in Comet IRAS-Araki-Alcock, whose implied water-production rate reflects an instantaneous value which may be compared with that derived from OH solar resonance fluorescence.