IUE observations of comets P/Brorsen-Metcalf and Okazaki-Levy-Rudenko

Comet P/Brorsen-Metcalf (1989c) was observed with the International Ultraviolet Explorer (IUE) on several dates from 27 July 1989 through 5 August 1989; comet Okazaki-Levy-Rudenko (1989r) was observed in low dispersion with IUE on 2 and 22 December 1989. The water production rates for P/Brorsen-Metcalf were derived from OH measurements using the vectorial model of Festou (1981). Included also are the water production rates for Okazaki-Levy-Rudenko. Two estimates of the water production rate from the O I emission around 1304 A(octogons) are included. The ultraviolet continuum was not reliably measurable in comet P/Brorsen-Metcalf in most of the spectra, but Afp is approximately 30 cm for 2 August. For the comet Okazaki-Levy-Rudenko, an Afp = 50 cm was derived for 22 December. Both comets have very little dust compared to other recently observed comets. The ratio of CS to water production rates are presented. Relative to water, both comets had less CS than P/Halley in the same range of heliocentric distances. The CS production rates were obtained from a Haser model, assuming a short-lived parent (CS2). Because the dynamic range of the IUE spectrographs are limited, not all species can be measured in each spectrum. The P/Brorsen-Metcalf spectra from 31 July and 3 August were obtained from the NSSDC Archives. Due to the observing technique used for these spectra, the exposure time and hence, the brightnesses and derived quantities have a small uncertainty associated with them.