Uniform Analysis of IUE Spectra of Comets

S. A. Budzien (Naval Research Laboratory), D. G. Schleicher (Lowell Observatory), K. F. Dymond (Naval Research Laboratory)

The International Ultraviolet Explorer (IUE) satellite has provided a large database of cometary spectra over a period of 18 years. During the IUE lifetime varying solar activity levels, instrumental degradation, data processing revisions, evolving coma models, and our growing understanding of comets have rendered previous IUE cometary surveys incomplete or difficult to compare. The IUE spacecraft was retired in 1996. We have performed a uniform reduction of over 400 mid-ultraviolet (2000-3000 Å) cometary spectra in the final archive (NEWSIPS) data format. We use automated data reduction techniques developed for handling large volumes of UV airglow data expected from upcoming NRL satellite experiments. We derive gas production rates for H tex2html_wrap_inline12 O, CS, NH, and various minor species, set upper limits to undetected emissions features, and calculate the Af tex2html_wrap_inline14 parameter for dust-scattered solar radiation. Solar activity and sensitivity degradation effects have been taken into account. The production rates, abundance ratios, dust parameters, and cometary orbital data are analyzed and discussed with respect to chemical evolution of comae, compositional classes of comets, and the results of ground-based photometric surveys.