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 O, CS, NH, and various minor species, set
upper limits to undetected emissions features, and calculate
the Af 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.