We examine long-term low-dispersion IUE, SWP and LWP spectroscopy of the R
Coronae Borealis (RCB) star V854 Cen, obtained across the deep 1991, 1992-1993
and 1994 declines. We also report the optical light curve for the star in the
interval 1987-1998, including multi-color photometry obtained during 1989-1998.
Analysis of the UV emission line spectra indicates most lines decay during
the deep declines on characteristic timescales comparable to that reported for
optical features. Fe, Mg and neutral C lines decay on timescales of typically
50-100 d. Other lines, notably ionized C lines, decay on longer timescales (>
200 d) or appear to be unaffected by the declines. The general nature of the UV
emission lines and other UV features during the declines is consistent with the
E1/E2/BL line-region model developed from the behavior of optical spectral
features during declines. However, the detailed line-behavior indicates large
intrinsic variability between decline events inconsistent with the simple
E1/E2/BL model. Limited temporal coverage prevents detailed examination of the
geometry of the emission line region or the obscuring dust. We also report the
first detection of the transition-region line C IV 1550 in the spectrum of an
RCB star.Comment: AJ in press (June), 7 figures, 4 table