The HST Quasar Absorption Line Key Project XII. The Unusual Absorption   Line System in the Spectrum of PG 2302+029 ---Ejected or Intervening?
  We report the discovery of a high-ionization broad absorption line system at a redshift of z_abs=0.695 in the spectrum of the z_em=1.052 radio-quiet quasar PG 2302+039. Broad absorption with FWHM from 3,000 to 5,000 km/s is detected from C IV, N V, and O VI in HST Faint Object Spectrograph spectra of the quasar. A narrow line system (FWHM approximately 250 km/s) at z_abs=0.7016 is resolved from the broad blend and includes absorption by Ly-alpha and the C IV, N V, and O VI doublets. No absorption by low-ionization metal species (e.g. Si II and Mg II) is detected in the HST or ground-based spectra for either the broad or the narrow system. The centroids of the broad system lines are displaced by approximately 56,000 km/s to the blue of the quasar's broad emission lines. The reddest extent of the broad line absorption is more than 50,000 km/s from the quasar. The properties of this system are unprecedented whether it is an intervening or an ejected system. 
B. T. Jannuzi, G. F. Hartig, S. Kirhakos, W. L. W. Sargent, D. A.   Turnshek, R. J. Weymann, J. N. Bahcall, J. Bergeron, A. ...