OSCILLATOR STRENGTH CALCULATIONS IN CE-III - APPLICATION TO HD-200311

We have calculated oscillator strengths for the Ce III spectrum using the atomic structure code of R. D. Cowan. The results are used to dete rmine the cerium abundance in the silicon star HD 200311. From the dom inant ion (Ce++), we find an excess of 5 dex. We find very good agreem ent with the abundance obtained from Ce II lines. While uncertainties remain with the oscillator strengths, it is no longer possible to assu me that underionization could explain the extraordinary abundance exce ss of the lanthanide cerium in this hot, magnetic, chemically peculiar star.