Discrepancies between calculated and observed Fexvii and Nixix solar coronal lines

We extend the 36-levels model atom Fe⁺¹⁶ of Loulergue and Nussbaumer (1973) to a 51-levels atom includingn=4 configuration. Our earlier conclusion that relative intensities among the Fexvii lines are not sufficiently sensitive to variations in electron densities and electron temperature to deduce these parameters from observed intensity ratios still holds. Discrepancies between calculated and observed relative intensities in Fexvii and Nixix are attributed to blends or misidentifications.Paper presented at the I.A.U. Colloquium No. 27 on UV and X-Ray Spectroscopy of Astrophysical and Laboratory Plasmas, Cambridge, Mass., U.S.A, 9–11 September 1974.