Spectra of Mg ix, Al x, and Si xi Isoelectronic with Be i

In this work, we extend the previous analysis of the Mg ix, Al x, and Si xi spectra. Classifications and wavelengths are given for 90 new transitions in the range 30–60 Å. Wavenumbers are given for 60 new levels. The analysis is given for several cases of unresolved spectral lines. The term structure of these ions is discussed and term values are given for several experimentally uncorrelated groups of terms.