SIMBAD references

We report on some subtle changes which were detected in old IUE low dispersion spectra of the pulsating central star of the planetary nebula K 1-16. Although most of the data were taken more than ten years ago, the improved data reduction techniques and more accurate line identifications that have become available only recently permit measurement of variability in absorption lines. These changes are suspected of being caused by variations of O VI and high-excitation C IV transitions that on low-dispersion spectra are unresolved from interstellar Si II and may also mimic He II lambda-1640 absorption. We compare features in low- and high-resolution spectra of K 1-16 with those found in other PG 1159- and O VI-type central stars.