VARIABILITY OF IUE SPECTRA OF THE PULSATING NUCLEUS OF THE PLANETARY-NEBULA K-1-16

We report on some subtle changes which were detected in old IUE low-di spersion 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 identif ications that have become available only recently permit measurement o f variability in absorption lines. These changes are suspected of bein g caused by variations of O VI and high-excitation C IV transitions th at on low-dispersion spectra are unresolved from interstellar Si Il an d 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 P G 1159- and O VI-type central stars,