After examining ultraviolet IUE spectra of 18 QSOs with z > 0.35, we find that one object, 3C 232 (z = 0.533), stands out as exhibiting highly unusual spectral and continuum variability. The H 1-Lya shows at least 50% variability on a time scale of roughly a month, while the ultraviolet continuum exhibited approximately a factor of 2 decrease in a day. The magnitude of the UV continuum variability is reminiscent of that seen in the optically violent variables at visual wavelengths. Several spectral features at wavelengths shortward of H I-Lya in the rest frame are identified. A brief discussion COJ?lparing the spectrum of 3C 232 with those of other QSOs in our IUE sample at wavelengths shortward of 1216 A is also presented.
Bruhweiler, F.C., Kafatos, M., Sofia, U.J. (1986) The Unusual Ultraviolet Variability of the QSO 3C 232, The Astrophysical Journal, 303: L31-L35. doi: 10.1086/184647