The Rapid Far-ultraviolet Variability of ET And and Its Rotational Period

Evidence is presented that the far-ultraviolet flux of ET And (A0Vp SiSr) recorded by the International Ultraviolet Explorer was variable over a timescale of about one hour on 1979 August 7. In contrast, the spectra taken over 9 hr on 1979 August 3 do not show any flux variability. This behavior is discussed using the light curve of ET And recently acquired with TESS. We also derive a refined rotational period, P_rot = 1.618845 ± 0.000006 days, from the detrended TESS light curve.