Long-term variables of HR 8752 in V, B, and U in 1942–1994. The arrows at the bottom indicate dates of spectroscopic observations by Smolinski et al. (1989), taken in 1969 and 1970, and between 1979 and 1982; see also de Jager (1998, Figs. 9 and 10 in Sect. 7). These spectroscopic observations signalled the presence of an enhanced mass-loss episode and a massive eruption in 1973 (arrow), which was not photometrically recorded (Nieuwenhuijzen et al. 2012). We note that after 1979 (∼JD 24 44000) only V declined; see text.