Figure 3. The periodogram of Fig. 2a is plotted here in detail for the small period interval 0.2105 - 0.2135 d (step curve). The scaled (divided by 10) periodogram we gave in Paper I, based on data obtained in 1993 January, February and December, is plotted as a dotted curve. The four thin vertical bars show the possible periods derived by Filippenko et al. from their spectroscopic observations of 1994 November and 1995 January.