Figure 2. Analysis-of-Variance periodograms computed using our data obtained between 1994 November and 1995 February. Panel a (top) shows the results for GRO J0422+32 while panel b (bottom) shows the results for the check star (see Fig. 1). The main peak in panel a is found at the frequency 9.424 c/d corresponding to a period of 0.1061 d (with 1-day alias sidelobes). A smaller peak is detected at half this frequency (0.2122 d). The periodogram for the check star illustrates the noise level for a 21 mag object.