Kuiper test for X-ray variability. Black, gray, and blue lines show the cumulative distribution function (CDF) computed from the source, background, and contaminant apertures, respectively. CDFs were constructed by summing counts in time. Each CDF was compared to a constant flux (red dashed line). The resulting Kuiper scores and p-values are shown. P-values indicate the probability that each observed CDF is consistent with a constant flux. The results are summarized in Table 2.