XMM-Newton Science Analysis System


omvariability (omvariability-1.4) [xmmsas_20190531_1155-18.0.0]

Variability statistics

The following two variability parameters are computed

• The reduced chi-squared statistic-

  chi= $(\sum_{k=1}^n w_k(c_k-mean))/n-1$,

  where mean is the mean corrected count-rate= $(\sum_{k=1}^n w_kc_k) / \sum_{k=1}^nw_k$

  and

  $w_k=1/ \Delta c^2$

• NSTD The maximum deviation of any source away from the median corrected count-rate of all the sources.