Torque noise power density spectrum of SGR 1806−20. The squares and circles denote measurements made with the frequency and phase‐connected data, respectively. The data shown here have been corrected for biases introduced by the analysis method (see text for details). The errors on the power estimates denote the 68% confidence intervals that were derived from the Monte Carlo simulation. The horizontal bars give the log frequency rms of the estimator response. The power levels expected from measurement noise are much lower than the power measured from the source variability. The dashed line denotes the best power‐law fit to the data.