target and reference stars are the same. This may not be the case if the reference stars are significantly brighter or fainter than the target. The observations of include a number of reference stars with similar brightness, however and are brighter than their reference stars by $\Delta \mathrm{mag}\sim1-2$. The method also assumes that white noise is the only noise contribution. Reference stars with obvious variability are identified by eye and removed, but there may be residual time-correlated noise in the target and reference stars if the systematics were not adequately removed by Equation \[eq:pixelphase\]. If this is the case the significance thresholds may be slightly underestimated. Since none of the reference star periodograms in Figures \[fig:2M0045\_full\_lc\], \[fig:2M0501\_full\_lc\] and \[fig:2M1425\_full\_lc\] peak above the estimated significance thresholds and none of the reference star periodograms peak at periods similar to the periods of our variable targets, it is likely that the contributions from non-white noise do not affect our ability to identify variability using the Lomb-Scargle periodogram. Additionally, since periodic variability is independently recovered in both channels for and , it is likely that the variability is astrophysical in nature. ]{}

![image](contour2M1425-36_ch1_discrete-eps-converted-to.pdf) ![image](contour2M1425-36_ch2_discrete-eps-converted-to.pdf)

Variability Detection Using the Bayesian Information Criterion {#sec:BIC}
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[We 