  Multi-epoch photometry from AllWISE provides the opportunity to investigate
variability at 3.4 and 4.6 microns for most known brown dwarfs. WISE observed
the same patch of sky repeatedly and within a day's time, roughly 12
observations were obtained on a given patch of sky; then, another 12 were
obtained roughly six months later when that patch of sky was again in view. For
most of the sky, AllWISE contains two separate epochs of about a dozen
observations each, although ~30% of the sky has three such epochs available in
AllWISE. With the AllWISE multi-epoch photometry of ~1500 known M, L, T, and Y
dwarfs, I computed the Stetson J Index and quantified variability as a function
of spectral type. I found that the average single-exposure photometric
uncertainty in AllWISE (~0.2 magnitudes) is too large to robustly identify flux
variability smaller than ~20%. However, multi-epoch photometry from AllWISE
remains a useful resource in cases where flux variability is known to be
present with large amplitudes, or for bright nearby objects with lower
photometric uncertainties.
