Searching for Weather in Brown Dwarfs
  We have used an innovative tuneable filter technique to carry out a search for the variability signatures of meterological processes in the atmospheres of two nearby brown dwarfs. We find no evidence for variability in the L-type brown dwarf DENIS-PJ1228-1547 in an observations spanning approximately half a rotation period (3 hours), and evidence for variability in the M-type brown dwarf LP 944-20 in multiple observations spanning approximately one third of a rotation period (1.5 hours). 
C.G.Tinney & A.J.Tolley