We analyze a \Delta V \sim - 9 magnitude flare on the newly identified M8 dwarf SDSS J022116.84+194020.4 ( hereafter SDSSJ0221 ) detected as part of the All-Sky Automated Survey for Supernovae ( ASAS-SN ) .
Using infrared and optical spectra , we confirm that SDSSJ0221 is a relatively nearby ( d \sim 76 pc ) M8 dwarf with strong quiescent H \alpha emission .
Based on kinematics and the absence of features consistent with low-gravity ( young ) ultracool dwarfs , we place a lower limit of 200 Myr on the age of SDSSJ0221 .
When modeled with a simple , classical flare light-curve , this flare is consistent with a total U -band flare energy E _ { U } \sim 10 ^ { 34 } erg , confirming that the most dramatic flares are not limited to warmer , more massive stars .
Scaled to include a rough estimate of the emission line contribution to the V band , we estimate a blackbody filling factor of \sim 10–30 % during the flare peak and \sim 0.5–1.6 % during the flare decay phase .
These filling factors correspond to flare areas that are an order of magnitude larger than those measured for most mid-M dwarf flares .