Detection of a strong stellar flare from EUVE J1438-432

We present extreme-ultraviolet (EUV) observations of a strong flare from EUVE J1438-432, a source serendipitously detected with the Extreme Ultraviolet Explorer (EUVE) Right Angle Program. The flare was detected in the Lexan/boron (100 A) band and showed a 16-fold increase over quiescent emission with a rise time of ~10 ks and a decay time of ~40 ks. Optical spectroscopy of objects within the EUVE pointing uncertainty circle revealed a pair of late-type stars (WT 486 and WT 487) both showing Balmer series in emission; either star is a good candidate for production of the flare. The peak luminosity of the flare is 5.7x10^29 ergs s^-1 with a total energy of ~5x10^33 ergs. The flare energetics are about 2 orders of magnitude lower than the large EUV flare detected from AU Mic in 1992, but similar to other EUV-detected flares from late-type stars.