  We have conducted multi-epoch synthesis imaging of 2 and 3 millimeter (mm)
continuum emission and near infrared K band 2.2 um imaging of a flare event in
January 2003 that occurred on the young stellar object GMR-A which is suggested
to be a weak-line T Tauri star in the Orion cluster. Our mm data showed that
the flare activity lasted at least over 13 days, whereas the K-band magnitude
did not change during this event. In addition, we have succeeded in detecting
short time variations of flux on the time scales of 15 minutes. The total
energy of the flare is estimated to be 10^{35-36} erg, which makes it one of
the most energetic flares reported to date. Comparing the mm continuum
luminosities with reported X-ray luminosities, we conclude that the mm flare
was similar in nature to solar and other stellar flares. Our results will be a
crucial step toward understanding magnetically induced stellar surface
activities in T Tauri stars.
