A FLARE IN THE MIRA X-OPH

Before the observation of the 1914 U Ori eruption, it was considered t hat the Mira stars had only some regular OH variations. With this erup tion, we realized that sometimes flares can occur in this type of star . In the course of an OH Mira star monitoring programme with the Nanca y radio telescope, we have discovered a new eruptive type of OH maser emission in several sources. Especially, in early 1992, we observed a quickly rising 1665 Mhz emission in the Mira X Oph. The main character istics of this flare were: large flux variations independent of the li ght curve; large degree of circular polarization; radial velocity emis sion close to the stellar velocity.