TIME VARIATIONS OF THE ON2 WATER MASER SPECTRUM DURING 1981-1995

Results of observations at 22.2 GHz of the water maser source ON2 carr ied out at the Pushchino RT-22 radio telescope during 1981-1995 are pr esented. The long-time regular observations of ON2 show that the time interval between the two high levels of the integrated H2O flux densit y is more than 20 years. The flare component of the variability of tot al flux as well as strong hares of some features were not detected. Th e emission is concentrated, basically, in two spectrally separated gro ups of features. The observed anticorrelation of the fluxes of these g roups was manifested only in the period of minimum activity of the H2O maser. It seems that the transition of the maser takes place from the unsaturated state to a partly saturated one and vice versa. The varia bility of the maser emission has a global character for ON2 and may be caused by non-stationary physical processes at the early stages of st ellar evolution.