STUDY OF THE WATER MASER IN THE SOURCE ON 1

Results from observations of the H2O-maser emission in ON1, associated with a star-forming region, are reported. The observations were condu cted with the RT-22 radio telescope of the Radio Astronomical Station (Lebedev Physical Institute, Russian Academy of Sciences) at Pushchino over the period from 1981 to 1993. No strong outburst was recorded. A periodic component in the integrated-flux variations (nearly sinusoid al in form) with a period of about ten years and a small-amplitude non periodic flare-type component were detected. The variability may be ca used by the stellar wind, which reflects the state of the central star at the initial stage of its evolution. The model of the H2O maser in ON1. is justified, in which the maser condensations produce a ring. Th e ring must have expansion and rotation velocities of about 8 and 2.5 km s(-1), respectively.