Unusually powerful flare activity of the H2O maser feature near a velocity of −60 km s−1 in W49N

Water maser monitoring observations of W49N were carried out with the 22-m Simeiz radio telescope from 2017 May to 2020 February. A series of flares near a high-velocity spectral feature at −60 km s−1 was detected, including a very short duration flare (less than a month) that was very powerful (at its maximum, it reached a flux density of 77 kJy). This flare occurred on top of a less powerful, but longer-lasting flare. A correlation is revealed between the exponential growth of the flux density and the decrease in the linewidth, which is characteristic of the behaviour of a maser in an unsaturated state. In connection with flare phenomena in the framework of the model of close binary massive star systems (CMSSs), we consider the possibility of detecting gravitational waves from CMSSs in the regions of active star formation.