OH and H2O maser variations in W33B
  The active star-forming region W33B is a source of OH and H2O maser emission
located in distinct zones around the central object. The aim was to obtain the
complete Stokes pattern of polarised OH maser emission, to trace its
variability and to investigate flares and long-term variability of the H2O
maser and evolution of individual emission features. Observations in the OH
lines at a wavelength of 18 cm were carried out on the Nan\c{c}ay radio
telescope (France) at a number of epochs in 2008--2014; H2O line observations
(long-term monitoring) at a wavelength of 1.35 cm were performed on the
22-metre radio telescope of the Pushchino Radio Astronomy Observatory (Russia)
between 1981 and 2014. We have observed strong variability of the emission
features in the main 1665- and 1667-MHz OH lines as well as in the 1612-MHz
satellite line. Zeeman splitting has been detected in the 1665-MHz OH line at
62 km/s and in the 1667-MHz line at 62 and 64 km/s. The magnetic field
intensity was estimated to be from 2 to 3 mG. The H2O emission features form
filaments, chains with radial-velocity gradients, or more complicated
structures including large-scale ones. Long-term observations of the hydroxyl
maser in the W33B region have revealed narrowband polarised emission in the
1612-MHz line with a double-peak profile characteristic of Type IIb
circumstellar masers. The 30-year monitoring of the water-vapour maser in W33B
showed several strong flares of the H2O line. The observed radial-velocity
drift of the H2O emission features suggests propagation of an excitation wave
in the masering medium with a gradient of radial velocities. In OH and H2O
masers some turbulent motions of material are inferred.
