  A 3D maser model has been used to perform an inverse problem on the light
curves from three high-amplitude maser flares, selected on the basis of
contemporaneous infra-red observations. Plots derived from the model recover
the size of the maser cloud, and two parameters linked to saturation, from
three observational properties of the light curve. Recovered sizes are
consistent with independent interferometric measurements. Maser objects
transition between weak and moderate saturation during a flare.
