Structure of the water maser emission. Colored dots and the two dashed lines and black-yellow stars have the same meaning as in Fig. 1. Colored squares, black segments overlaid on the squares, and dotted contours have the same meaning as in Fig. 2. The emission of the water maser clusters 1–4 is shown in the corresponding insets. To catch weaker maser features, plots of the maximum emission over the cluster velocity range are presented. The beam of the global VLBI observations has a FWHM size of 0.6 au and it is too small to be shown in the insets.