Colored curves show strips of the first-moment map of different NH₃ transitions, taken along the major axis of the maser clusters “A” (upper panel) and “B” + “C” (lower panel) . Colored bars along the “Y” axis mark the mean V_LSR of the NH₃ lines. The association color–NH₃ transition is indicated in the upper left corner of the panel. Black dots report the 6.7 GHz masers of the clusters, selecting only the features closely aligned along the cluster major axis. Dot size is proportional to the logarithm of the maser intensity. The linear and quadratic fits to the maser distribution are indicated with a black dashed and black dot-dashed line, respectively. Colored dotted lines show the linear fits to the first-moment strips of the NH₃ transitions.