Velocity fields of four inversion transitions of NH₃, (6,6), (9,9), (10,10), and (13,13), as measured towards NGC 7538 IRS1 with the JVLA B-Array. In each panel, the positions of the 6.7 GHz CH₃OH masers (black-circled, colored dots) are overlaid on the NH₃ image. The conversion code between colors and V_LSR is indicated in the wedge to the right side of the upper right panel. Dot size is proportional to the logarithm of the maser intensity. Dotted contours have the same meaning as in Fig. 1. In the bottom right panel, the labels of the maser clusters and the names of the main 1.3 cm continuum peaks are given.