Map of the peak velocity of the NH₃ (1, 1) (left panel) and (2, 2) (right panel) inversion transitions fitted as outlined in Sect. 3.1. Crosses indicate the emission peaks of cores C1-a, C1-b, C2, C3, and A2 (see Fig. 1). Solid contours mark the location of the N₂D⁺ cores, (see Fig. 1). In both panels, the dotted contours range from  − 19.5 to  − 16.5 km s^-1, in steps of 0.3 km s^-1, and the ellipse in the bottom left corner shows the VLA synthesised beam.