Left panel: temperature distribution along the ISF overlaid with integrated intensity contours as in the left panel of Fig. 1. Most of the temperatures are about or below 20 K. Temperatures exceed 40 K at several positions. There the NH₃ (2, 2) lines are even stronger than those of NH₃ (1, 1) (see the lower right panel). Top right panel: histogram of the rotation temperatures derived from NH₃. Lower right panel: the NH₃ (1, 1) (black profiles) and NH₃ (2, 2) (red profiles) spectra around the Trapezium. The reference position corresponds to RA: 05:35:14, DEC: −05:22:24(J2000), the spacing is one arcminute.