Left frame: contours show the velocity-integrated NH₃(3, 3) transition emission from NGC 253 integrated from 144 km s^-1 to 341 km s^-1. Overlain is the gray-scale image of the continuum at 23.7 GHz with the upper bar providing the flux density scale in mJy beam^-1. The contour levels are −3, 3, 6, 12, 18, 24 times 1.2 mJy km s^-1 beam^-1. Right upper frame: integrated NH₃ (3, 3) spectrum. Right lower frame: ammonia (3, 3) transition spectra integrated over the six clouds of NGC 253 identified by the boxes in the velocity integrated NH₃ (3, 3) emission (left panel).