ATCA wide-band images. Top: the pixel image shows the intensity distribution of the two central channels covering the NH₃(1,1) line. Bottom: the pixel image of the channel containing the (2,2) line. The contour map superimposed on both images represents the true 1.3 cm continuum emission, i.e. wide-band channels without ammonia line contamination. The positions of Cha-MMS1a and the Spitzer 24 μm maximum are marked with a plus sign and a triangle, respectively.