Temperature (upper panels) and uncertainty (lower panels) maps of the 20 km s^-1 cloud (contours as in Fig. E.1). Upper limits of the temperatures are marked with Xs. The corresponding pixels in the uncertainty maps are blanked. The purple squares present the areas over which the emission of the main H₂CO line was integrated to determine the line width, as well as the average temperature (see Sect. 5.3). The circle in the lower left corner shows the 33″ beam.