(a) Map (colour image) of the spectral index of the 3 mm continuum emission computed from the emission at the minimum and maximum frequencies observed in the GUAPOS survey. (b) Contour map of the 1 cm continuum emission overlaid on the map of the 3 mm free-free continuum emission calculated using the spectral index information (see text). Contour levels range from 1 to 26 in steps of 5 mJy/beam. (c) Same as panel b, for the 3 mm dust continuum emission. The synthesised beam is shown in the bottom-right corner.