ALMA band 6 continuum maps of five red supergiants in RSGC1: F01 (upper left), F02 (upper right), F03 (middle left), F04 (middle right), and F13 (bottom left). Contours (in orange) are indicated at [50, 60, 90, and 99]% of the peak continuum emission (see Table A.1). The ordinate and co-ordinate axis give the offset of the right ascension and declination, respectively, with respect to the peak of the SiO v = 3 J = 5-4 zeroth moment map. The ALMA synthesised beam is shown as a white ellipse in the lower right corner of each panel.