Maps of the (mean squared) residual (left panel) and best-fit central mass (right panel) obtained by fitting the curve to the 6.7 GHz maser data in G16.59 − 0.05. Colours give the map value, with the value-color conversion code given in the wedge on the right side of the panels. The values reported in the wedge are in units of arcsec⁶ and solar mass (M_⊙) for the left and right panels, respectively. In both panels, positions are given relative to the center of motion of the 6.7 GHz masers (as defined in SMC1). To better compare the two maps, in both panels white contours report the same levels of fit (mean squared) residual. The plotted levels are from 7    ×    10^-6 arcsec⁶ (10% higher than the minimum fit residual) to 1.6    ×    10^-3 arcsec⁶, stepped by a factor of 2. The spatial distribution of the 6.7 GHz maser features is indicated with white dots.