Saturn continuum flux density images at 230 GHz. (Top) Saturn continuum image as observed with ALMA on January 14, 2012. (Center) Simulated continuum image in the conditions of the January 2012 observations. (Bottom) Residuals (observation – model) showing the overall good agreement between model and observations, especially at the limb. In all panels, the 1-bar level is shown with the black ellipse, the planet rotation axis is displayed with a dashed black line, and isolatitudes are indicated by gray contours. The expected position of the A and B rings is depicted by the gray filled area and the beam is illustrated with a white filled ellipse.