Fig. 1. Plot of the photometric variations during a cometary occultation in red ( Å, thick solid line) and in blue ( Å, thick short-dashed line). The insert is a view from the top when the comet is crossing the line of sight () at the periastron. The production rate is kg s-1 at 1 AU. The scattered light is given by the top thin lines, the extinction by the bottom thin lines (long-dashed line for Å; dotted line for Å). The total variation is plotted with the thick lines. This light curve presents the very specific "rounded triangular" shape observed in the majority of simulations of cometary occultations. The difference between the variation in the blue and in the red is negligible and less than 1%.