Light curves without self-absorption and electron cooling, leaving only critical frequency ν_m. The light curves are calculated at observer frequencies 1.4 × 10⁹ Hz (upper light curves) and 5 × 10¹⁷ Hz (lower light curves), to ensure they are on different sides of ν_m. Results for 5 × 10¹⁷ Hz have been multiplied by a scaling factor of 100. Aside from results from spherical flow, results from hard-edged jets with half-opening angles of 10°, 15° and 20° are plotted. The new predicted jet break times (equation 7 in the text) are indicated by dots connected to the lower edge of the plot, old predictions (equation 4 in the text) connect to the upper edge of the plot.