This figure shows the variation in light (the light curve) caused by the transit of the planet WASP-3b. These data originate from observations made April 18, 2010. Individual data points are shown as dots. The brightness of the star in millimagnitudes (an astronomical unit of brightness) is plotted against observing time in hours (0.0 marks the center of the transit). The red line is the best fit to the data showing the transit start (or ingress) from first to second tick-marks, mid-transit (3rd tick-mark) and the transit end (egress) from the 4th to the 5th tick-mark.