WASP-107b discovery data. Caption as for Fig. 1. The planet appears to have passed over a star spot during the transit of 2013 Feb. 18, with a bump more evident in the lightcurve from EulerCam (Gunn r) than TRAPPIST (Sloan z). The difference is expected due to the bluer passband employed by EulerCam, in which the contrast between star spots and the surrounding photosphere will be greater. Also, the diameter of the TRAPPIST telescope is half that of the Euler telescope (0.6 m versus 1.2 m), so the data are noisier. Data partioning due to TRAPPIST’s meridian flips are indicated by vertical dashed lines.