a) The CORALIE (blue circles) and HARPS (green diamonds) RVs of WASP-22 from M10, and the HARPS RVs from this paper (brown diamonds). b) An expansion of the region around the spectroscopic transit, as measured by HARPS on 2009 Nov. 19. c) The transit light curves, from top to bottom, obtained by TRAPPIST on 2010 Nov. 18 and 2010 Dec. 2 through an I+z filter and by EulerCam on 2010 Dec. 2 through a Gunn r filter. The data obtained by TRAPPIST on 2010 Dec. 2 prior to the meridian flip are denoted by green triangles and blue dots denote the data obtained post-flip. In each panel, the data are phase-folded on the ephemeris given in Table 3 and the best-fitting models of Sect. 3 are superimposed.