Rossiter-McLaughlin effects, or spectroscopic transits, of WASP-20b and WASP-28b. The CORALIE RVs are shown in blue and the HARPS RVs are shown in brown. The Keplerian orbits have been subtracted. For each planet, the observed apparent redshift, followed by an apparent blueshift of similar amplitude, indicate the orbit to be prograde and, probably, aligned with the stellar rotation. The alignment of the orbit of WASP-28b is less certain due to its low impact parameter. The lower precision of the earlier WASP-28 RVs resulted because the sequence started at an airmass of 1.7.