High-precision photometry by telescope defocusing - V.WASP-15 and WASP-16

We present newphotometric observations ofWASP-15 andWASP-16, two transiting extrasolar planetary systems with measured orbital obliquities but without photometric follow-up since their discovery papers. Our new data for WASP-15 comprise observations of one transit simultaneously in four optical passbands using GROND on the MPG/European Southern Observatory (ESO) 2.2 m telescope, plus coverage of half a transit from DFOSC on the Danish 1.54 m telescope, both at ESO La Silla. ForWASP-16 we present observations of fourcomplete transits, all from the Danish telescope. We use these new data to refine the measured physical properties and orbital ephemerides of the two systems. Whilst our results are close to the originally determined values forWASP-15, we find that the star and planet in theWASP-16 system are both larger and less massive than previously thought. ©2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society