tokens: to the total flux. Thus we believe the signal to belong to the visual companion star, which has a temperature of 5430 K. A rotation period of 4.6 d is fairly rapid for a star of T eff = 5430 K, which may imply a young age for the system, consistent with our bagemass analysis in Section 6 . 5 COMBINED MCMC ANALYSIS We use a Markov chain Monte Carlo (MCMC) approach to fit the combined photometric and radial velocity data, as well as investigate the RM effect. We follow methods very similar to Temple et al. ( 2018 , 2019 ), whereby we conduct both an RM analysis and a tomographic analysis and adopt the better constrained solution. The RM analysis involves detecting the line profile distortions as an apparent overall shift in radial velocity measurements (e.g. Triaud 2017 ), whereas the tomographic analysis requires one to directly map the motion of the distortion caused by the occulting body across the line profiles as a function of phase (e.g. Brown et al. 2017 ; Temple et al. 2017 ). The code we use is described by Collier Cameron et al. ( 2007 , 2010 ) and Pollacco et al. ( 2008 ). The combined photometric and RV fitting determines the orbital period P , the epoch of mid-transit T c , the planet-to-star area ratio ( R p / R ⋆ ) 2 , the transit duration T 14 , the impact parameter b , the stellar reflex velocity semi-amplitude K 1 , and the barycentric system velocity γ. We use the value of T eff obtained in the dilution correction as input, and interpolate four-parameter limb darkening coefficients from the Claret ( 2000 , 2004 ) tables in each step using the current value of T eff . We use the stellar radius obtained in Section 4.2 (1.17 ± 0.08 ) as a prior to constrain stellar parameters. In the fit we present, we have assumed that the orbit is circular, as one would expect a hot Jupiter to circularize on a time-scale shorter than its lifetime (Pont et al. 2011 ). However, a further fit was carried out to test this assumption, leading to an upper limit of e 0.27 (95 per cent confidence). We display the photometry and best-fitting transit model in Fig. 2 . Figure 2. The WASP discovery photometry (top) and follow-up transit light curves (bottom) with the best-fitting model shown in blue (see Section 5 ). The data for the three follow-up light curves, prior to the dilution correction, are available online as supporting material . The RM fit and Doppler tomography give values for v sin i ⋆ , λ, and the system γ-velocity. We use the calibrations of Hirano et al. ( 2011 ) to fit the RM effect. For Doppler tomography, we assume a Gaussian profile for the perturbation to the stellar-line profiles and fit the intrinsic full width at half maximum (FWHM) of the perturbation, v FWHM . Both methods also provide an additional constraint on the impact parameter b , although the tomographic method fits this quantity more directly. We estimate the start value for γ by fitting a Gaussian profile to the CCFs. We also apply the spectral v sin i ⋆ as a
ner_tags: O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Formula I-Formula I-Formula I-Formula I-Formula O O O O O O O O O O O O O O O O O O O O B-Model O O O O B-Model I-Model I-Model I-Model B-Model O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation O B-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O B-Citation O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O B-Formula I-Formula I-Formula I-Formula I-Formula I-Formula I-Formula I-Formula O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation O B-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-EntityOfFutureInterest I-EntityOfFutureInterest O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Survey O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-ObservationalTechniques I-ObservationalTechniques O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O B-Model I-Model O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Model I-Model O O O O O O O O O O O O O O