2007MNRAS.376.1296S

We report on photometric follow-up of the recently discovered transiting planet WASP-1b. We observed two transits with the Wise Observatory 1-m telescope, and used a variant of the Eclipsing Binary Orbit Program (ebop) code together with the Sys-Rem detrending approach to fit the light curve. Assuming a stellar mass of 1.15M_☉, we derived a planetary radius of R_p= 1.40 ±0.06R_Jand mass of M_p= 0.87±0.07M_J. An uncertainty of 15 per cent in the stellar mass results in an additional systematic uncertainty of 5 per cent in the planetary radius and of 10 per cent in planetary mass. Our observations yielded a slightly better ephemeris for the centre of the transit: T_c[HJD] = (2454013.3127±0.0004) + N_tr(2.51996±0.00002). The new planet is an inflated, low-density planet, similar to HAT-P-1b and HD209458b.