Photometric follow-up of the transiting planet WASP-1b

Abstract

We report on photometric follow-up of the recently discovered transiting planet WASP-1b. We observed two transits with the Wise Observatory 1m telescope, and used a variant of the EBOP code together with the Sys-Rem detrending approach to fit the light curve. Assuming a stellar mass of 1.15 M_sun, we derived a planetary radius of R_p = 1.40 +- 0.06 R_J and mass of M_p = 0.87 +- 0.07 M_J. An uncertainty of 15% in the stellar mass results in an additional systematic uncertainty of 5% in the planetary radius and of 10% in planetary mass. Our observations yielded a slightly better ephemeris for the center 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.