2007ApJ...660..858M

We present accurate V-band photometry for a planetary transit of OGLE-TR-111 acquired with VIMOS at the ESO Very Large Telescope. The measurement of this transit allows us to refine the planetary radius, obtaining R_p=1.01±0.06 R_J. Given the mass of M_p=0.53 M_J previously measured from radial velocities, we confirm that the density is ρ_p=0.6±0.2 g/cm3. We also revise the ephemeris for OGLE-TR-111-b, obtaining an accurate orbital period P=4.014484±0.000014 days and predicting that the next observable transits would occur around December 2006, and after that only in mid-2008. Even though this period is different from previously published values, we cannot yet rule out a constant period.