ESO Large Programme 666 on OGLE transits: I. Accurate radius of the planets OGLE-TR-10b and OGLE-TR-56b with VLT deconvolution photometry

7 pages, 6 figures; submitted to Astronomy & AstrophysicsTransiting planets are essential to study the structure and evolution of extra-solar planets. For that purpose, it is important to measure precisely the radius of these planets. Here we report new high-accuracy photometry of the transits of OGLE-TR-10 and OGLE-TR-56 with VLT/FORS1. One transit of each object was covered in Bessel V and R filters, and treated with the deconvolution-based photometry algorithm DECPHOT, to ensure accurate millimagnitude light curves. Together with earlier spectroscopic measurements, the data imply a radius of 1.26 +- 0.07 RJ for OGLE-TR-10b and 1.30 +- 0.06 RJ for OGLE-TR-56b. A re-analysis of the original OGLE photometry resolves an earlier discrepancy about the radius of OGLE-TR-10. Our study confirms both planets as inflated hot Jupiters, with large radii comparable to that of HD 209458 and at least two other recently discovered transiting gas giants