VLT transit and occultation photometry for the bloated planet CoRoT-1b ^*,**

¹ Institut d'Astrophysique et de Géophysique, Université de Liège, Allée du 6 Août 17, Bât. B5C, Liège 1, Belgium e-mail: michael.gillon@ulg.ac.be
² Observatoire de Genève, Université de Genève, 51 Chemin des Maillettes, 1290 Sauverny, Switzerland
³ Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001, USA
⁴ School of Physics and Astronomy, University of St. Andrews, North Haugh, Fife, KY16 9SS, UK
⁵ Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK
⁶ Laboratoire d'Astrophysique de Marseille (UMR 6110), 38 rue Frédéric Joliot-Curie, 13388 Marseille, France

Received: 30 March 2009
Accepted: 26 May 2009

Abstract

We present VLT eclipse photometry for the giant planet CoRoT-1b. We observed a transit in the R-band filter and an occultation in a narrow filter centered on 2.09 μm. Our analysis of this new photometry and published radial velocities, in combination with stellar-evolutionary modeling, leads to a planetary mass and radius of 1.07 M_Jup and 1.45 R_Jup, confirming the very low density previously deduced from CoRoT photometry. The large occultation depth that we measure at 2.09 μm (0.278) is consistent with thermal emission and is better reproduced by an atmospheric model with no redistribution of the absorbed stellar flux to the night side of the planet.