Infrared Observations during the Secondary Eclipse of HD 209458b. I. 3.6 Micron Occultation Spectroscopy Using the Very Large Telescope

Abstract

We search for an infrared signature of the transiting extrasolar planet HD 209458b during secondary eclipse. Our method, which we call ‘occultation spectroscopy, ’ searches for the disappearance and reappearance of weak spectral features due to the exoplanet as it passes behind the star and later reappears. We argue that at the longest infrared wavelengths, this technique becomes preferable to conventional ‘transit spectroscopy’. We observed the system in the wing