Ground-based secondary eclipse detection of the very-hot Jupiter OGLE-TR-56b

We report on the detection of the secondary eclipse of the very-hot Jupiter OGLE-TR-56b from combined z'-band time series photometry obtained with the VLT and Magellan telescopes. We measure a flux decrement of 0.0363 +/- 0.0091% from the combined Magellan and VLT datasets, which indicates a blackbody brightness temperature of 2718(-107)(+127) K, a very low albedo, and a small incident radiation redistribution factor, indicating a lack of strong winds in the planet's atmosphere. The measured secondary depth is consistent with thermal emission, but our precision is not sufficient to distinguish between a black-body emitting planet, or emission as predicted by models with strong optical absorbers such as TiO/VO. This is the first time that thermal emission from an extrasolar planet is detected at optical wavelengths and with ground-based telescopes.