We observed a secondary eclipse of WASP-33 b quasi-simultaneously in the optical ( \sim 0.55 \mu m ) and the near-infrared ( \sim 1.05 \mu m ) using the 2 \times 8.4 m Large Binocular Telescope .
WASP-33 is a \delta Scuti star pulsating with periods comparable to the eclipse duration , making the determination of the eclipse depth challenging .
We use previously determined oscillation frequencies to model and remove the pulsation signal from the light curves , isolating the secondary eclipse .
The determined eclipse depth is \Delta F = 1.03 \pm 0.34 parts per thousand , corresponding to a brightness temperature of T _ { B } = 3398 \pm 302 K. Combining previously published data with our new measurement we find the equilibrium temperature of WASP-33 b to be T _ { B } = 3358 \pm 165 K. We compare all existing eclipse data to a blackbody spectrum , to a carbon-rich non-inverted model and to a solar composition model with an inverted temperature structure .
We find that current available data on WASP-33 b ’ s atmosphere can be best represented by a simple blackbody emission , without the need for more sophisticated atmospheric models with temperature inversions .
Although our data can not rule out models with or without a temperature inversion , they do confirm a high brightness temperature for the planet at short wavelengths .
WASP-33 b is one of the hottest exoplanets known till date , and its equilibrium temperature is consistent with rapid reradiation of the absorbed stellar light and a low albedo .