  We observed a secondary eclipse of WASP-33b quasi-simultaneously in the
optical (~0.55 {\mu}m) and the near-infrared (~1.05 {\mu}m) using the 2x8.4 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 dF = 1.03 +/- 0.34 parts per
thousand, corresponding to a brightness temperature of Tb = 3398 +/- 302 K.
Combining previously published data with our new measurement we find the
equilibrium temperature of WASP-33b to be Tb = 3358 +/- 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-33b'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
cannot rule out models with or without a temperature inversion, they do confirm
a high brightness temperature for the planet at short wavelengths. WASP-33b 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.
