  Kepler-13Ab (= KOI-13.01) is a unique transiting hot Jupiter. It is one of
very few known short-period planets orbiting a hot A-type star, making it one
of the hottest planets currently known. The availability of Kepler data allows
us to measure the planet's occultation (secondary eclipse) and phase curve in
the optical, which we combine with occultations observed by warm Spitzer at 4.5
mic and 3.6 mic and a ground-based occultation observation in the Ks band (2.1
mic). We derive a day-side hemisphere temperature of 2,750 +- 160 K as the
effective temperature of a black body showing the same occultation depths.
Comparing the occultation depths with one-dimensional planetary atmosphere
models suggests the presence of an atmospheric temperature inversion. Our
analysis shows evidence for a relatively high geometric albedo, Ag= 0.33 +0.04
-0.06. While measured with a simplistic method, a high Ag is supported also by
the fact that the one-dimensional atmosphere models underestimate the
occultation depth in the optical. We use stellar spectra to determine the
dilution, in the four wide bands where occultation was measured, due to the
visual stellar binary companion 1.15 +- 0.05" away. The revised stellar
parameters measured using these spectra are combined with other measurements
leading to revised planetary mass and radius estimates of Mp = 4.94 - 8.09 Mjup
and Rp = 1.406 +- 0.038 Rjup. Finally, we measure a Kepler mid-occultation time
that is 34.0 +- 6.9 s earlier than expected based on the mid-transit time and
the delay due to light travel time, and discuss possible scenarios.
