  We present an analysis of the KOI-13.01 candidate exoplanet system included
in the September 2011 Kepler data release. The host star is a known and
relatively bright $(m_{\rm KP} = 9.95)$ visual binary with a separation
significantly smaller (0.8 arcsec) than the size of a Kepler pixel (4 arcsec
per pixel). The Kepler light curve shows both primary and secondary eclipses,
as well as significant out-of-eclipse light curve variations. We confirm that
the transit occurs round the brighter of the two stars. We model the relative
contributions from (i) thermal emission from the companion, (ii) planetary
reflected light, (iii) Doppler beaming, and (iv) ellipsoidal variations in the
host-star arising from the tidal distortion of the host star by its companion.
Our analysis, based on the light curve alone, enables us to constrain the mass
of the KOI-13.01 companion to be $M_{\rm C} = 8.3 \pm 1.25M_{\rm J}$ and thus
demonstrates that the transiting companion is a planet (rather than a brown
dwarf which was recently proposed by \cite{b7}). The high temperature of the
host star (Spectral Type A5-7V, $T_{\rm eff} = 8511-8020$ K), combined with the
proximity of its companion KOI-13.01, may make it one of the hottest exoplanets
known, with a detectable thermal contribution to the light curve even in the
Kepler optical passband. However, the single passband of the Kepler light curve
does not enable us to unambiguously distinguish between the thermal and
reflected components of the planetary emission. Infrared observations may help
to break the degeneracy, while radial velocity follow-up with $\sigma \sim$ 100
m s$^{-1}$ precision should confirm the mass of the planet.
