  HD 15082 (WASP-33) is the hottest and fastest rotating star known to harbor a
transiting extrasolar planet (WASP-33b). The lack of high precision radial
velocity (RV) data stresses the need for precise light curve analysis and
gathering further RV data. By using available photometric and RV data, we
perform a blend analysis, compute more accurate system parameters, confine the
planetary mass and attempt to cast light on the observed transit anomalies. We
combine the original HATNet observations and various followup data to jointly
analyze the signal content and extract the transit component and use our RV
data to aid the global parameter determination. The blend analysis of the
combination of multicolor light curves yields the first independent
confirmation of the planetary nature of WASP-33b. We clearly identify three
frequency components in the 15-21 1/day regime with amplitudes 7-5 mmag. These
frequencies correspond to the delta Scuti-type pulsation of the host star. None
of these pulsation frequencies or their low-order linear combinations are in
close resonance with the orbital frequency. We show that these pulsation
components explain some but not all of the observed transit anomalies. The
grand-averaged transit light curve shows that there is a ~1.5 mmag brightening
shortly after the planet passes the mid-transit phase. Although the duration
and amplitude of this brightening varies, it is visible even through the direct
inspections of the individual transit events (some 40-60% of the followup light
curves show this phenomenon). We suggest that the most likely explanation of
this feature is the presence of a well-populated spot belt which is highly
inclined to the orbital plane. This geometry is consistent with the inference
from the spectroscopic anomalies. Finally, we constrain the planetary mass to
M_p=3.27+/-0.73 M_J by using our RV data collected by the TRES spectrograph.

Earth and Planetary Astrophysics