  We present our analysis of the long cadence Kepler data for the well-studied
Blazhko star RR Lyr, gathered during the first two quarters of the satellite's
observations and covering a total of 127d. Besides being of great importance
for our understanding of RR Lyrae stars in general, these RR Lyr data can be
regarded as a case study for observations of bright stars with Kepler. Kepler
can perform high-precision photometry on targets like RR Lyr, as the saturated
flux is conserved to a very high degree. The Kepler data on RR Lyr are
revolutionary in several respects. Even with long-cadence sampling (one
measurement per 29.4 min), the unprecedented precision (< mmag) of the Kepler
photometry allows the study of the star's extreme light curve variations in
detail. The multiplet structures at the main frequency and its harmonics,
typical for Blazhko stars, are clearly detected up to the quintuplets. For the
first time, photometric data of RR Lyr reveal the presence of half-integer
frequencies, linked to a period doubling effect. This phenomenon may be
connected to the still unexplained Blazhko modulation. Moreover, with three
observed Blazhko cycles at our disposal, we observe that there is no exact
repetition in the light curve changes from one modulation cycle to the next for
RR Lyr. This may be due to additional periodicities in the star, or to
transient or quasi-periodic changes.
