Long term light curve variations of the Kepler Cepheid V 1154 Cyg

We present a period analysis of the light curve and its Fourier parameters of the bright Cepheid V1154 Cyg (P=4.925454 days) based on the observations by the Kepler space telescope. Fourier parameters R21, R31 clearly indicate variations with a period of 158.2 ± 1 days (more than 5σ peak in the power spectrum) with a very small amplitude (0.265-0.275 for R21, 0.065-0.071 for R31) making impossible to detect it with ground- based observations. Finally we discuss that this effect is similar to the Blazhko effect in RR Lyrae stars.