  Learned et. al. proposed that a sufficiently advanced extra-terrestrial
civilization may tickle Cepheid and RR Lyrae variable stars with a neutrino
beam at the right time, thus causing them to trigger early and jogging the
otherwise very regular phase of their expansion and contraction. This would
turn these stars into beacons to transmit information throughout the galaxy and
beyond. The idea is to search for signs of phase modulation (in the regime of
short pulse duration) and patterns, which could be indicative of intentional,
omnidirectional signaling.
  We have performed such a search among variable stars using photometric data
from the Kepler space telescope. In the RRc Lyrae star KIC 5520878, we have
found two such regimes of long and short pulse durations. The sequence of
period lengths, expressed as time series data, is strongly auto correlated,
with correlation coefficients of prime numbers being significantly higher
($p=99.8$\%). Our analysis of this candidate star shows that the prime number
oddity originates from two simultaneous pulsation periods and is likely of
natural origin.
  Simple physical models elucidate the frequency content and asymmetries of the
KIC 5520878 light curve.
  Despite this SETI null result, we encourage testing other archival and future
time-series photometry for signs of modulated stars. This can be done as a
by-product to the standard analysis, and even partly automated.
