Fixed-frequency fits give second-harmonic bounds below 4.4 ppm for KIC 8164262 in Kepler DR25

We test a coherent signal at twice the known strong oscillation frequency of KIC 8164262 with 18 public Kepler release 25 quarters. Full-mission fitted semi-amplitudes are 1.64 ppm in corrected flux and 0.81 ppm in aperture flux. Approximate conditional 95 percent coefficient ellipses contain zero in both mission halves. Full-mission upper values stay below 4.4 ppm across five orbital-mask and baseline choices and three residual group lengths. Nearby frequencies give larger amplitudes in many comparisons. These are fixed-frequency noise-model bounds, not limits on all changing harmonics or general stellar nonlinearity. A simple temperature-to-light model predicts a signal below the tested sensitivity. We report no new planet, stellar mode, or independent telescope confirmation. Code, accepted data, exact source hashes, all fits, numerical checks, and reproduction steps are included.

Kepler · KIC 8164262 · second harmonic · tidal oscillations · null result