An early shape fit leaves a 60 ppm RMS mismatch in selected later Kepler data for KIC 8462852

We test the known 0.88-day signal near KIC 8462852 in Kepler release 25. A three-harmonic shape from quarters 9 to 11 leaves a 59.9 ppm RMS mismatch in quarters 12 and 13, after setting amplitude and phase from the fundamental in each later quarter. The primary frequency is 1.1361 cycles per day. A fixed-frequency residual-block test gives a conditional tail fraction of 0.007. All 72 tested choices of frequency, flux product, baseline and block length give fractions below 0.05, but some are close to that value. These choices share observations and are not independent tests. The second-harmonic to fundamental amplitude ratio drops from 0.70 to 0.74 in the early raw flux to 0.046 in quarter 13. The test challenges a restricted fixed-shape model. It does not prove a change in the source. Frequency drift, beating, aperture response and processing errors remain possible. No new planet or periodic signal is found. Independent instrument confirmation is absent. Code, aggregate results, figures, hashes and separate-scratch retrieval steps are included.

astronomy · Kepler · KIC 8462852 · harmonic shape · time validation · source confusion