A fixed product relation gives relative errors of 0.987 to 1.075 for the known 3h signal of KIC 5520878 in Kepler Q11 to Q16

We test a constant complex product relation within the known h, 2h, 3h frequency family of the RR Lyrae star KIC 5520878. We fit local coefficients in public Kepler release 25 light curves. A constant fitted in quarters 2 to 10 predicts the 3h coefficient from the measured h and 2h coefficients in quarters 11 to 16. Relative root mean square errors range from 0.987 to 1.075 across two flux products, three window lengths, two primary harmonic counts, and flux or magnitude scales. A zero prediction has error one. The product relation gives no useful point gain over that reference. Quarter resampling gives broad error ranges. A cubic relation has smaller point errors but does not give a firm physical result. This is a null test of a fixed local relation, not a new signal or planet detection. Independent instrument data and pixel localization are absent.

Kepler · RR Lyrae · KIC 5520878 · combination frequency · null result