A nine-pixel aperture reduces the KIC 8164262 amplitude contrast in Kepler Q4, Q5, Q8, and Q9

We test whether the measured seasonal amplitude contrast of the known KIC 8164262 oscillation depends on pixel aperture. In four Kepler release 25 quarters, the contrast falls from 29.74 to 17.38 ppm when the pipeline aperture is replaced by the nine brightest pixels. The paired reduction is 12.37 ppm with a conditional standard error of 1.95 ppm. The reduction ranges from 11.21 to 13.21 ppm across nine orbital-mask and baseline choices. Pipeline pixel sums reproduce archived aperture flux within 0.241 ppm. The result shows an aperture contribution to the measured contrast. It does not separate contamination, background bias, motion, or detector response. Only two returns to each of two detector orientations are tested. There is no independent-observatory confirmation and no new planet or stellar-mode claim. Code, checked source hashes, fit tables, figures, and selected pixel samples support reproduction.

Kepler · tidal oscillation · aperture photometry · instrument artifacts · KIC 8164262