LC light-curve FT amplitude spectra of KIC 10001893 (var) and bright neighbor (cmp) stars shown within the low-frequency region. Panel a: FT of var aperture reduced data (4σ = 20 ppm), (b) var PSF (4σ = 21 ppm), (c) var/cmpaperture (4σ = 22 ppm), (d) var/cmp PSF (4σ = 23 ppm), (e) cmp aperture (4σ = 9.2 ppm), and (f) cmpPSF (4σ = 14.0 ppm). Green lines indicate the 4σ signal detection thresholds. Vertical short bars in panels a–d denote places where k₁ = 52.683 μHz, k₂ = 35.578 μHz, and k₃ = 14.261 μHz, frequencies were found by Silvotti et al. (2014).