Sample of () identified in χ-image analysis of individual H1- and L1-spectrograms (top-left panels), representing two elements from a total of nm = 320 H1- and L1-spectrograms (lower panels). Peak values indicated (white rectangles) have (H1) and (L1). Over the snippet of T = 2048 s of H1L1-data, time differences and identified by local maxima of over the 64 segments of 32 s and 320 trials of H1- and L1-spectrograms are, as expected, uncorrelated, evidenced by a correlation coefficient ρ_{[ts], [τs]} = 1.29 × 10⁻⁴. (Right-top-panels) PDF₁(t_s) and PDF₂(t_s) of H1 and, respectively, L1 are centered around t_s − t_m = (0.92±0.09) s and τ_s = (3.00±0.09) s. Binning over δt_res = 0.025 s, cross-correlation of the two PDFs (over each segment covering H1L1-data over T = 2048 s) shows a global maximum in segment 58 containing GW170817 consistent with zero time difference within δt_res = 0.025 s.