V.R373 — LIGO Echo Window: Δt = 4GM(1-ι_τ²)/(c³·ι_τ)

The echo separation Δt=4GM(ι_τ⁻¹-ι_τ)/c³=4GM(1-ι_τ²)/(c³·ι_τ). Computed values: M=10 M_☉: Δt=0.5101 ms; M=30 M_☉: Δt=1.5303 ms; M=62 M_☉: Δt=3.1626 ms; M=150 M_☉: Δt=7.6515 ms. All lie in the 0.5-8 ms post-merger window; current LIGO sensitivity reaches ~50-500 ms. Next-generation detectors (ET, CE) needed for direct detection. Falsifiable: absence of echoes at these precise times would challenge T² topology.