V.D243 — T² GW Echo Time Formulas with Frequency Bands

GW echo time formulas with frequency bands: t₊=4GM·ι_τ/c³ (inner), t₋=4GM·ι_τ⁻¹/c³ (outer), ratio t₋/t₊=ι_τ⁻²=8.585. For GW150914 (62 M_☉): t₊=0.417 ms (f≈2399 Hz), t₋=3.580 ms (f≈279 Hz), both in LIGO band. For Sgr A*: echoes at ~37 mHz and ~4.3 mHz in LISA band.