Ecliptic Longitude of Solution B: A Kuiper-Cliff Longitude Sweep with ATMAN v5.0 (Paper V)

(Abstract) We present a full 360° ecliptic longitude sweep for Solution B (6 M⊕, a=75 au, i=10°), the preferred trans-Neptunian perturberidentified in Papers III–IV of this series. Using the ATMAN v5. 0N-body suite and the CKBO metric, a coarse pass (Δλ=10°) followedby a fine pass (Δλ=2°, 242°–278°) yields a best-fit eclipticlongitude λSolB = 260° ± 4° (J2000: RA 17h 13m, Dec −31°;Ophiuchus/Scorpius border). The depletion proxy at the best-fitposition is 78. 9% — the highest value recorded for Solution Bacross this series. The angular separation from Erebo (λErebo=156°, Paper II) is Δλ=104°, placing both hypotheticalperturbers near orbital quadrature. The predicted sky positionis accessible to Rubin/LSST in a single exposure (V≈19–21 mag). This is Paper V of the ATMAN v5. 0 series. Author: Ariel Fernando Martini, Buenos Aires, Argentina (2026). Contact: arielₘartini₃@hotmail. com