A Constrained Search Region for Planet Nine from Trans-Neptunian Object Orbital Clustering

We report a constrained prediction for the sky position and heliocentric distance of the hypothetical Planet Nine, derived from orbital clustering analysis of 15 extreme trans-Neptunian objects (eTNOs). The best-fit position lies in the constellation Libra at ecliptic coordinates (λ, β) = (220.3°, −1.1°), equivalent to (α, δ) ≈ (14h 41m, −1° 06'), at a heliocentric distance of 205.6 ± 50 AU and an estimated mass of 13.9 ± 5 M⊕. The implied search area of ~25 deg² represents a 99.5% reduction relative to the canonical 4,800 deg² region of Batygin & Brown (2016). Standard multi-epoch imaging with any 8m-class telescope targeting slow-moving objects at V ~ 22–25 in this region is sufficient for optical confirmation. This prediction was formally recorded on 2026 February 6 at 08:05:37 UTC−3, prior to any observational confirmation.