(40724) 1999 SY8

--Orbital and physical data--

(See this page for definitions of quantities; source codes in brackets, see this link for full references; *A, *D, and *E indicate assumed, derived, and estimated values, respectively.)

dynamical type, primary: main belt asteroid orbital data, primary (osculating elements) [JPL] : semimajor axis a: 2.55794945677 AU orbital period P: 4.0911569484 yr (= 1494.2950754 d) eccentricity e: 0.10387442471 perihelion distance q: 2.2922439285 AU aphelion distance Q: 2.82365498503 AU inclination i: 13.563504972° argument of perihelion ω: 136.71403656° ascending node Ω: 5.36013766° mean anomaly M: 343.81859221° perihelion passage TP: 2026 Jan 27.1661055 Epoch: 2025 Nov 21 data arc: 1991-2026 (4002 obs.) Earth MOID: 1.31922 AU Jupiter Tisserand invariant TJ: 3.39 orbital data, secondary: semimajor axis as: 8.4 km (separation) [W26a] separation/primary radius as/rp: 3.8 [*E] separation/Hill radius as/rH: 0.011 [*E] orbital period Ps: 0.325 ± 0.022 d [W26a] eccentricity es: ? normalized ang. mom. αL: ?

other data, system (combined): absolute mag. H: 13.71 [MPC] slope parameter G: (0.15) [*A] effective diameter dE: 5.39 ± 0.05 km [M19a] geometric albedo: 0.328 ± 0.037 [M19a] color index U-B: ? color index B-V: ? color index J-H: 1.55 ± 1.15 [S10b] taxonomic type: ? mass m: ? density ρ: (1.6 g/cm3) [*A] Hill radius rH: 800 km [*E] other data, primary: diameter dp: 4.4 km [*D] dimensions : 4.9 x 3.9 km [W26a] axial ratios a/b, b/c: 1.26, ? [*D] rotation period RPp: ? amplitude in mag., rotational ΔM: ? pole direction Β, λ: ? , ? other data, secondary: diameter ds: 1.8 ± 1.1 km [*D] axial ratios a/b, b/c: 1.4; ? [*D] diameter ratio ds/dp: 0.41 [*D] component mag. difference ΔM: 1.96 [*D] rotation period RPs: ?