Irregular moons of Saturn -- Siarnaq For notes, see https://tilmanndenk.de/outersaturnianmoons/siarnaq/#1 22 Oct 2018 / TD Overview Table Moon name Siarnaq Saturn range 18e6 km Orbit period 2.5 years Orbit direction prograde Size ~ 39 km Rotation period 10 11 hh:mm Discovery year 2000 (A) Designations and discovery circumstances (A1) Moon name Siarnaq (A2) Moon abbrev. (TD) Sia (A3) IAU number Saturn XXIX (A4) Provisional designation S/2000 S 3 (A5) SPICE ID 629 (A6) Also-used label S29 (A7) First observation date 23 Sep 2000 (A7) Announcement date 25 Oct 2000 (A7) IAU circular announcement no. 7513 (A8) Discoverers Gladman, Kavelaars, et al. (B) Orbit parameters (B1) Orbit direction prograde (B2) Group member Inuit (B3) Dynamical family Siarnaq (B4) Periapsis range 13.09e6 km (B5) Semi-major axis 18.18e6 km (B6) Apoapsis range 23.27e6 km (B7) Semi-major axis 301 R_Saturn (B8) Semi-major axis 0.122 au (B9) Semi-major axis 0.28 R_Hill (B10) Orbit eccentricity 0.28 (B11) Orbit inclination 45.8 ° (B12) Inclination supplemental angle 45.8 ° (B13) Orbital period 896 d (B14) Orbital period 2 5 2 y:m:w (B15) Mean orbit velocity 1.44 km/s (C) Physical parameters (C1) Mean size ~ 39 -6 +6 km (C2) Mean radius ~ 19.7 km (C3) Equatorial circumference ~ 130 km (C4) Minimum equatorial axes ratio 1.17 (C5) Axes radii (a x b x c) ~ (C5) (C6) Mass ~ 1.6e16 kg (C7) Mean density (?) 0.5 g/cm^3 (C8) Surface escape velocity ~ 26 km/h (C9) Rotation period (sidereal) 10.18785 h (C9) Rotation period error 0.00005 h (C9) Spin rate 2.35575 d^(-1) (C10) Spin direction lying on the side (C11) Seasons extreme (C12) Pole direction (ecliptic longitude λ) 98 ±15 (C12) Pole direction (ecliptic latitude β) -23 ±15 (C13) Pole direction (geocentric RA) 97 ±15 (C13) Pole direction (geocentric Dec) 0 ±15 (C14) Absolute visual magnitude ~ 10.6 mag (C15) Apparent visual magnitude from Earth 20.1 mag (C16) Best apparent magnitude for Cassini 10.8 mag (C17) Spectral slope ~ +13.0 %/100nm (C17) B-R color index ~ 1.36 (C18) Albedo (?) 0.06 (C19) Hill sphere radius ~ 2900 km (C20) Hill sphere radius ~ 140 r_Sia