Irregular moons of Saturn -- Bestla

For notes, see https://tilmanndenk.de/outersaturnianmoons/bestla/#1

23 Oct 2018 / TD


	Overview Table
Moon name	Bestla
Saturn range	20e6	km
Orbit period	3.0	years
Orbit direction	retrograde
Size ~	7	km
Rotation period	14	37	hh:mm
Discovery year	2004

(A)	Designations and discovery circumstances
(A1)	Moon name	Bestla
(A2)	Moon abbrev. (TD)	Bes
(A3)	IAU number	Saturn XXXIX
(A4)	Provisional designation	S/2004 S 18
(A5)	SPICE ID	639
(A6)	Also-used label	S39
(A7)	First observation date	13 Dec 2004
(A7)	Announcement date	04 May 2005
(A7)	IAU circular announcement no.	8523
(A8)	Discoverers	Jewitt, et al.

(B)	Orbit parameters
(B1)	Orbit direction	retrograde
(B2)	Group member	Norse
(B3)	Dynamical family	Bestla/Narvi
(B4)	Periapsis range	9.68e6	km
(B5)	Semi-major axis	20.21e6	km
(B6)	Apoapsis range	30.74e6	km
(B7)	Semi-major axis	335	R_Saturn
(B8)	Semi-major axis	0.135	au
(B9)	Semi-major axis	0.31	R_Hill
(B10)	Orbit eccentricity	0.52	
(B11)	Orbit inclination	145.2	°
(B12)	Inclination supplemental angle	34.8	°
(B13)	Orbital period	1087	d
(B14)	Orbital period	2	11	3.25	y:m:w
(B15)	Mean orbit velocity	1.37	km/s

(C)	Physical parameters
(C1)	Mean size ~	7	-1.25	+2	km
(C2)	Mean radius ~	3.3	km
(C3)	Equatorial circumference ~	20	km
(C4)	Minimum equatorial axes ratio	1.47
(C5)	Axes radii (a x b x c) ~	unknown
(C5)	
(C6)	Mass ~	8e13	kg
(C7)	Mean density (?)	0.5	g/cm^3
(C8)	Surface escape velocity ~	4	km/h
(C9)	Rotation period (sidereal)	14.6238	h
(C9)	Rotation period error	0.0001	h
(C9)	Spin rate	1.64116	d^(-1)
(C10)	Spin direction	unknown
(C11)	Seasons	unknown
(C12)	Pole direction (ecliptic longitude λ)	unknown
(C12)	Pole direction (ecliptic latitude β)	unknown
(C13)	Pole direction (geocentric RA)	unknown
(C13)	Pole direction (geocentric Dec)	unknown
(C14)	Absolute visual magnitude ~	14.6	mag
(C15)	Apparent visual magnitude from Earth	23.8	mag
(C16)	Best apparent magnitude for Cassini	13.5	mag
(C17)	Spectral slope		
(C17)	B-R color index ~	1.32	
(C18)	Albedo (?)	0.06	
(C19)	Hill sphere radius ~	340	km
(C20)	Hill sphere radius ~	100	r_Bes