Irregular moons of Saturn -- Greip

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

23 Oct 2018 / TD


	Overview Table
Moon name	Greip
Saturn range	18e6	km
Orbit period	2.6	years
Orbit direction	retrograde
Size ~	5	km
Rotation period	12	45	hh:mm
Discovery year	2006

(A)	Designations and discovery circumstances
(A1)	Moon name	Greip
(A2)	Moon abbrev. (TD)	Gre
(A3)	IAU number	Saturn LI
(A4)	Provisional designation	S/2006 S 4
(A5)	SPICE ID	651
(A6)	Also-used label	S51
(A7)	First observation date	05 Jan 2006
(A7)	Announcement date	30 Jun 2006
(A7)	IAU circular announcement no.	8727
(A8)	Discoverers	Sheppard S. et al.

(B)	Orbit parameters
(B1)	Orbit direction	retrograde
(B2)	Group member	Norse
(B3)	Dynamical family	Hyrrokkin/Greip? Suttungr? 
(B4)	Periapsis range	12.65e6	km
(B5)	Semi-major axis	18.46e6	km
(B6)	Apoapsis range	24.27e6	km
(B7)	Semi-major axis	306	R_Saturn
(B8)	Semi-major axis	0.123	au
(B9)	Semi-major axis	0.28	R_Hill
(B10)	Orbit eccentricity	0.32	
(B11)	Orbit inclination	174.8	°
(B12)	Inclination supplemental angle	5.2	°
(B13)	Orbital period	936	d
(B14)	Orbital period	2	6	3.25	y:m:w
(B15)	Mean orbit velocity	1.43	km/s

(C)	Physical parameters
(C1)	Mean size ~	5	-0.75	+1.25	km
(C2)	Mean radius ~	2.3	km
(C3)	Equatorial circumference ~	15	km
(C4)	Minimum equatorial axes ratio	1.18
(C5)	Axes radii (a x b x c) ~	unknown
(C5)	
(C6)	Mass ~	3e13	kg
(C7)	Mean density (?)	0.5	g/cm^3
(C8)	Surface escape velocity ~	3	km/h
(C9)	Rotation period	12.75	h
(C9)	Rotation period error	0.35	h
(C9)	Spin rate	1.88	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 ~	15.4	mag
(C15)	Apparent visual magnitude from Earth	24.4	mag
(C16)	Best apparent magnitude for Cassini	15.4	mag
(C17)	Spectral slope	unknown
(C17)	B-R color index	unknown
(C18)	Albedo (?)	0.06	
(C19)	Hill sphere radius ~	310	km
(C20)	Hill sphere radius ~	135	r_Gre