Asteroids with Satellites Database--Johnston's Archive

(66391) 1999 KW4

compiled by Wm. Robert Johnston
last updated 20 September 2014

--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: NEA, Aten (PHA)


orbital data, primary (osculating elements) [JPL] :
semimajor axis a: 0.642291859 AU
orbital period P: 0.514762413 yr
(= 188.0169715 d)
eccentricity e: 0.688460238
perihelion distance q: 0.200099453 AU
aphelion distance Q: 1.084484265 AU
inclination i: 38.8871737°
argument of perihelion ω: 192.6154467°
ascending node Ω: 244.9231238°
mean anomaly M: 221.227725°
perihelion passage TP: 2014 Aug 03.47650
Epoch: 2014 May 23
data arc: 1998-2013 (1772 obs.)
Earth MOID: 0.0132776 AU
Jupiter Tisserand invariant TJ: 8.498


orbital data, secondary:
binary dynamical type:A [P07f]
semimajor axis as: 2.548 ± 0.015 km [O06a]
separation/primary radius as/rp:3.9 [*D]
separation/Hill radius as/rH:0.114 [*D]
orbital period Ps: 0.7259 ± 0.0015 d [O06a]
eccentricity es: 0.0004 ± 0.0019 [O06a]
inclination is:156.1° ± 2° [O06a]
ascending node Ωs:105.4° ± 3° [O06a]
argument of pericenter ωs:319.7° ± 182° [O06a]
pericenter passage TP:2001 May 26.41± 0.88 [O06a]
normalized ang. mom. αL: 1.06 [P07f]

other data, system (combined):
absolute mag. H: 16.5 [MPC]
16.38 [JPL]
slope parameter G: (0.15) [*A]
effective diameter dE: 1.39 km [*D]
geometric albedo: 0.23 [*E]
color index U-B: ?
color index B-V: ?
taxonomic type: S: (SMASSII) [JPL]
mass m: 2.49x1012 ± 5.4x1010 kg [O06a]
density ρ: 1.97 ± 0.24 g/cm3[O06a]
Hill radius rH: 22 km [*D]

other data, primary:
diameter dp: 1.317 ± 0.04 km [O06a]
dimensions :1.532 x 1.495 x 1.347 km [O06a]
rotation period RPp: 2.7645 ± 0.0003 h [O06a]
amplitude in mag., rotational ΔM: 0.13 [H03a]
pole direction Β, λ: ? , ?
densityρp:1.97± 0.24/O06a g/cm3 [O06a]


other data, secondary:
diameter ds: 0.451 ± 0.027 km [O06a]
dimensions :0.571 x 0.463 x 0.349km [O06a]
axial ratios a/b, b/c:1.23;1.33 [*D]
diameter ratio ds/dp: 0.341 ± 0.025 [*D]
component mag. difference ΔM: 2.5 [*D]
rotation period RPs: 17.4 ± 0.1 h [O06a]
densityρs:2.81± 0.82/0.63 g/cm3 [O06a]

-- (66391) 1999 KW4 --discovery and notes:

Primary discovered 1999 May 20 from Socorro, New Mexico, USA by LINEAR. Linked to prediscovery observations from 1998 May 29. Permanent number assigned 2003 Sep 10.

Companion discovered 2001 May 21 using radar and lightcurve observations. Announced 2001 May 23.

--Links, more technical:

--Links, less technical:

--Links to ADS abstracts:


© 2001-2007, 2014 by Wm. Robert Johnston.
Last modified 20 September 2014.
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