Asteroids with Satellites Database--Johnston's Archive

(16974) Iphthime

compiled by Wm. Robert Johnston
last updated 12 April 2018

--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: Jupiter trojan asteroid, L4


orbital data, primary (osculating elements) [JPL] :
semimajor axis a: 5.19017267 AU
orbital period P: 11.82422567 yr
(= 4318.879999 d)
eccentricity e: 0.070401721
perihelion distance q: 4.82477558 AU
aphelion distance Q: 5.55556977 AU
inclination i: 15.036372°
argument of perihelion ω: 134.715771°
ascending node Ω: 241.559536°
mean anomaly M: 261.735542°
perihelion passage TP: 2021 Jun 13.86778
Epoch: 2018 Mar 23
data arc: 1974-2017 (1073 obs.)
Earth MOID: 3.8459 AU
Jupiter Tisserand invariant TJ: 2.927


orbital data, secondary:
semimajor axis as: 179 ± 10 km [*D]
separation/primary radius as/rp:7.9 [*D]
separation/Hill radius as/rH:0.0093 [*E]
orbital period Ps: 3.29 d [*A]
eccentricity es: ?
normalized ang. mom. αL: ?

other data, system (combined):
absolute mag. H: 9.8 [MPC]
slope parameter G: (0.15) [*A]
effective diameter dE: 57.34 ± 0.33 km [*M]
geometric albedo: 0.065 ± 0.01 [*M]
color index U-B: ?
color index B-V: ?
taxonomic type: ?
mass m: ?
density ρ: (1.6 g/cm3) [*A]
Hill radius rH: 19000 km [*E]

other data, primary:
diameter dp: 45.5 ± 3.29 km [*D]
rotation period RPp: 78.9 ± 0.4 h [*LC]
amplitude in mag., rotational ΔM: ?
pole direction Β, λ: ? , ?


other data, secondary:
diameter ds: 34.9 ± 5.44 km [*D]
diameter ratio ds/dp: 0.767 ± 0.119 [*D]
component mag. difference ΔM: 0.6 ± 0.3 [*D]
rotation period RPs: ?

-- (16974) Iphthime --discovery and notes:

Primary discovered 1998 Nov 18 from Socorro, New Mexico, USA by LINEAR Program. Alternate designation(s): 1998 WR21, 1974 WX, 1986 WS. Linked to prediscovery observations from 1974 Nov 18. Permanent number assigned 2000 Sep 13.

Companion discovered 2013 Mar 13 using Hubble Space Telescope observations. Announced 2016 Mar.

--Links, more technical:

--Links, less technical:

--Links to ADS abstracts:


© 2018 by Wm. Robert Johnston.
Last modified 12 April 2018.
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