Asteroids with Satellites Database--Johnston's Archive

(16974) Iphthime

compiled by Wm. Robert Johnston
last updated 27 May 2019

--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 ± 3.3 km [*D]
rotation period RPp: 78.9 ± 0.4 h [M11e]
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.

Named 2017 Dec 03 for the mythological sister of Penelope [MPC107739].

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

--Links, more technical:

--Links, less technical:

--Links to ADS abstracts:


© 2018, 2019 by Wm. Robert Johnston.
Last modified 27 May 2019.
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