Asteroids with Satellites Database--Johnston's Archive

(42355) Typhon and Echidna

compiled by Wm. Robert Johnston
last updated 21 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: Centaur


orbital data, primary (osculating elements) [JPL] :
semimajor axis a: 38.1075 AU
orbital period P: 235.2471 yr
(= 85924.0 d)
eccentricity e: 0.540154
perihelion distance q: 17.523591 AU
aphelion distance Q: 58.6915 AU
inclination i: 2.425476°
argument of perihelion ω: 159.03926°
ascending node Ω: 351.91281°
mean anomaly M: 12.26421°
perihelion passage TP: 2006 May 17.80
Epoch: 2014 May 23
data arc: 1989-2013 (172 obs.)
Earth MOID: 16.535 AU
Jupiter Tisserand invariant TJ: 4.687
Neptune Tisserand invariant TN:2.68 [*D]


orbital data, secondary:
semimajor axis as: 1628 ± 29 km [G08a]
separation/primary radius as/rp:20 [*D]
separation/Hill radius as/rH:0.011 [*D]
orbital period Ps: 18.9709 ± 0.0064 d [G08a]
eccentricity es: 0.526 ± 0.015 [G08a]
inclination is:37.9° ± 2° [G08a]
ascending node Ωs:253.1° ± 4° [G08a]
argument of pericenter ωs:352.1° ± 1.4° [G08a]
mean anomaly M:11.5° ± 1.6° [G08a]
normalized ang. mom. αL: ?

other data, system (combined):
absolute mag. H: 7.5 [MPC]
7.72 ± 0.04 [S12a]
slope parameter G: (0.15) [*A]
effective diameter dE: 185 ± 7/7 km [S12a]
geometric albedo: 0.044 ± 0.003/0.003 [S12a]
color index U-B: 0.21 [J07a]
color index B-V: 0.74 [T03b]
color index V-R:0.52 ± 0.01 [T03b]
color index B-R:1.26 [T03b]
color index V-I:0.99 ± 0.04 [G08a]
color index R-J:1.31 [*D]
color index V-J:1.83 ± 0.09 [D07c]
color index J-H:0.18 [*D]
color index V-H:2.01 ± 0.05 [D09c]
taxonomic type: BR,BB (G-mode) [P10a]
mass m: 9.49x1017 ± 5.2x1016 kg [G08a]
density ρ: 0.36 ± 0.08/0.07 g/cm3[S12a]
Hill radius rH: 140000 km [*D]

other data, primary:
diameter dp: 162 ± 7 km [S12a]
color index V-I:0.99 ± 0.04 [G08a]
rotation period RPp: 9.67 h [D09b]
amplitude in mag., rotational ΔM: 0.07 ± 0.01 [T10a]
pole direction Β, λ: ? , ?


other data, secondary:
diameter ds: 89 ± 6 km [S12a]
diameter ratio ds/dp: 0.55 ± 0.015 [S12a]
component mag. difference ΔM: 1.30 ± 0.06 [G08a]
color index V-I:0.95± 0.04 [G08a]
rotation period RPs: ?

-- (42355) Typhon and Echidna --discovery and notes:

Primary discovered 2002 Feb 05 from Palomar Observatory, California, USA by NEAT. Alternate designation(s): 2002 CR46 . Linked to prediscovery observations from 1989 Dec 28. Permanent number assigned 2002 May 26.

Named 2006 Nov 09 for the Greek mythological monster [MPC57951].

Companion discovered 2006 Jan 20 by K. S. Noll, W. M. Grundy, D. C. Stephens, and H. F. Levison using Hubble Space Telescope observations from Hubble Space Telescope. Announced 2006 Feb 15 [N06c]. Permanent designation I Echidna, assigned 2006 Nov 09; named for the Greek mythological monster [MPC57951].

--Links, more technical:

--Links, less technical:

--Links to ADS abstracts:


© 2006-2012, 2014 by Wm. Robert Johnston.
Last modified 21 September 2014.
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