Asteroids with Satellites Database--Johnston's Archive

(42355) Typhon and Echidna

compiled by Wm. Robert Johnston
last updated 24 May 2014
under construction--testing upgrades!

--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: ?
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 ± 7/7 km [S12a]
color index V-I:0.99± 0.04 [G08a]
rotation period RPp: 9.67 h [D09b]
amplitude in mag., rotational ΔM: ?
pole direction : ? ; ?


other data, secondary:
diameter ds: 89 ± 6/6 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 HST observations from Hubble Space Telescope. Announced 2006 Feb 15 [I8689]. 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 24 May 2014.
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