(617) Patroclus and Menoetius

compiled by Wm. Robert Johnston
last updated 7 February 2006

Orbital elements and other data (Assumed or derived values in parenthesis, my estimates in italics and parenthesis. Source identifications in brackets, see this link for sources):

orbital data, primary (osculating elements) [JPL]:
semimajor axis a: 5.2275878 AU
orbital period P: 11.9525 y (=4365.7 d)
eccentricity e: 0.138108
perihelion distance q: 4.5056161 AU
aphelion distance Q: 5.9495595 AU
inclination i: 22.03416°
argument of perihelion omega: 307.8081°
ascending node OMEGA: 44.36745°
mean anomaly M: 149.93555°
perihelion passage TP: 2000-08-25.7544056
Epoch: 18 AUG 2005
data arc: 1906-1999 (130 obs.)

orbital data, secondary:
semimajor axis a: 680 ± 20 km [M06a]
semimajor axis/primary radius a/Rp: (11.2)
orbital period P: 4.283 ± 0.004 d [M06a]
eccentricity e: 0.02 ± 0.02 [M06a]
orbit pole solution: L=234° ± 5°
B=-62° ± 1° (ECJ2000)

other data, primary:
diameter: 121.8 ± 3.2 km [M06a]
absolute magnitude H: 8.19 [JPL]
rotation period: >40 h [MPb]
amplitude delta M: >0.1 [MPb]
color index U-B: 0.215 ± 0.045 [SBa]
color index B-V: 0.677 ± 0.013 [SBa]
color index V-R: ?
color index R-I: ?
slope parameter G: (0.15) [a]
geometric albedo: 0.047 ± 0.003 [IR]
mass (system): (1.36 ± 0.11)x1018 kg [M06a]
density: (0.8 +0.2/-0.1) g/cm3 [M06a]
type: P [SBd]

other data, secondary:
diameter: 112.6 ± 3.2 km [M06a]
diameter ratio Ds/Dp: (0.92)
component magnitude difference: (0.17)
rotation period: ?

--(617) Patroclus--discovery and notes:

Primary discovered 17 October 1906 by A. Kopff from Heidelberg, Germany. Alternate designations 1906 VY, 1941 XC, and 1962 NB.

Companion discovered 22 September 2001 by William J. Merline, Laird M. Close, N. Siegler, D. Potter, C. R. Chapman, C. Dumas, F. Menard, and D. C. Slater using the Gemini North adaptive optics telescope at Mauna Kea, Hawaii; announced 29 October 2001. Designated S/2001 (617) 1, in February 2006 named Menoetius.

Patroclus was the second Trojan asteroid to be discovered. It orbits in Jupiter's L5 position (60° behind Jupiter).

See more information and links at Asteroid/Comet Connection Catchall Catalog page

--Links, more technical:

--Links, less technical:

--Links to ADS abstracts:


© 2001-2005, 2006 by Wm. Robert Johnston.
Last modified 7 February 2006.
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