(65489) Ceto and Phorcys

compiled by Wm. Robert Johnston
last updated 25 November 2008

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: 102.626094 AU
orbital period P: 1,039.67 y (= 379,743 d)
eccentricity e: 0.8258985
perihelion distance q: 17.8673569 AU
aphelion distance Q: 187.3848311 AU
inclination i: 22.27585°
argument of perihelion omega: 320.07855°
ascending node OMEGA: 171.94272°
mean anomaly M: 5.92497°
perihelion passage TP: 1989-08-12.163
Epoch: 22 SEP 2006
data arc: 1987-2003 (43 obs.)

orbital data, secondary:
semimajor axis a: 1,841±48 km [G06a]
semimajor axis/primary radius a/Rp: (21.4±2.8)
orbital period P: 9.554±0.011 d [G06a]
eccentricity e: <0.015 [G06a]
inclination i: 68.8°±2.9° or 116.6°±2.9°
to J2000 eq. [G06a]

other data, primary:
diameter: 172 ± 18 km [G06a]
a/b: 1.13 ± 0.02 [D08a]
absolute magnitude H: 6.613 ± 0.036 [G06a]
rotation period: 4.43 ± 0.03 h [D08a]
amplitude delta M: 0.13 ± 0.02 [D08a]
color index B-R: 1.42±0.04 [T03b]
color index B-V: 0.86±0.03 [T03b]
color index V-R: 0.56±0.03 [T03b]
color index R-I: ?
slope parameter G: (0.15) assumed
geometric albedo: 0.084 +0.021/-0.014 [G06a]
mass: (5.42±0.42)x1018 kg [G06a]
density: 1.38 +0.65/-0.32 g/cm3 [G06a]
type: ?

other data, secondary:
diameter: 134 ± 14 km [G06a]
diameter ratio Ds/Dp: (0.773±0.010)
component magnitude difference: 0.56 ± 0.03 [G06a]
rotation period: ?

--(65489) Ceto--discovery and notes:

Primary discovered 22 March 2003 from Palomar Observatory, California, USA, by the NEAT program. Linked to prediscovery observations from 1987. Preliminary designation 2003 FX128, name assigned 9 November 2006.

Companion discovered 11 April 2006 by K. S. Noll, H. F. Levison, W. M. Grundy, and D. S. Stephens with Hubble Space Telescope observations, reported August 2006. Named Phorcys in November 2006

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

--Links, more technical:

--Links, less technical:

--Links to ADS abstracts:


© 2006-2007, 2008 by Wm. Robert Johnston.
Last modified 25 November 2008.
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