(65803) Didymos

compiled by Wm. Robert Johnston
last updated 30 December 2005

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: 1.64434448313588 AU
orbital period P: 2.1086 y (=770.2 d)
eccentricity e: 0.384010096577476
perihelion distance q: 1.01289959936023 AU
aphelion distance Q: 2.27578937 AU
inclination i: 3.4081768123334°
argument of perihelion omega: 319.183571458625°
ascending node OMEGA: 73.2588261043845°
mean anomaly M: 214.284432963256°
perihelion passage TP: 2005-12-07.7389621
Epoch: 30 JAN 2005
data arc: 1996-2004 (706 obs.)

orbital data, secondary:
semimajor axis a: (1.1 km)
semimajor axis/primary radius a/Rp: 2.8 ± 0.2 [P05a]
orbital period P: 11.900 ± 0.005 h [P05a]
eccentricity e: 0.06 +0.06/-0.04 [P05a]

other data, primary:
diameter: 800 m [I8244]
absolute magnitude H: 17.70 ± 0.03 [K04a]
rotation period: 2.260 ± 0.001 h [OOd]
amplitude delta M: 0.10 [OOd]
color index U-B: 0.211 ± 0.032 [K04a]
color index B-V: 0.795 ± 0.016 [K04a]
color index V-R: 0.458 ± 0.009 [K04a]
color index V-I: 0.820 ± 0.009 [K04a]
slope parameter G: 0.20 ± 0.02 [K04a]
geometric albedo: 0.147 [K04a]
mass: ?
density: (1.7 ± 0.4) g/cm3 [P05a]
type: X [K04a]

other data, secondary:
diameter: 150 ± 50 m [I8244]
diameter ratio Ds/Dp: 0.22 ± 0.02 [P05a]
component magnitude difference: ?
rotation period: ?

--(65803) Didymos--discovery and notes:

Primary discovered 11 April 1996 by J. Montani and J. V. Scotti of the Spacewatch program, Kitt Peak, Arizona, USA. Alternate designation 1996 GT.

Companion discovered by Petr Pravec, Peter Kusnirak, Lenka Sarounova, Marek Wolf, Don Pray, Brian Warner, Al Grauer, Steve Larson, L. A. M. Benner, M. C. Nolan, J. D. Giorgini, R. F. Jurgens, S. J. Ostro, J.-L. Margot, and C. Magri: revealed by lightcurve observations made 20-24 November 2003 from Ondrejov Observatory, Steward Observatory, and Rhode Island; confirmed by radar observations made 23-24 November 2003 from Arecibo Observatory, Puerto Rico.

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

--Links, more technical:

--Links, less technical:

--Links to ADS abstracts:


© 2003-2004, 2005 by Wm. Robert Johnston.
Last modified 30 December 2005.
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