(26308) 1998 SM165 and S/2001 (26308) 1

compiled by Wm. Robert Johnston
last updated 11 October 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: 47.4109781076965 AU
orbital period P: 326.4574 y (=119241 d)
eccentricity e: 0.368467617927425
perihelion distance q: 29.9415679407442 AU
aphelion distance Q: 64.88038827 AU
inclination i: 13.5248864922825°
argument of perihelion omega: 130.505296058762°
ascending node OMEGA: 183.174348684175°
mean anomaly M: 33.5526525666883°
perihelion passage TP: 1974-08-27.7480978
Epoch: 30 JAN 2005
data arc: 1982-2002 (60 obs.)

orbital data, secondary:
semimajor axis a: 11,310 ± 110 km [M04b]
semimajor axis/primary radius a/Rp: (54?)
orbital period P: 130.1 ± 1 d [M04b]
eccentricity e: ?

other data, primary:
diameter: 287 ± 36 km [S06b]
absolute magnitude H: 5.8 [JPL]
rotation period: 8.40 ± 0.05 h [S06b]
amplitude delta M: ?
color index B-V: 0.966 ± 0.091 [H02a]
color index V-R: 0.687 ± 0.079 [H02a]
color index V-I: 1.29 ± 0.07 [B05c]
color index V-J: 2.37 ± 0.01 [B05c]
color index V-H: 2.88 ± 0.08 [B05c]
slope parameter G: (0.15) [a]
geometric albedo: 0.07 ± 0.02 [S06b]
mass (system): (6.78 ± 0.24)x1018 kg [M04b]
density: 0.52 +0.29/-0.14 g/cm3 [S06b]
BBFB type: RR [B05c]

other data, secondary:
diameter: 96 ± 12 km [S06b]
diameter ratio Ds/Dp: (0.33 ± 0.02) [M05b]
component magnitude difference: (2.4) [M05b]
rotation period: ?

--(26308) 1998 SM165--discovery and notes:

Primary discovered 16 September 1998 from Steward Observatory, Kitt Peak-Spacewatch, Arizona, USA, by N. Danzl. Linked to prediscovery observations from 1982.

Companion discovered 22 December 2001 by M. E. Brown and C. A. Trujillo in Hubble Space Telescope images; announced 24 January 2002.

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

--Links, more technical:

--Links, less technical:

--Links to ADS abstracts:


© 2003-2005, 2006 by Wm. Robert Johnston.
Last modified 11 October 2006.
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