Asteroids with Satellites Database--Johnston's Archive

(450894) 2008 BT18

compiled by Wm. Robert Johnston
last updated 28 November 2015

--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: NEA, Apollo (PHA)


orbital data, primary (osculating elements) [JPL] :
semimajor axis a: 2.222999067 AU
orbital period P: 3.314493129 yr
(= 1210.618615 d)
eccentricity e: 0.593195991
perihelion distance q: 0.904324933 AU
aphelion distance Q: 3.541673202 AU
inclination i: 8.1317743°
argument of perihelion ω: 139.247696°
ascending node Ω: 107.690055°
mean anomaly M: 287.475271°
perihelion passage TP: 2015 Jan 21.88829
Epoch: 2014 May 23
data arc: 1955-2008 (253 obs.)
Earth MOID: 0.0104424 AU
Jupiter Tisserand invariant TJ: 3.383


orbital data, secondary:
semimajor axis as: 1.5 km (separation) [B08c]
separation/primary radius as/rp:5.0 [*E]
separation/Hill radius as/rH:0.035 [*E]
orbital period Ps: 1.2 d [*E]
eccentricity es: ?
normalized ang. mom. αL: ?

other data, system (combined):
absolute mag. H: 18.3 [MPC]
18.2 ± 0.2 [B09a]
slope parameter G: 0.20 [B09a]
effective diameter dE: 0.63 km [*D]
geometric albedo: 0.21 [*E]
color index U-B: ?
color index B-V: ?
taxonomic type: ?
mass m: ?
density ρ: (1.6 g/cm3) [*A]
Hill radius rH: 43 km [*E]

other data, primary:
diameter dp: 0.6 km [B08c]
rotation period RPp: 2.726 ± 0.007 h [B09a]
amplitude in mag., rotational ΔM: 0.045 ± 0.002 [B09a]
pole direction Β, λ: ? , ?


other data, secondary:
diameter ds: >0.2 km [B08c]
diameter ratio ds/dp: 0.333 [*D]
component mag. difference ΔM: 2.4 [* D]
rotation period RPs: ?

-- 2008 BT18 --discovery and notes:

Primary discovered 2008 Jan 31 from Lincoln Laboratory ETS, New Mexico, USA by LINEAR. Linked to prediscovery observations from 1955 Mar 14.

Companion discovered 2008 Jul 06 by L. A. M. Benner, M. C. Nolan, E. S. Howell, C. Magri, J. D. Giorgini, S. J. Ostro, M. Brozovic, M. W. Busch, J. L. Margot, P. A. Taylor, M. K. Shepard, L. M. Carter, and T. M. Becker using radar observations from Arecibo Observatory, Puerto Rico. Announced 2008 Jul 29 [B08c].

--Links, more technical:

--Links, less technical:

--Links to ADS abstracts:


© 2008-2014, 2015 by Wm. Robert Johnston.
Last modified 28 November 2015.
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