Asteroids with Satellites Database--Johnston's Archive

(399307) 1991 RJ2

compiled by Wm. Robert Johnston
last updated 17 January 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, Amor


orbital data, primary (osculating elements) [JPL] :
semimajor axis a: 2.2083582416 AU
orbital period P: 3.281740899 yr
(= 1198.6785019 d)
eccentricity e: 0.428903368
perihelion distance q: 1.26118595 AU
aphelion distance Q: 3.1555305285 AU
inclination i: 8.9433021°
argument of perihelion ω: 150.817669°
ascending node Ω: 171.820039°
mean anomaly M: 37.125057°
perihelion passage TP: 2014 Aug 07.386090
Epoch: 2014 Dec 09
data arc: 1991-2014 (206 obs.)
Earth MOID: 0.262188 AU
Jupiter Tisserand invariant TJ: 3.519


orbital data, secondary:
semimajor axis as: 0.86 km [*E]
separation/primary radius as/rp:3.4 [*E]
separation/Hill radius as/rH:0.017 [*E]
orbital period Ps: 0.66321 ± 0.00004 d [W15b]
eccentricity es: ?
normalized ang. mom. αL: ?

other data, system (combined):
absolute mag. H: 18.9 [MPC]
slope parameter G: (0.15) [*A]
effective diameter dE: 0.55 km [*E]
geometric albedo: (0.16 ) [*A]
color index U-B: ?
color index B-V: ?
taxonomic type: ?
mass m: ?
density ρ: (1.6 g/cm3) [*A]
Hill radius rH: 51 km [*E]

other data, primary:
diameter dp: 0.5 km [*E]
rotation period RPp: 3.4907 ± 0.0002 h [W15b]
amplitude in mag., rotational ΔM: 0.09 [W15b]
amplitude in mag., mutual events ΔM:0.35 [W15b]
pole direction Β, λ: ? , ?


other data, secondary:
diameter ds: 0.24 km [*E]
axial ratios a/b, b/c:1.07;? [W15b]
diameter ratio ds/dp: >0.47 ± 0.02 [W15b]
component mag. difference ΔM: <1.64 [*D]
rotation period RPs: 15.917 ± 0.001 h [W15b]

-- (399307) 1991 RJ2 --discovery and notes:

Primary discovered 1991 Sep 08 from Palomar Observatory, California, USA by E. F. Helin. Permanent number assigned 2014 Jul 12.

Companion discovered 2014 Aug 27 by B. D. Warner, J. T. Pollock, D. E. Reichart, J. B. Haislip, A. P. LaCluyze, A. Verveer, T. Spuck, A. W. Harris using lightcurve observations from Palmer Divide Observatory, Colorado Springs, Colorado, USA; PROMPT Telescope, Chile; Perth Observatory, Australia. Announced 2014 Dec [W15b].

--Links, more technical:

--Links, less technical:

--Links to ADS abstracts:


© 2015, 2014 by Wm. Robert Johnston.
Last modified 17 January 2015.
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