Asteroids with Satellites Database--Johnston's Archive

(6311) Porubcan

compiled by Wm. Robert Johnston
last updated 28 February 2026

--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: main belt asteroid

orbital data, primary (osculating elements) [JPL] :
semimajor axis a: 2.28954920977 AU
orbital period P: 3.4644410491 yr
(= 1265.3870932 d)
eccentricity e: 0.22497524265
perihelion distance q: 1.7744573207 AU
aphelion distance Q: 2.8046410988 AU
inclination i: 5.168098679°
argument of perihelion ω: 70.24953112°
ascending node Ω: 344.03298985°
mean anomaly M: 19.49136295°
perihelion passage TP: 2025 Sep 13.48855804
Epoch: 2025 Nov 21
data arc: 1950-2025 (3476 obs.)
Earth MOID: 0.79298 AU
Jupiter Tisserand invariant TJ: 3.56

orbital data, secondary:
semimajor axis as: 11 km [*E]
separation/primary radius as/rp:4.0 [*E]
separation/Hill radius as/rH:0.015 [*E]
orbital period Ps: 0.8796 ± 0.0004 d [D26a]
eccentricity es: ?
normalized ang. mom. αL: ?

other data, system (combined):
absolute mag. H: 13.97 [MPC]
slope parameter G: (0.15) [*A]
effective diameter dE: 5.34 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: 720 km [*E]

other data, primary:
diameter dp: 5.19 km [*E]
axial ratios a/b, b/c:1.1, ? [*E]
rotation period RPp: 4.096 ± 0.0002 h [D26a]
amplitude in mag., rotational ΔM: 0.08 [D26a]
amplitude in mag., mutual events ΔM:0.06 [D26a]
pole direction Β, λ: ? , ?

other data, secondary:
diameter ds: >1.25 km [*E]
diameter ratio ds/dp: >0.24 [D26a]
component mag. difference ΔM: <3.1 [*D]
rotation period RPs: ?

-- (6311) Porubcan --discovery and notes:

Primary discovered 1990 Sep 15 from Palomar Observatory, California, USA by H. E. Holt. Alternate designation(s): 1990 RQ2, 1976 SR, 1978 GZ, 1981 BX, 1983 RW1, 1990 RQ2. Linked to prediscovery observations from 1950 Mar 21. Permanent number assigned 1995 Apr 15.

Named 1996 Jul 01 for Vladimir Porubcan (1940-) [MPC027462].

Companion discovered 2025 Dec 10 by R. Durkee, P. Pravec, N. Ruocco, M. Husarik, G. Cervak, D. Pray, P. Bacci, and M. Masestripieri using lightcurve observations from Shed of Science South Observatory, Pontotoc, Texas, USA; Osservatorio Astronomico Nastro Verde, Sorrento, Italy; Skalnate Pleso Observatory, Slovakia; Sugarloaf Mountain Observatory, South Deerfield, Massachusetts, USA; San Marcello Pistoiese Observatory, Italy. Announced 2026 Feb 24 [D26a].

--Links, more technical:

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--Links to ADS abstracts:

© 2026 by Wm. Robert Johnston.
Last modified 28 February 2026.
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