Asteroids with Satellites Database--Johnston's Archive

(3959) Irwin

compiled by Wm. Robert Johnston
last updated 19 February 2023

--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: 2.2586517612 AU
orbital period P: 3.3945492741 yr
(= 1239.8591224 d)
eccentricity e: 0.187459657
perihelion distance q: 1.835245677 AU
aphelion distance Q: 2.6820578452 AU
inclination i: 3.28523173°
argument of perihelion ω: 198.1795707°
ascending node Ω: 210.793769°
mean anomaly M: 37.438363°
perihelion passage TP: 2022 Oct 19.060289
Epoch: 2023 Feb 25
data arc: 1954-2023 (3045 obs.)
Earth MOID: 0.844144 AU
Jupiter Tisserand invariant TJ: 3.596

orbital data, secondary:
semimajor axis as: 6.6 km [*E]
separation/primary radius as/rp:3.3 [*E]
separation/Hill radius as/rH:0.012 [*E]
orbital period Ps: 0.6517 ± 0.0002 d [B23d]
eccentricity es: ?
normalized ang. mom. αL: ?

other data, system (combined):
absolute mag. H: 14.08 [MPC]
slope parameter G: (0.15) [*A]
effective diameter dE: 4.14 ± 0.33 km [M**]
geometric albedo: 0.259 ± 0.089 [M**]
color index U-B: ?
color index B-V: ?
taxonomic type: ?
mass m: ?
density ρ: (1.6 g/cm3) [*A]
Hill radius rH: 570 km [*E]

other data, primary:
diameter dp: 3.98 ± 0.32 km [*D]
rotation period RPp: 3.2591 ± 0.0003 h [B23d]
amplitude in mag., rotational ΔM: 0.11 [B23d]
amplitude in mag., mutual events ΔM:0.135 ±0.045 [B23d]
pole direction Β, λ: ? , ?

other data, secondary:
diameter ds: >1.15 km [*D]
diameter ratio ds/dp: >0.29 [B23d]
component mag. difference ΔM: <2.7 [*D]
rotation period RPs: ?

-- (3959) Irwin --discovery and notes:

Primary discovered 1954 Oct 28 from Brooklyn, Indiana, USA by Goethe Link Observatory. Alternate designation(s): 1954 UN2, 1981 TP4, 1981 UX10, 1986 CY1. Permanent number assigned 1989 Feb 20.

Named 1995 Sep 09 for John B. Irwin (1909-1997) [MPC025652].

Companion discovered 2022 Nov 14 by V. Benishek, F. Salvaggio, R. Papini, A. Marchini, P. Pravec, F. Pilcher, and R. Durkee using lightcurve observations from Sopot Observatory, Serbia; Wild Boar Remote Observatory, Florence, Italy; Astronomical Observatory of the University of Siena; Organ Mesa Observatory, Las Cruces, New Mexico, USA; Shed of Science South Observatory, Pontotoc, Texas, USA. Announced 2023 Feb 09 [B23d].

--Links, more technical:

--Links, less technical:

--Links to ADS abstracts:

© 2023 by Wm. Robert Johnston.
Last modified 19 February 2023.
Return to Home. Return to Astronomy and Space. Return to Asteroids with Satellites.