Asteroids with Satellites Database--Johnston's Archive

(4788) Simpson

compiled by Wm. Robert Johnston
last updated 14 February 2021

--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: 2.2626167213 AU
orbital period P: 3.4034273812 yr
(= 1243.1253289 d)
eccentricity e: 0.129443116
perihelion distance q: 1.969736563 AU
aphelion distance Q: 2.5554968799 AU
inclination i: 4.3187853°
argument of perihelion ω: 110.318461°
ascending node Ω: 277.176547°
mean anomaly M: 316.513479°
perihelion passage TP: 2020 Oct 28.164432
Epoch: 2020 May 31
data arc: 1976-2020 (2088 obs.)
Earth MOID: 0.979429 AU
Jupiter Tisserand invariant TJ: 3.604


orbital data, secondary:
semimajor axis as: 5.7 km [*E]
separation/primary radius as/rp:3.2 [*E]
separation/Hill radius as/rH:0.011 [*E]
orbital period Ps: 0.6242 ± 0.0004 d [S21a]
eccentricity es: ?
normalized ang. mom. αL: ?

other data, system (combined):
absolute mag. H: 13.7 [MPC]
slope parameter G: (0.15) [*A]
effective diameter dE: 3.58 ± 0.7 km [M**]
geometric albedo: 0.5 ± 0.174 [M**]
color index U-B: ?
color index B-V: ?
taxonomic type: ?
mass m: ?
density ρ: (1.6 g/cm3) [*A]
Hill radius rH: 540 km [*E]

other data, primary:
diameter dp: 3.53 km [*D]
rotation period RPp: 2.81752 ± 0.00008 h [S21a]
amplitude in mag., rotational ΔM: 0.18 [S21a]
amplitude in mag., mutual events ΔM:0.05 ±0.02 [S21a]
pole direction Β, λ: ? , ?


other data, secondary:
diameter ds: >0.6 km [*D]
diameter ratio ds/dp: >0.17 [S21a]
component mag. difference ΔM: <3.8 [S21a]
rotation period RPs: ?

-- (4788) Simpson --discovery and notes:

Primary discovered 1986 Oct 04 from Flagstaff, Arizona by E. Bowell. Alternate designation(s): 1986 TL1, 1976 YJ1, 1979 RN1, 1984 AS. Linked to prediscovery observations from 1976 Dec 16. Permanent number assigned 1991 Apr 28.

Named 1991 Jun 27 for Robert W. L. Simpson (1921-1997) [MPC018465].

Companion discovered 2020 Dec by P. Sogorb, et al. using lightcurve observations. Announced 2021 Jan 07 [S21a].

--Links, more technical:

--Links, less technical:

--Links to ADS abstracts:


© 2021 by Wm. Robert Johnston.
Last modified 14 February 2021.
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