Asteroids with Satellites Database--Johnston's Archive

(1990) Pilcher

compiled by Wm. Robert Johnston
last updated 23 Apr 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: 2.1738042485 AU
orbital period P: 3.2050798372 yr
(= 1170.6554105 d)
eccentricity e: 0.051858151
perihelion distance q: 2.06107478 AU
aphelion distance Q: 2.2865337173 AU
inclination i: 3.13482102°
argument of perihelion ω: 12.796389°
ascending node Ω: 193.568371°
mean anomaly M: 285.494231°
perihelion passage TP: 2023 Oct 25.279393
Epoch: 2023 Feb 25
data arc: 1937-2023 (4384 obs.)
Earth MOID: 1.05665 AU
Jupiter Tisserand invariant TJ: 3.683

orbital data, secondary:
semimajor axis as: 12 km [*E]
separation/primary radius as/rp:3.6 [*E]
separation/Hill radius as/rH:0.011 [*E]
orbital period Ps: 0.71442 ± 0.00008 d [B23j]
eccentricity es: ?
normalized ang. mom. αL: ?

other data, system (combined):
absolute mag. H: 12.91 [MPC]
slope parameter G: (0.15) [*A]
effective diameter dE: 6.75 ± 0.17 km [M**]
geometric albedo: 0.215 ± 0.039 [M**]
color index U-B: 0.504 [JPL]
color index B-V: 0.85 [JPL]
taxonomic type: S (Tholen) [JPL]
mass m: ?
density ρ: (1.6 g/cm3) [*A]
Hill radius rH: 1100 km [*E]

other data, primary:
diameter dp: 6.59 ± 0.17 km [*D]
rotation period RPp: 2.84096 ± 0.00007 h [B23j]
amplitude in mag., rotational ΔM: 0.11 [B23j]
amplitude in mag., mutual events ΔM:0.05 [B23j]
pole direction Β, λ: ? , ?

other data, secondary:
diameter ds: >1.45 km [*D]
diameter ratio ds/dp: >0.22 [B23j]
component mag. difference ΔM: <3.3 [*D]
rotation period RPs: ?

-- (1990) Pilcher --discovery and notes:

Primary discovered 1956 Mar 09 from Heidelberg, Germany by K. Reinmuth. Alternate designation(s): 1956 EE, 1937 JL, 1940 FA, 1959 CE1, 1964 VS2, 1972 EC, 1972 GO, 1973 QM. Linked to prediscovery observations from 1937 May 03. Permanent number assigned -.

Named 1982 Apr 08 for Frederick Pilcher (1939-) [MPC006833].

Companion discovered 2022 Dec 29 by V. Benishek, P. Pravec, F. Pilcher, M. Husarik, A. Voitko, D. Tomko, M. Pikler, G. Cervak, A. Marchini, and R. Papini using lightcurve observations from Sopot Observatory, Serbia; Organ Mesa Observatory, New Mexico, USA; Skalnate Pleso Observatory; Astronomical Observatory of the University of Siena. Announced 2023 Apr 22 [B23j].

--Links, more technical:

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--Links to ADS abstracts:

© 2023 by Wm. Robert Johnston.
Last modified 23 Apr 2023.
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