Asteroids with Satellites Database--Johnston's Archive

(939) Isberga

compiled by Wm. Robert Johnston
last updated 16 November 2014

--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: 2.2467449376 AU
orbital period P: 3.367678759 yr
(= 1230.0678981 d)
eccentricity e: 0.177463926
perihelion distance q: 1.848028761 AU
aphelion distance Q: 2.6454611141 AU
inclination i: 2.5877179°
argument of perihelion ω: 5.904982°
ascending node Ω: 327.135247°
mean anomaly M: 13.610505°
perihelion passage TP: 2014 Oct 23.494874
Epoch: 2014 Dec 09
data arc: 1920-2014 (2091 obs.)
Earth MOID: 0.838312 AU
Jupiter Tisserand invariant TJ: 3.608


orbital data, secondary:
binary dynamical type:U [L15a]
semimajor axis as: 33 ± 4.5 km [C14c]
separation/primary radius as/rp:5 [C14c]
separation/Hill radius as/rH:0.014 [*D]
orbital period Ps: 1.1096 ± 0.000004 d [C14c]
eccentricity es: <0.1 [C14c]
normalized ang. mom. αL: ?

other data, system (combined):
absolute mag. H: 12.14 [MPC]
slope parameter G: (0.15) [*A]
effective diameter dE: 12.9 ± 1.9 km [C14c]
geometric albedo: 0.14 ± 0.075 [C14c]
color index U-B: 0.54 [JPL]
color index B-V: 0.93 [JPL]
taxonomic type: S (Tholen) [JPL]
mass m: 3.61x1015 ± 1.74x1015 kg [C14c]
density ρ: 2.91 ± 1.86 g/cm3[C14c]
Hill radius rH: 2300 km [*D]

other data, primary:
diameter dp: 12.4 ± 1.8 km [C14c]
dimensions :14.5 x 11.8 x 11.1km [*D]
axial ratios a/b, b/c:1.23, 1.06 [C14c]
volume :1000[C14c]
rotation period RPp: 2.91695 ± 0.0001 h [C14c]
amplitude in mag., rotational ΔM: 0.25 [M08e]
amplitude in mag., mutual events ΔM:0.15 [M08e]
pole direction Β, λ: ? , ?


other data, secondary:
diameter ds: 3.6 ± 0.5 km [C14c]
dimensions :3.8 x 3.5 x 3.5km [*D]
axial ratios a/b, b/c:1.1;1 [C14c]
diameter ratio ds/dp: 0.29 ± 0.02 [C14c]
component mag. difference ΔM: 2.7 [*D]
rotation period RPs: 26.6304 ± 0.0001 h [C14c]

-- (939) Isberga --discovery and notes:

Primary discovered 1920 Oct 04 from Heidelberg, Germany by K. Reinmuth. Alternate designation(s): 1920 HR, 1930 QP, 1957 QE, 1957 UU. Permanent number assigned -.

Named - for a girl's name.

Companion discovered 2006 Feb 26 using lightcurve observations. Announced 2007.

--Links, more technical:

--Links, less technical:

--Links to ADS abstracts:


© 2007-2008, 2014 by Wm. Robert Johnston.
Last modified 16 November 2014.
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