Asteroid Radar Database
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101 Helena
Classification:  []
H:8.4 mag, G:0.15

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History of Radar Detections
Year Month Transmitter Receiver Frequency Obs
2001 Oct Arecibo Arecibo 2380 [A]

Radar-Based Physical Properties
                 [edit]
name symbol value units uncertainty reference notes
morphology
number of components N
morphological type
spectrum-based or image-based dimensions
maximum range extent Rmax km
minimum range extent Rmin km
maximum Doppler bandwidth Bmax Hz
minimum Doppler bandwidth Bmin Hz
effective diameter Deff km
quality code for size Q
shape-based dimensions
equivalent diameter Dequ km
extent along principal axis x Ex km
extent along principal axis y Ey km
extent along principal axis z Ez km
DEEVE extent along x Dx km
DEEVE extent along y Dy km
DEEVE extent along z Dz km
surface area A km2
volume V km3
spin
spin period Pspin h
spin rate ω deg/day
YORP acceleration ω̇ deg/day2
spin axis ecliptic longitude λ deg
spin axis ecliptic latitude β deg
reflectivity
radar cross-section OC σOC km2
radar cross-section SC σSC km2
radar cross-section σT km2
projected area Aproj km2
radar albedo OC σ̂OC
radar albedo SC σ̂SC
radar albedo σ̂T
circular polarization ratio μC

Orbital Elements at Epoch 2025-05-05 00:00 TT from E2025-H23 (heliocentric ecliptic J2000)
Element Value Units
e 0.140582
a 2.5835577 AU
i 10.19186 deg
om 343.36447 deg
w 347.78343 deg
ma 276.16155 deg
n 0.23734322 deg/d

Link to complete orbital information at Minor Planet Center