Asteroid Radar Database
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99942 Apophis (2004 MN4)
Classification: ATE [NEO, PHA]
H:19 mag, G:0.15

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History of Radar Detections
Year Month Transmitter Receiver Frequency Obs
2005 Jan Arecibo Arecibo 2380 [A]
2005 Aug Arecibo Arecibo 2380 [A]
2006 May Arecibo Arecibo 2380 [A]
2012 Dec Goldstone Goldstone 8560 [G]
2013 Feb Arecibo Arecibo 2380 [A]
2021 Mar Goldstone Goldstone 8650 [G, G > GBT]
2021 Mar Goldstone Green Bank Telescope 8650 [G > GBT]

Radar-Based Physical Properties
name symbol value units uncertainty reference notes
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 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
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 0.1 0.2 2008Icar..198..294B Date: 2006T

Orbital Elements at Epoch 2024-03-31 00:00 TT from E2024-JQ5 (heliocentric ecliptic J2000)
Element Value Units
e 0.1912907
a 0.9225521 AU
i 3.33974 deg
om 203.91537 deg
w 126.68323 deg
ma 5.22319 deg
n 1.11228912 deg/d

Link to complete orbital information at Minor Planet Center

Earth Close-Approach Data (+/- 10 years)
date nominal distance RTT SNR/run at Arecibo
2020-01-05 04:06:00 0.44771 446.8 0.2
2020-10-12 08:38:00 0.21628 215.8 2.2
2021-03-06 01:15:00 0.11265 112.4 20.9
2027-12-29 14:23:00 0.29361 293.0 0.7
2028-09-12 04:11:00 0.25657 256.1 1.2
2029-04-13 21:46:00 0.00025 0.3 0.0
2029-11-26 21:39:00 0.29996 299.4 0.7

Link to complete Close-Approach Data on SBDB at JPL