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20975 (1981 ER4)
Classification: Main-belt Asteroid          SPK-ID: 2020975
Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances ]

[ show orbit diagram ]
Orbital Elements at Epoch 2458600.5 (2019-Apr-27.0) TDB
Reference: JPL 25 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .1178260779681086 2.9265e-08  
a 2.943291125359991 1.4651e-08 au
q 2.596494675740483 8.8682e-08 au
i 10.05598386029108 4.128e-06 deg
node 211.449339678702 2.0396e-05 deg
peri 244.6080110552413 3.005e-05 deg
M 263.7169256326563 2.0501e-05 deg
tp 2459093.782497906756
(2020-Sep-01.28249791)
0.00010554 TDB
period 1844.370886713838
5.05
1.3771e-05
3.77e-08
d
yr
n .1951885071453394 1.4574e-09 deg/d
Q 3.290087574979499 1.6378e-08 au
  Orbit Determination Parameters
   # obs. used (total)      1552  
   data-arc span      17731 days (48.54 yr)  
   first obs. used      1971-05-14  
   last obs. used      2019-11-29  
   planetary ephem.      DE431  
   SB-pert. ephem.      SB431-N16  
   condition code      0  
   norm. resid. RMS      .50714  
   source      ORB  
   producer      Otto Matic  
   solution date      2019-Dec-14 00:48:03  

Additional Information
 Earth MOID = 1.6321 au 
 Jupiter MOID = 2.00845 au 
 T_jup = 3.239 
[ show covariance matrix ]

Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances ]

Physical Parameter Table
Parameter Symbol Value Units Sigma Reference Notes
absolute magnitude H 13.7   n/a MPO502323  
diameter diameter 5.240 km 0.316 urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (http://adsabs.harvard.edu/abs/2011ApJ...741...68M)  
geometric albedo albedo 0.281   0.046 urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (http://adsabs.harvard.edu/abs/2011ApJ...741...68M)  

20975 (1981 ER4)          Discovered 1981-Mar-02 by Bus, S. J. at Siding Spring
Reference: 20010208/Numbers.arcLast Updated: 2004-04-19

Alternate Designations
 1981 ER4 = 1999 VN2 
Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances ]
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