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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 2459200.5 (2020-Dec-17.0) TDB
Reference: JPL 33 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .1181169545463086 2.6998e-08  
a 2.944847305575272 1.255e-08 au
q 2.597010910236818 8.0232e-08 au
i 10.05371092804288 3.4532e-06 deg
node 211.4417891754836 1.9488e-05 deg
peri 244.400326494615 2.8966e-05 deg
M 20.98518228955882 1.9142e-05 deg
tp 2459092.902335770732
(2020-Aug-31.40233577)
9.8171e-05 TDB
period 1845.833816836039
5.05
1.1799e-05
3.23e-08
d
yr
n .1950338089574496 1.2467e-09 deg/d
Q 3.292683700913725 1.4032e-08 au
  Orbit Determination Parameters
   # obs. used (total)      1966  
   data-arc span      18203 days (49.84 yr)  
   first obs. used      1971-05-14  
   last obs. used      2021-03-15  
   planetary ephem.      DE441  
   SB-pert. ephem.      SB441-N16  
   condition code      0  
   norm. resid. RMS      .48915  
   source      ORB  
   producer      Otto Matic  
   solution date      2021-Apr-13 03:35:32  

Additional Information
 Earth MOID = 1.63223 au 
 Jupiter MOID = 2.00559 au 
 T_jup = 3.238 
[ 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 13.72   n/a E2021B10  
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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