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21065 Jamesmelka (1991 NM)
Classification: Main-belt Asteroid          SPK-ID: 2021065
Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances | Close-Approach Data ]

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Orbital Elements at Epoch 2459396.5 (2021-Jul-01.0) TDB
Reference: JPL 43 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .2082756820931007 2.0999e-08  
a 3.135937595118921 1.5226e-08 au
q 2.48279805349413 6.8765e-08 au
i 16.59643172914647 4.2504e-07 deg
node 249.675410917041 1.3164e-06 deg
peri 27.26930204157954 2.8672e-06 deg
M 147.2163790346164 5.6483e-06 deg
tp 2458567.025240602532
(2019-Mar-24.52524060)
2.9081e-05 TDB
period 2028.381049318387
5.55
1.4773e-05
4.045e-08
d
yr
n .1774814451756852 1.2926e-09 deg/d
Q 3.789077136743713 1.8397e-08 au
  Orbit Determination Parameters
   # obs. used (total)      2048  
   data-arc span      10860 days (29.73 yr)  
   first obs. used      1991-07-10  
   last obs. used      2021-04-03  
   planetary ephem.      DE441  
   SB-pert. ephem.      SB441-N16  
   condition code      0  
   norm. resid. RMS      .43239  
   source      ORB  
   producer      Otto Matic  
   solution date      2021-Jul-08 18:30:08  

Additional Information
 Earth MOID = 1.47814 au 
 Jupiter MOID = 1.35838 au 
 T_jup = 3.115 
[ show covariance matrix ]

Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances | Close-Approach Data ]

Physical Parameter Table
Parameter Symbol Value Units Sigma Reference Notes
absolute magnitude H 12.85   n/a E2021B10  
diameter diameter 15.452 km 0.218 urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (http://adsabs.harvard.edu/abs/2011ApJ...741...68M)  
geometric albedo albedo 0.107   0.010 urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (http://adsabs.harvard.edu/abs/2011ApJ...741...68M)  

21065 Jamesmelka           Discovered 1991 July 10 by E. F. Helin at Palomar.
James Melka (b. 1942) is an amateur astronomer who has observed and imaged Mars during nine apparitions from 1971 through 2012. He recorded the initial clouds of the 1971 and 2007 planet-wide dust storms and used Mars Global Surveyor images to identify three craters containing massive black sand dunes.
NOTE: some special characters may not display properly (any characters within {} are an attempt to place the proper accent above a character)
Reference: MPC batch dated 2013-08-21Last Updated: 2014-08-13

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Alternate Designations
 1991 NM = 1998 WJ21 
Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances | Close-Approach Data ]
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