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20740 Semery (1999 XB228)
Classification: Main-belt Asteroid          SPK-ID: 2020740
Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances | Close-Approach Data ]

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Orbital Elements at Epoch 2459200.5 (2020-Dec-17.0) TDB
Reference: JPL 32 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .1655142896481261 1.7737e-08  
a 3.137345550348017 1.4185e-08 au
q 2.618070030201456 5.9081e-08 au
i 6.475807486302902 8.6731e-07 deg
node 110.9728632390289 3.5613e-06 deg
peri 202.3188590553416 8.2236e-06 deg
M 346.5004482004885 5.5073e-06 deg
tp 2459276.612994421639
(2021-Mar-03.11299442)
3.1167e-05 TDB
period 2029.747238925495
5.56
1.3766e-05
3.769e-08
d
yr
n .1773619853231461 1.2029e-09 deg/d
Q 3.656621070494579 1.6533e-08 au
  Orbit Determination Parameters
   # obs. used (total)      2280  
   data-arc span      24095 days (65.97 yr)  
   first obs. used      1954-09-27  
   last obs. used      2020-09-15  
   planetary ephem.      DE441  
   SB-pert. ephem.      SB441-N16  
   condition code      0  
   norm. resid. RMS      .49376  
   source      ORB  
   producer      Otto Matic  
   solution date      2021-Apr-13 03:29:46  

Additional Information
 Earth MOID = 1.60334 au 
 Jupiter MOID = 1.62647 au 
 T_jup = 3.180 
[ 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 12.93   n/a E2021B10  
diameter diameter 12.872 km 0.274 urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (http://adsabs.harvard.edu/abs/2011ApJ...741...68M)  
rotation period rot_per 7.970 h n/a LCDB (Rev. 2020-October); Warner et al., 2009 Result based on less than full coverage, so that the period may be wrong by 30 percent or so.
Published Reference List:
[Waszczak, A.; Chang, C.-K.; Ofeck, E.O.; Laher, F.; et al. (2015) Astron. J. 150, A75.]
[Durech, J.; Hanus, J.; Ali-Lagoa, V. (2018) Astron. Astrophys. 617, A57.]
geometric albedo albedo 0.067   0.010 urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (http://adsabs.harvard.edu/abs/2011ApJ...741...68M)  

20740 Sémery           Discovered 1999 Dec. 13 by the Lowell Observatory Near-Earth Object Search at the Anderson Mesa Station.
Alain Sémery (b. 1944) is an engineer at Paris Observatory. He has contributed to the design and development of many instruments aboard spacecraft involved in solar system exploration.
NOTE: some special characters may not display properly (any characters within {} are an attempt to place the proper accent above a character)
Reference: 20080718/MPCPages.arcLast Updated: 2008-07-18

[ show close-approach data ]
Alternate Designations
 1999 XB228 = 1954 SA1 = 1971 UC4 = 1998 MK25 
Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances | Close-Approach Data ]
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