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24 Themis (A853 GA)
Classification: Main-belt Asteroid          SPK-ID: 2000024
Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances | Close-Approach Data ]

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For accurate long-term ephemerides, please instead use our Horizons system.This orbit viewer was implemented using two-body methods, and hence should not be used for determining accurate long-term trajectories (over several years or decades) or planetary encounter circumstances.

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Orbital Elements at Epoch 2459000.5 (2020-May-31.0) TDB
Reference: JPL 117 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .124421895007763 2.7108e-08  
a 3.135384856768119 6.5934e-09 au
q 2.745274331310386 8.5007e-08 au
i .7516514658928085 3.0397e-06 deg
node 35.92035471802042 0.00022965 deg
peri 106.9819468385035 0.00022996 deg
M 66.20951534192203 1.294e-05 deg
tp 2458627.548275510341
7.2381e-05 TDB
period 2027.844791234498
n .1775283796650145 5.5999e-10 deg/d
Q 3.525495382225852 7.4137e-09 au
  Orbit Determination Parameters
   # obs. used (total)      4052  
   data-arc span      61157 days (167.44 yr)  
   first obs. used      1853-04-27  
   last obs. used      2020-10-05  
   planetary ephem.      DE431  
   SB-pert. ephem.      SB431-N16  
   condition code      0  
   norm. resid. RMS      .5059  
   source      ORB  
   producer      Otto Matic  
   solution date      2020-Nov-13 04:34:14  

Additional Information
 Earth MOID = 1.75798 au 
 Jupiter MOID = 1.48763 au 
 T_jup = 3.200 
[ 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 7.3   n/a MPO473760  
magnitude slope G 0.19   n/a PDS3 (MPC 17257) Fit
diameter diameter 198 km n/a J.G. Williams (E-mail September 1990) based on IRTF albedo of 0.067
rotation period rot_per 8.374 h n/a LCDB (Rev. 2019-August); Warner et al., 2009 Published Reference List:
[Tedesco, E.F. (1979) PhD Dissertation, New. Mex. State Univ. 280pp.]
[Van Houten-Groeneveld, I.; van Houten, C.J.; Zappala, V. (1979) Astron. Astrophys. Suppl. Ser. 35, 223-232.]
[Harris, A.W.; Young, J.W. (1983) Icarus 54, 59-109.]
[Harris, A.W.; Young, J.W.; Bowell, E.; Martin, L.J.; et al. (1989) Icarus 77, 171-186.]
[Chiorny, V.G.; Shevchenko, V.G.; Krugly, Yu.N.; Velichko, F.P.; Gaftonyuk, N.M. (2007) Planet. Space Sci. 55, 986-997.]
[Ditteon, R.; Hawkins, S. (2007) Minor Planet Bull. 34, 59-64.]
[Higley, S.; Hardersen, P.; Dyvig, R. (2008) Minor Planet Bull. 35, 63-66.]
[Pilcher, F. (2012)]
[Pilcher, F. (2013) Minor Planet Bull. 40, 85-87.]
[Pilcher, F. (2014) Minor Planet Bull. 41, 250-252.]
[Hanus, J.; Durech, J.; Oszkiewicz, D.A.; Behrend, R.; et al. (2016) Astron. Astrophys. 586, A108.]
[Behrend, R. (2017) Observatoire de Geneve web site,]
[Viikinkoski, M.; Hanus, J.; Kaasalainen, M.; Marchis, F.; Durech, J. (2017) Astron. Astrophys. 607, A117.]
geometric albedo albedo 0.067   n/a J.G. Williams (E-mail September 1990) IRTF
B-V BV 0.684   0.030 EAR-A-5-DDR-UBV-MEAN-VALUES-V1.2 #obs=10; phase (min.=.16, mean=9.29, max.=18.36) deg.
U-B UB 0.336   0.024 EAR-A-5-DDR-UBV-MEAN-VALUES-V1.2 #obs=8; phase (min.=.16, mean=8.75, max.=18.36) deg.
Tholen spectral type spec_T C   n/a EAR-A-5-DDR-TAXONOMY-V4.0 used 7 color indices; used ground-based radiometric albedo
SMASSII spectral type spec_B B   n/a EAR-A-5-DDR-TAXONOMY-V4.0 based on a high-resolution spectrum by Xu et al. (1995) or Bus and Binzel (2002)

24 Themis (A853 GA)          Discovered 1853-Apr-05 by De Gasparis, A. at Naples
Reference: DISCOVERY.DBLast Updated: 2003-08-29

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Alternate Designations
 A853 GA = 1947 BA = 1955 OH 
Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances | Close-Approach Data ]
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