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101 Helena
Classification: Main-belt Asteroid          SPK-ID: 2000101
Ephemeris | Orbit Diagram | Orbital Elements | Physical Parameters | Discovery Circumstances | Close-Approach Data ]

[ show orbit diagram ]
Orbital Elements at Epoch 2457400.5 (2016-Jan-13.0) TDB
Reference: JPL 86 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .1397954061794272 5.0046e-08  
a 2.585514766976436 8.7546e-09 au
q 2.224071679944058 1.3013e-07 au
i 10.20146325263818 5.6917e-06 deg
node 343.4253976243193 2.5762e-05 deg
peri 347.7595975379785 2.9716e-05 deg
M 189.1787564765425 1.6113e-05 deg
tp 2458121.040404479550
(2018-Jan-02.54040448)
6.9214e-05 JED
period 1518.514560965701
4.16
7.7126e-06
2.112e-08
d
yr
n .2370737885918312 1.2041e-09 deg/d
Q 2.946957854008814 9.9785e-09 au
  Orbit Determination Parameters
   # obs. used (total)      1225  
   data-arc span      52866 days (144.74 yr)  
   first obs. used      1871-03-22  
   last obs. used      2015-12-18  
   planetary ephem.      DE431  
   SB-pert. ephem.      SB431-BIG16  
   condition code      0  
   fit RMS      .55618  
   data source      ORB  
   producer      Otto Matic  
   solution date      2016-Jan-04 12:31:04  

Additional Information
 Earth MOID = 1.21296 au 
 Jupiter MOID = 2.40928 au 
 T_jup = 3.386 
[ show covariance matrix ]

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

Physical Parameter Table
Parameter Symbol Value Units Sigma Reference Notes
absolute magnitude H 8.33 mag n/a IRAS-A-FPA-3-RDR-IMPS-V6.0 IRAS observations used: 15
magnitude slope G 0.35   n/a PDS3 (MPC 17257) Fit
diameter diameter 65.84 km 1.3 IRAS-A-FPA-3-RDR-IMPS-V6.0 IRAS observations used: 15
rotation period rot_per 23.080 h n/a LCDB (Rev. 2015-December); Warner et al., 2009 Published Reference List:
[Lagerkvist, C.-I.; Rickman, H. (1981) Astron. Astrophys. Suppl. Ser. 45, 177-179.]
[Harris, A.W.; Young, J.W. (1989) Icarus 81, 314-364.]
geometric albedo albedo 0.1898   0.008 IRAS-A-FPA-3-RDR-IMPS-V6.0 IRAS observations used: 15
B-V BV .854 mag .020 EAR-A-5-DDR-UBV-MEAN-VALUES-V1.1 #obs=12; phase (min.=3.93, mean=10.53, max.=24.72) deg.
U-B UB .426 mag .033 EAR-A-5-DDR-UBV-MEAN-VALUES-V1.1 #obs=12; phase (min.=3.93, mean=10.53, max.=24.72) deg.
Tholen spectral type spec_T S   n/a EAR-A-5-DDR-TAXONOMY-V4.0 used 7 color indices; used ground-based radiometric albedo
SMASSII spectral type spec_B S   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)

101 Helena          Discovered 1868-Aug-15 by Watson, J. C. at Ann Arbor
Reference: DISCOVERY.DBLast Updated: 2003-08-29

[ show close-approach data ]
Ephemeris | Orbit Diagram | Orbital Elements | Physical Parameters | Discovery Circumstances | Close-Approach Data ]
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