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101 Helena (A868 PA)
Classification: Main-belt Asteroid          SPK-ID: 2000101
Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances ]

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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.


Orbital Elements at Epoch 2459396.5 (2021-Jul-01.0) TDB
Reference: JPL 113 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .1408702107727302 4.2233e-08  
a 2.582674076650012 6.6544e-09 au
q 2.218852235115059 1.0934e-07 au
i 10.19761339656432 4.7174e-06 deg
node 343.3844515622403 2.2589e-05 deg
peri 348.4144381803802 2.7046e-05 deg
M 302.2047505741244 1.6927e-05 deg
tp 2459639.884251668890
(2022-Mar-01.38425167)
7.1642e-05 TDB
period 1516.012673553281
4.15
5.8591e-06
1.604e-08
d
yr
n .237465033294359 9.1776e-10 deg/d
Q 2.946495918184966 7.5918e-09 au
  Orbit Determination Parameters
   # obs. used (total)      2553  
   data-arc span      54927 days (150.38 yr)  
   first obs. used      1871-03-22  
   last obs. used      2021-08-09  
   planetary ephem.      DE441  
   SB-pert. ephem.      SB441-N16  
   condition code      0  
   norm. resid. RMS      .41803  
   source      ORB  
   producer      Otto Matic  
   solution date      2021-Aug-25 21:03:48  

Additional Information
 Earth MOID = 1.20898 au 
 Jupiter MOID = 2.42306 au 
 T_jup = 3.388 
[ 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 8.23   n/a E2021B10 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. 2020-October); 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 0.854   0.020 EAR-A-5-DDR-UBV-MEAN-VALUES-V1.2 #obs=12; phase (min.=3.93, mean=10.53, max.=24.72) deg.
U-B UB 0.426   0.033 EAR-A-5-DDR-UBV-MEAN-VALUES-V1.2 #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 (A868 PA)          Discovered 1868-Aug-15 by Watson, J. C. at Ann Arbor
Reference: DISCOVERY.DBLast Updated: 2003-08-29
Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances ]
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