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JPL Small-Body Database Browser
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101 Helena
Classification: Main-belt Asteroid          SPK-ID: 2000101
Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances | Close-Approach Data ]

[ show orbit diagram ]
Orbital Elements at Epoch 2459000.5 (2020-May-31.0) TDB
Reference: JPL 104 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .1405844546103274 4.5569e-08  
a 2.583077588999209 7.6862e-09 au
q 2.219937034933595 1.1709e-07 au
i 10.19686044290934 4.9661e-06 deg
node 343.3825019341222 2.4935e-05 deg
peri 348.3691396649701 2.9543e-05 deg
M 208.2023454733705 1.7706e-05 deg
tp 2459639.891950462058
(2022-Mar-01.39195046)
7.5627e-05 TDB
period 1516.367976067514
4.15
6.7681e-06
1.853e-08
d
yr
n .237409392496938 1.0597e-09 deg/d
Q 2.946218143064822 8.7668e-09 au
  Orbit Determination Parameters
   # obs. used (total)      2044  
   data-arc span      54376 days (148.87 yr)  
   first obs. used      1871-03-22  
   last obs. used      2020-02-05  
   planetary ephem.      DE431  
   SB-pert. ephem.      SB431-N16  
   condition code      0  
   norm. resid. RMS      .45578  
   source      ORB  
   producer      Otto Matic  
   solution date      2020-Feb-22 15:17:03  

Additional Information
 Earth MOID = 1.21083 au 
 Jupiter MOID = 2.42337 au 
 T_jup = 3.388 
[ 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 8.2   n/a MPO502153 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. 2019-August); 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          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 | Mission Design | Physical Parameters | Discovery Circumstances | Close-Approach Data ]
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