Skip Page Navigation
NASA JPL Caltech
NASA Logo - Jet Propulsion Laboratory + View the NASA Portal
+ Center for Near-Earth Object Studies
JPL Home Earth Solar System Stars & Galaxies Technology
JPL Solar System Dynamics
BODIES ORBITS EPHEMERIDES TOOLS PHYSICAL DATA DISCOVERY FAQ SITE MAP
IMPORTANT: The SSD Announcement email list is now available. Major changes are coming in the near future, including possible hostname and/or URL changes. To be notified of such changes, subscribe to this email list.

Please visit this page for more details.


JPL Small-Body Database Browser
Search: [ help ]  
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 2458600.5 (2019-Apr-27.0) TDB
Reference: JPL 101 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .1402330865078128 4.5628e-08  
a 2.583800893261519 7.7558e-09 au
q 2.221466519077812 1.1723e-07 au
i 10.19447279811673 4.9754e-06 deg
node 343.3897127689931 2.563e-05 deg
peri 348.3528869205088 3.0332e-05 deg
M 113.2828410303334 1.7738e-05 deg
tp 2458123.137142698370
(2018-Jan-04.63714270)
7.4119e-05 TDB
period 1517.004932658523
4.15
6.8304e-06
1.87e-08
d
yr
n .2373097095795903 1.0685e-09 deg/d
Q 2.946135267445225 8.8434e-09 au
  Orbit Determination Parameters
   # obs. used (total)      1933  
   data-arc span      54307 days (148.68 yr)  
   first obs. used      1871-03-22  
   last obs. used      2019-11-28  
   planetary ephem.      DE431  
   SB-pert. ephem.      SB431-N16  
   condition code      0  
   norm. resid. RMS      .46767  
   source      ORB  
   producer      Otto Matic  
   solution date      2019-Dec-03 20:01:28  

Additional Information
 Earth MOID = 1.21145 au 
 Jupiter MOID = 2.42025 au 
 T_jup = 3.387 
[ 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 8.33   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. 2019-January); 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 ]
ABOUT SSD CREDITS/AWARDS PRIVACY/COPYRIGHT GLOSSARY LINKS
FirstGov 2019-Dec-11 09:03 UT
(server date/time)  
NASA Home Page
Site Manager:   Ryan S. Park
Webmaster  Alan B. Chamberlin