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JPL Small-Body Database Browser
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949 Hel (A921 EM)
Classification: Main-belt Asteroid          SPK-ID: 2000949
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 35 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .1924869427510898 3.9148e-08  
a 3.004002706906407 1.4725e-08 au
q 2.425771409837994 1.164e-07 au
i 10.69987702884919 4.4746e-06 deg
node 321.1670200037671 2.3139e-05 deg
peri 249.4546246810995 2.5779e-05 deg
M 282.5980975364308 1.3707e-05 deg
tp 2459009.382045860713
(2020-Jun-08.88204586)
7.3663e-05 TDB
period 1901.730213661588
5.21
1.3983e-05
3.828e-08
d
yr
n .1893012991084875 1.3919e-09 deg/d
Q 3.582234003974819 1.756e-08 au
  Orbit Determination Parameters
   # obs. used (total)      2417  
   data-arc span      33320 days (91.23 yr)  
   first obs. used      1928-09-05  
   last obs. used      2019-11-27  
   planetary ephem.      DE431  
   SB-pert. ephem.      SB431-N16  
   condition code      0  
   norm. resid. RMS      .43643  
   source      ORB  
   producer      Otto Matic  
   solution date      2019-Dec-03 20:14:32  

Additional Information
 Earth MOID = 1.44689 au 
 Jupiter MOID = 1.58087 au 
 T_jup = 3.197 
[ 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 9.8   n/a MPO347521  
diameter diameter 63.494 km 0.743 urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (http://adsabs.harvard.edu/abs/2014ApJ...791..121M)  
rotation period rot_per 8.215 h n/a LCDB (Rev. 2019-January); Warner et al., 2009 Result based on less than full coverage, so that the period may be wrong by 30 percent or so.
Published Reference List:
[Brines, P.; Lozano, J.; Rodrigo, O.; Fornas, A.; et al. (2017) Minor Planet Bull. 44, 145-149.]
geometric albedo albedo 0.058   0.013 urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (http://adsabs.harvard.edu/abs/2014ApJ...791..121M)  

949 Hel (A921 EM)          Discovered 1921-Mar-11 by Wolf, M. at Heidelberg
Reference: DISCOVERY.DBLast Updated: 2003-08-29

[ show close-approach data ]
Alternate Designations
 A921 EM = 1952 DN = 1954 SN1 
Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances | Close-Approach Data ]
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