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1872 Helenos (1971 FG)
Classification: Jupiter Trojan          SPK-ID: 2001872
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 2459200.5 (2020-Dec-17.0) TDB
Reference: JPL 25 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .04903770691881038 4.2708e-08  
a 5.321153693867414 8.7419e-08 au
q 5.060216518557598 2.8722e-07 au
i 14.64015044110235 4.7371e-06 deg
node 188.7871740341844 1.4997e-05 deg
peri 114.6330107860831 5.4302e-05 deg
M 309.0948175447888 5.3341e-05 deg
tp 2459834.466966496171
(2022-Sep-11.96696650)
0.00066828 TDB
period 4483.396324911077
12.27
0.00011048
3.025e-07
d
yr
n .08029626959359658 1.9787e-09 deg/d
Q 5.58209086917723 9.1706e-08 au
  Orbit Determination Parameters
   # obs. used (total)      1914  
   data-arc span      24182 days (66.21 yr)  
   first obs. used      1954-12-22  
   last obs. used      2021-03-07  
   planetary ephem.      DE441  
   SB-pert. ephem.      SB441-N16  
   condition code      0  
   norm. resid. RMS      .46309  
   source      ORB  
   producer      Otto Matic  
   solution date      2021-Apr-12 13:03:25  

Additional Information
 Earth MOID = 4.07545 au 
 Jupiter MOID = .0664304 au 
 T_jup = 2.932 
[ hide covariance matrix ]
Orbital Elements at Epoch 2457456.5 (2016-Mar-09.0) TDB
Reference: JPL 25 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .04761225396524651 4.2469e-08  
q 5.06499441769813 2.86e-07 au
tp 2455377.208824981152
(2010-Jun-29.70882498)
0.00066997 TDB
node 188.7914903020213 1.4998e-05 deg
peri 116.2359660173296 5.6065e-05 deg
i 14.64130074720503 4.7374e-06 deg
  Orbit Determination Parameters
   # obs. used (total)      1914  
   data-arc span      24182 days (66.21 yr)  
   first obs. used      1954-12-22  
   last obs. used      2021-03-07  
   planetary ephem.      DE441  
   SB-pert. ephem.      SB441-N16  
   condition code      0  
   norm. resid. RMS      .46309  
   source      ORB  
   producer      Otto Matic  
   solution date      2021-Apr-12 13:03:25  

Additional Information
 Jupiter MOID = .0664304 au 
 T_jup = 2.932 
Orbit Covariance (6×6)
  e q tp node peri i
e 1.8035782344175E-15 -1.181725179548275E-14 -3.665618127090713E-12 1.704952831213225E-15 -3.347237270582967E-13 5.196416383120033E-16
q -1.181725179548275E-14 8.179635166451757E-14 2.590872356121468E-11 -8.860664141595496E-15 2.57000866381726E-12 -4.459000909445783E-15
tp -3.665618127090713E-12 2.590872356121468E-11 4.488664100260406E-7 -8.978416049699526E-11 3.615401057578293E-8 1.891707655050682E-11
node 1.704952831213225E-15 -8.860664141595496E-15 -8.978416049699526E-11 2.249383646816863E-10 -2.246499380604356E-10 2.078853641080797E-11
peri -3.347237270582967E-13 2.57000866381726E-12 3.615401057578293E-8 -2.246499380604356E-10 3.143281067609105E-9 -1.872809300634451E-11
i 5.196416383120033E-16 -4.459000909445783E-15 1.891707655050682E-11 2.078853641080797E-11 -1.872809300634451E-11 2.244249815957509E-11

Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances ]

Physical Parameter Table
Parameter Symbol Value Units Sigma Reference Notes
absolute magnitude H 10.88   n/a E2021B10  
diameter diameter 34.046 km 0.603 urn:nasa:pds:neowise_diameters_albedos::2.0[jupiter_trojans] (http://adsabs.harvard.edu/abs/2012ApJ...759...49G)  
geometric albedo albedo 0.067   0.012 urn:nasa:pds:neowise_diameters_albedos::2.0[jupiter_trojans] (http://adsabs.harvard.edu/abs/2012ApJ...759...49G)  

1872 Helenos (1971 FG)          Discovered 1971-Mar-24 by Van Houten, C. J. at Palomar
Discovered by C. J. van Houten and I. van Houten-Groeneveld, Leiden, on plates exposed by T. Gehrels in a survey of faint Trojans with the 122 cm Schmidt camera at Palomar.
Reference: DISCOVERY.DBLast Updated: 2003-08-29
Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances ]
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