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117P/Helin-Roman-Alu 1
Classification: Jupiter-family Comet          SPK-ID: 1000121
Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances | Close-Approach Data ]

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:
Orbital Elements at Epoch 2457126.5 (2015-Apr-14.0) TDB
Reference: JPL K222/16 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .253890770060263 1.1399e-07  
a 4.095738025802124 4.7211e-07 au
q 3.055867944466121 7.7908e-07 au
i 8.69723082105739 6.615e-06 deg
node 58.88476872402472 4.4781e-05 deg
peri 222.6328195067848 5.9507e-05 deg
M 45.55540839507852 2.6528e-05 deg
tp 2456743.380615948367
(2014-Mar-26.88061595)
0.00017484 TDB
period 3027.587351702638
8.29
0.00052348
1.433e-06
d
yr
n .1189065609610059 2.0559e-08 deg/d
Q 5.135608107138126 5.9198e-07 au

Additional Model Parameters
 Parameter Value Uncertainty (1-sigma) 
A1 [EST] 5.4051073269441E-8 1.356E-8
A2 [EST] 1.477620841635678E-8 4.767E-9
  Orbit Determination Parameters
   # obs. used (total)      2883  
   data-arc span      3736 days (10.23 yr)  
   first obs. used      2010-11-03  
   last obs. used      2021-01-25  
   planetary ephem.      DE431  
   SB-pert. ephem.      SB431-N16  
   condition code      0  
   norm. resid. RMS      .62209  
   source      ORB  
   producer      Davide Farnocchia  
   solution date      2021-Feb-01 11:39:39  

Additional Information
 Earth MOID = 2.04627 au 
 Jupiter MOID = .258534 au 
 T_jup = 2.967 
[ 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
comet total magnitude M1 6.8   0.7 K222/16 2 parameter fit from 889 observations, autocmod 2.9a
comet total magnitude slope K1 13.   n/a K222/16 autocmod 2.9a
comet nuclear magnitude M2 11.4   0.5 K222/16 from 1832 observations, autocmod 2.9a
comet nuclear magnitude slope K2 5.   n/a K222/16 autocmod 2.9a
comet nuclear phase coefficient PC 0.03   n/a K222/16 autocmod 2.9a
diameter diameter 9 km n/a Scotti,J (1994) BAAS 26:1375  

117P/Helin-Roman-Alu 1          Discovered 1989-Oct-02 by Helin, Eleanor, Roman, Brian and Alu, Jeff at Palomar Mountain Observatory, California
Reference: comet.disLast Updated: 2003-08-29

[ show close-approach data ]
Alternate Designations
 Perihelion 
Year
(est.)
 New-Style 
Desig
Roman
 Numeral 
Year/
 Letter 
 1989.4   117P/1989 T2   1987 XXXVII   1989w 
Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances | Close-Approach Data ]
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