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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 2457196.5 (2015-Jun-23.0) TDB
Reference: JPL K222/18 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .2539225524277177 1.1398e-07  
a 4.095628972254243 3.3239e-07 au
q 3.055656409822535 6.872e-07 au
i 8.697456101424551 6.5577e-06 deg
node 58.8820665390657 4.4347e-05 deg
peri 222.6229481904272 5.4324e-05 deg
M 53.88599015936855 2.1675e-05 deg
tp 2456743.338815476521
(2014-Mar-26.83881548)
0.00014987 TDB
period 3027.466433222615
8.29
0.00036855
1.009e-06
d
yr
n .118911310146813 1.4476e-08 deg/d
Q 5.135601534685951 4.1679e-07 au

Additional Model Parameters
 Parameter Value Uncertainty (1-sigma) 
A1 [EST] 7.094782444158679E-8 1.201E-8
A2 [EST] 1.841175238669423E-8 4.572E-9
  Orbit Determination Parameters
   # obs. used (total)      2973  
   data-arc span      3794 days (10.39 yr)  
   first obs. used      2010-11-03  
   last obs. used      2021-03-24  
   planetary ephem.      DE431  
   SB-pert. ephem.      SB431-N16  
   condition code      0  
   norm. resid. RMS      .61763  
   source      ORB  
   producer      Davide Farnocchia  
   solution date      2021-Mar-29 10:01:17  

Additional Information
 Earth MOID = 2.04678 au 
 Jupiter MOID = .258717 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 K222/18 2 parameter fit from 967 observations, autocmod 2.9c
comet total magnitude slope K1 13.   n/a K222/18 autocmod 2.9c
comet nuclear magnitude M2 11.4   0.5 K222/18 from 1839 observations, autocmod 2.9c
comet nuclear magnitude slope K2 5.   n/a K222/18 autocmod 2.9c
comet nuclear phase coefficient PC 0.03   n/a K222/18 autocmod 2.9c
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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