+ View the NASA Portal + Center for Near-Earth Object Studies JPL Small-Body Database Browser Search: [ help ]   161P/Hartley-IRAS Classification: Halley-type Comet* [NEO]          SPK-ID: 1000042 [ Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Close-Approach Data ] [ show orbit diagram ] Orbital Elements at Epoch 2453190.5 (2004-Jul-04.0) TDB Reference: JPL 60 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .8350880971909477 5.3611e-08   a 7.730366119265318 8.797e-08 au q 1.274829386138673 4.1323e-07 au i 95.69805019936666 2.3761e-05 deg node 1.398165371226708 4.3147e-05 deg peri 47.09145237546669 3.6063e-05 deg M 343.8652517154134 2.6896e-06 deg tp 2453542.350534576275 (2005-Jun-20.85053458) 5.904e-05 TDB period 7850.52175672687 21.49 0.00013401 3.669e-07 d yr n .04585682469977579 7.8276e-10 deg/d Q 14.18590285239196 1.6143e-07 au   Orbit Determination Parameters    # obs. used (total)      335      data-arc span      7994 days (21.89 yr)      first obs. used      1983-11-23      last obs. used      2005-10-12      planetary ephem.      DE441      SB-pert. ephem.      SB441-N16      condition code      0      norm. resid. RMS      .8739      source      ORB      producer      Otto Matic      solution date      2021-Apr-15 23:27:43   Additional Information  Earth MOID = .448405 au   Jupiter MOID = .114876 au   T_jup = 0.540  [ show covariance matrix ] [ Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Close-Approach Data ] Physical Parameter Table Parameter Symbol Value Units Sigma Reference Notes comet total magnitude M1 11.5   2. 60 2 parameter fit from 30 observations, autocmod 2.9c comet total magnitude slope K1 11.5   n/a 60 autocmod 2.9c comet nuclear magnitude M2 15.0   0.6 60 from 184 observations, autocmod 2.9c comet nuclear magnitude slope K2 5.   n/a 60 autocmod 2.9c comet nuclear phase coefficient PC 0.03   n/a 60 autocmod 2.9c [ show close-approach data ] Alternate Designations  Perihelion  Year (est.)  New-Style  Desig Roman  Numeral  Year/  Letter   2005.5   161P/2004 V2         1984.0   161P/1983 V1   1984 III   1983v  [ Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Close-Approach Data ] 2021-Apr-20 19:16 UT (server date/time)   Site Manager:   Ryan S. Park Webmaster:   Alan B. Chamberlin