+ 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 2452749.5 (2003-Apr-20.0) TDB Reference: JPL 59 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .8350738462769237 5.3339e-08   a 7.72123378622071 6.629e-08 au q 1.273433390358047 4.1229e-07 au i 95.69806814972893 2.316e-05 deg node 1.415670065293847 4.2944e-05 deg peri 47.13845022529085 3.5656e-05 deg M 323.5772227049488 2.6451e-06 deg tp 2453542.364618675136 (2005-Jun-20.86461868) 5.816e-05 TDB period 7836.614446252856 21.46 0.00010092 2.763e-07 d yr n .045938204880315 5.916e-10 deg/d Q 14.16903418208337 1.2165e-07 au   Orbit Determination Parameters    # obs. used (total)      321      data-arc span      7958 days (21.79 yr)      first obs. used      1983-12-29      last obs. used      2005-10-12      planetary ephem.      DE431      SB-pert. ephem.      SB431-BIG16      condition code      0      norm. resid. RMS      .93788      source      ORB      producer      Otto Matic      solution date      2014-Jun-13 19:41:43   Additional Information  Earth MOID = .447763 au   Jupiter MOID = .122837 au   T_jup = 0.541  [ 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 11.4   2. 59 2 parameter fit from 30 observations, autocmod 2.5c comet total magnitude slope K1 12.   n/a 59 autocmod 2.5c comet nuclear magnitude M2 15.0   0.6 59 from 184 observations, autocmod 2.5c comet nuclear magnitude slope K2 5.   n/a 59 autocmod 2.5c comet nuclear phase coefficient PC 0.03   n/a 59 autocmod 2.5c [ 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-Feb-25 16:46 UT (server date/time)   Site Manager:   Ryan S. Park Webmaster:   Alan B. Chamberlin