+ View the NASA Portal + Near-Earth Object (NEO) Program Search JPL JPL Small-Body Database Browser Search: [ help ]   78P/Gehrels 2 Classification: Jupiter-family Comet          SPK-ID: 1000030 [ Ephemeris | Orbit Diagram | Orbital Elements | Physical Parameters | Discovery Circumstances | Close-Approach Data ] [ show orbit diagram ] alternate orbits: [epoch=2013-03-13.0] K114/6 (default) [epoch=2006-03-09.0] K043/41 [epoch=1989-11-10.0] J974/3 [epoch=1981-11-12.0] SAO/1981 [epoch=1973-11-14.0] SAO/1973 Orbital Elements at Epoch 2456364.5 (2013-Mar-13.0) TDB Reference: JPL K114/6 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .4623087433270055 9.6757e-08   a 3.735418990461866 9.2018e-08 AU q 2.008502131181609 3.9469e-07 AU i 6.255121569087698 1.0983e-05 deg node 210.5547915095289 2.5121e-05 deg peri 192.7396504535754 4.1566e-05 deg M 58.05999968979462 1.351e-05 deg tp 2455939.213165261387 (2012-Jan-12.71316526) 8.9418e-05 JED period 2636.983488183037 7.22 9.7439e-05 2.668e-07 d yr n .136519626161198 5.0445e-09 deg/d Q 5.462335849742121 1.3456e-07 AU Additional Model Parameters  Parameter Value Uncertainty (1-sigma)  A1 [EST] 8.140741260497563E-9 5.088E-11 A2 [EST] -2.907705647869254E-10 4.205E-11 A3 [EST] -5.202118052475708E-10 1.047E-10 DT [EST] -64.23045561897675 2.672   Orbit Determination Parameters    # obs. used (total)      5420      data-arc span      14398 days (39.42 yr)      first obs. used      1973-09-29      last obs. used      2013-03-01      planetary ephem.      DE405      SB-pert. ephem.      SB405-CPV-2      condition code      0      fit RMS      .62222      data source      ORB      producer      Ryan S. Park      solution date      2013-Mar-03 19:25:29   Additional Information  Earth MOID = 1.01593 AU   T_jup = 2.887  [ show covariance matrix ] [ Ephemeris | Orbit Diagram | Orbital Elements | Physical Parameters | Discovery Circumstances | Close-Approach Data ] Physical Parameter Table Parameter Symbol Value Units Sigma Reference Notes comet total magnitude M1 6.5 mag n/a ICQ 2005 Handbook   comet total magnitude slope K1 14.0   n/a ICQ 2005 Handbook   78P/Gehrels 2          Discovered 1973-Sep-29 by Gehrels, Tom discovered on plate/photo taken on discovery date as well as 9/30, 10/4 Reference: comet.dis Last Updated: 2003-08-29 [ show close-approach data ] Alternate Designations  Perihelion  Year (est.)  New-Style  Desig Roman  Numeral  Year/  Letter   1990.4       1989 XVII   1989n   1983.2   78P/1981 L1   1981 XVII   1981f   1975.9   78P/1973 S1   1973 XI   1973n  [ Ephemeris | Orbit Diagram | Orbital Elements | Physical Parameters | Discovery Circumstances | Close-Approach Data ] 2013-May-25 06:26 UT (server date/time)   Site Manager:   Donald K. Yeomans Webmaster:   Alan B. Chamberlin