+ View the NASA Portal + Near-Earth Object (NEO) Program Search JPL JPL Small-Body Database Browser Search: [ help ]   21P/Giacobini-Zinner Classification: Jupiter-family Comet [NEO]          SPK-ID: 1000032 [ Ephemeris | Orbit Diagram | Orbital Elements | Physical Parameters | Discovery Circumstances | Close-Approach Data ] [ show orbit diagram ] alternate orbits: [epoch=2013-03-13.0] K123/5 (default) [epoch=2006-03-09.0] K054/18 [epoch=1998-11-03.0] SAO/1998 [epoch=1992-04-08.0] SAO/1992 [epoch=1985-09-12.0] SAO/1985 [epoch=1979-02-16.0] SAO/1979 [epoch=1972-07-22.0] SAO/1972 [epoch=1966-03-16.0] SAO/1966 [epoch=1959-11-08.0] SAO/1959 [epoch=1946-09-17.0] SAO/1946 [epoch=1940-02-21.0] SAO/1940 [epoch=1933-07-27.0] SAO/1933 [epoch=1926-12-31.0] SAO/1926 [epoch=1913-11-09.0] SAO/1913 [epoch=1900-12-07.0] SAO/1900 Orbital Elements at Epoch 2456364.5 (2013-Mar-13.0) TDB Reference: JPL K123/5 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .7068959571305257 1.2944e-07   a 3.515852288498695 1.1487e-07 AU q 1.030510519890861 4.4882e-07 AU i 31.90986189089459 1.705e-05 deg node 195.3941516560791 3.3588e-05 deg peri 172.5883270219408 4.3809e-05 deg M 59.10203345619887 8.7096e-06 deg tp 2455969.184101620009 (2012-Feb-11.68410162) 4.5401e-05 JED period 2407.932774804896 6.59 0.00011801 3.231e-07 d yr n .1495058349497191 7.3269e-09 deg/d Q 6.00119405710653 1.9607e-07 AU Additional Model Parameters  Parameter Value Uncertainty (1-sigma)  A1 [EST] 3.260103128285035E-9 4.769E-11 A2 [EST] -4.586780336285469E-10 1.581E-11 A3 [EST] -9.557319222111897E-10 4.469E-11 DT [EST] -31.9058825479079 .6752   Orbit Determination Parameters    # obs. used (total)      1532      data-arc span      5503 days (15.07 yr)      first obs. used      1998-01-20      last obs. used      2013-02-13      planetary ephem.      DE405      SB-pert. ephem.      SB405-CPV-2      condition code      0      fit RMS      .77528      data source      ORB      producer      Ryan S. Park      solution date      2013-Mar-03 19:22:30   Additional Information  Earth MOID = .0331829 AU   T_jup = 2.467  [ 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 10.5 mag 1. K123/5 2 parameter fit from 470 observations, autocmod 2.5b comet total magnitude slope K1 15.   n/a K123/5 autocmod 2.5b diameter diameter 2.0 km n/a Lamy,P.L.,Toth,I.,Fernandez,Y.R.,Weaver,H.A. (2004) Comets II, pp. 223-264   21P/Giacobini-Zinner          Discovered 1900-Dec-20 by Giacobini, M. at Nice Observatory, France Reference: comet.dis Last Updated: 2003-08-29 [ show close-approach data ] Alternate Designations  Perihelion  Year (est.)  New-Style  Desig Roman  Numeral  Year/  Letter   1992.3       1992 IX   1991m   1985.7       1985 XIII   1984e   1979.2       1979 III   1978h   1972.6       1972 VI   1972d   1966.0       1966 I   1965g   1959.4       1959 VIII   1959b   1946.2       1946 V   1946c   1939.6       1940 I   1939l   1933.0       1933 III   1933c   1926.4       1926 VI   1926e   1913.2   21P/1913 U1   1913 V   1913e   1900.0   21P/1900 Y1   1900 III   1900c  [ Ephemeris | Orbit Diagram | Orbital Elements | Physical Parameters | Discovery Circumstances | Close-Approach Data ] 2013-May-24 12:32 UT (server date/time)   Site Manager:   Donald K. Yeomans Webmaster:   Alan B. Chamberlin