+ View the NASA Portal + Center for Near-Earth Object Studies JPL Small-Body Database Browser Search: [ help ]   1872 Helenos (1971 FG) Classification: Jupiter Trojan          SPK-ID: 2001872 [ Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances ] [ show orbit diagram ] Orbital Elements at Epoch 2459000.5 (2020-May-31.0) TDB Reference: JPL 24 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .04876737650201792 4.2913e-08   a 5.321020933392627 8.8152e-08 au q 5.06152870215875 2.8868e-07 au i 14.64024707204568 4.7561e-06 deg node 188.7879632170396 1.5204e-05 deg peri 114.4766716934488 5.489e-05 deg M 293.156924978106 5.3815e-05 deg tp 2459832.924393028952 (2022-Sep-10.42439303) 0.00067556 TDB period 4483.228537769499 12.27 0.00011141 3.05e-07 d yr n .0802992747229227 1.9954e-09 deg/d Q 5.580513164626504 9.2451e-08 au   Orbit Determination Parameters    # obs. used (total)      1858      data-arc span      24000 days (65.71 yr)      first obs. used      1954-12-22      last obs. used      2020-09-06      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      0      norm. resid. RMS      .46503      source      ORB      producer      Otto Matic      solution date      2020-Nov-13 04:14:43   Additional Information  Earth MOID = 4.07874 au   Jupiter MOID = .0665005 au   T_jup = 2.932  [ show covariance matrix ] [ Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances ] Physical Parameter Table Parameter Symbol Value Units Sigma Reference Notes absolute magnitude H 10.8   n/a MPO473789   diameter diameter 34.046 km 0.603 urn:nasa:pds:neowise_diameters_albedos::2.0[jupiter_trojans] (http://adsabs.harvard.edu/abs/2012ApJ...759...49G)   geometric albedo albedo 0.067   0.012 urn:nasa:pds:neowise_diameters_albedos::2.0[jupiter_trojans] (http://adsabs.harvard.edu/abs/2012ApJ...759...49G)   1872 Helenos (1971 FG)          Discovered 1971-Mar-24 by Van Houten, C. J. at Palomar Discovered by C. J. van Houten and I. van Houten-Groeneveld, Leiden, on plates exposed by T. Gehrels in a survey of faint Trojans with the 122 cm Schmidt camera at Palomar. Reference: DISCOVERY.DB Last Updated: 2003-08-29 [ Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances ] 2021-Jan-22 11:16 UT (server date/time)   Site Manager:   Ryan S. Park Webmaster:   Alan B. Chamberlin