+ 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 22 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .04876737751174502 4.3007e-08   a 5.321020937774681 8.8594e-08 au q 5.061528700954324 2.8877e-07 au i 14.64024695604115 4.8497e-06 deg node 188.7879636693374 1.5338e-05 deg peri 114.4766747895529 5.5381e-05 deg M 293.1569210298518 5.4421e-05 deg tp 2459832.924443226488 (2022-Sep-10.42444323) 0.00068335 TDB period 4483.22854330765 12.27 0.00011197 3.066e-07 d yr n .08029927462372866 2.0055e-09 deg/d Q 5.580513174595038 9.2915e-08 au   Orbit Determination Parameters    # obs. used (total)      1756      data-arc span      23920 days (65.49 yr)      first obs. used      1954-12-22      last obs. used      2020-06-18      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      0      norm. resid. RMS      .4698      source      ORB      producer      Otto Matic      solution date      2020-Jun-23 15:37:47   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 ] 2020-Jul-02 20:16 UT (server date/time)   Site Manager:   Ryan S. Park Webmaster:   Alan B. Chamberlin