+ 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 2459200.5 (2020-Dec-17.0) TDB Reference: JPL 25 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .04903770691881038 4.2708e-08   a 5.321153693867414 8.7419e-08 au q 5.060216518557598 2.8722e-07 au i 14.64015044110235 4.7371e-06 deg node 188.7871740341844 1.4997e-05 deg peri 114.6330107860831 5.4302e-05 deg M 309.0948175447888 5.3341e-05 deg tp 2459834.466966496171 (2022-Sep-11.96696650) 0.00066828 TDB period 4483.396324911077 12.27 0.00011048 3.025e-07 d yr n .08029626959359658 1.9787e-09 deg/d Q 5.58209086917723 9.1706e-08 au   Orbit Determination Parameters    # obs. used (total)      1914      data-arc span      24182 days (66.21 yr)      first obs. used      1954-12-22      last obs. used      2021-03-07      planetary ephem.      DE441      SB-pert. ephem.      SB441-N16      condition code      0      norm. resid. RMS      .46309      source      ORB      producer      Otto Matic      solution date      2021-Apr-12 13:03:25   Additional Information  Earth MOID = 4.07545 au   Jupiter MOID = .0664304 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 10.88   n/a E2021B10   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-Jun-22 08:50 UT (server date/time)   Site Manager:   Ryan S. Park Webmaster:   Alan B. Chamberlin