+ View the NASA Portal + Center for Near-Earth Object Studies JPL Small-Body Database Browser Search: [ help ]   11887 Echemmon (1990 TV12) Classification: Jupiter Trojan          SPK-ID: 2011887 [ 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 23 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .09187469245077408 5.5931e-08   a 5.181942047078476 1.0204e-07 au q 4.705852715205407 3.1186e-07 au i 24.0446890531129 6.6571e-06 deg node 242.6496936690129 1.341e-05 deg peri 111.4664983229217 3.8643e-05 deg M 239.0886466882509 3.9718e-05 deg tp 2460447.610969853748 (2024-May-17.11096985) 0.00050315 TDB period 4308.610687733713 11.80 0.00012727 3.484e-07 d yr n .08355361532776508 2.468e-09 deg/d Q 5.658031378951546 1.1142e-07 au   Orbit Determination Parameters    # obs. used (total)      1213      data-arc span      23948 days (65.57 yr)      first obs. used      1954-11-23      last obs. used      2020-06-17      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      0      norm. resid. RMS      .489      source      ORB      producer      Otto Matic      solution date      2020-Jun-23 17:21:10   Additional Information  Earth MOID = 3.7889 au   Jupiter MOID = .0571126 au   T_jup = 2.819  [ 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 MPO324419   diameter diameter 31.190 km 0.494 urn:nasa:pds:neowise_diameters_albedos::2.0[jupiter_trojans] (http://adsabs.harvard.edu/abs/2012ApJ...759...49G)   rotation period rot_per 8.47 h n/a LCDB (Rev. 2019-August); Warner et al., 2009 Result based on less than full coverage, so that the period may be wrong by 30 percent or so. Published Reference List: [Stephens, R.D.; French, L.M.; Davitt, C.; Coley, D.R. (2014) Minor Planet Bull. 41, 95-100.] geometric albedo albedo 0.095   0.008 urn:nasa:pds:neowise_diameters_albedos::2.0[jupiter_trojans] (http://adsabs.harvard.edu/abs/2012ApJ...759...49G)   11887 Echemmon           Discovered 1990 Oct. 14 by F. Borngen and L. D. Schmadel at Tautenburg. The hero Echemmon, son of the king of Troy Priamos, was killed together with his brother Chromios by Diomedes, king of Argos. The name was suggested by the first discoverer. NOTE: some special characters may not display properly (any characters within {} are an attempt to place the proper accent above a character) Reference: 20010309/MPCPages.arc Last Updated: 2009-05-11 Alternate Designations  1990 TV12 = 1989 SX13  [ Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances ] 2020-Jul-02 14:14 UT (server date/time)   Site Manager:   Ryan S. Park Webmaster:   Alan B. Chamberlin