+ View the NASA Portal + Center for Near-Earth Object Studies JPL Small-Body Database Browser Search: [ help ]   498 Tokio (A902 XA) Classification: Main-belt Asteroid          SPK-ID: 2000498 [ 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 78 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .2227494338673068 3.3278e-08   a 2.652218234171536 7.359e-09 au q 2.061438124017279 8.8026e-08 au i 9.496873280033627 3.3809e-06 deg node 97.21168990746737 2.2989e-05 deg peri 241.7793981564314 2.4057e-05 deg M 137.4817312723214 8.9984e-06 deg tp 2458398.003118498532 (2018-Oct-06.50311850) 3.8481e-05 TDB period 1577.655993514505 4.32 6.5662e-06 1.798e-08 d yr n .2281866271734162 9.4971e-10 deg/d Q 3.242998344325794 8.9982e-09 au   Orbit Determination Parameters    # obs. used (total)      4268      data-arc span      42598 days (116.63 yr)      first obs. used      1904-03-14      last obs. used      2020-10-29      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      0      norm. resid. RMS      .38454      source      ORB      producer      Otto Matic      solution date      2020-Nov-13 04:28:57   Additional Information  Earth MOID = 1.07172 au   Jupiter MOID = 2.1947 au   T_jup = 3.335  [ 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 8.9   n/a MPO502157 IRAS observations used: 15 diameter diameter 81.83 km 2.3 IRAS-A-FPA-3-RDR-IMPS-V6.0 IRAS observations used: 15 rotation period rot_per 41.85 h n/a LCDB (Rev. 2019-August); Warner et al., 2009 Published Reference List: [Pilcher, F.; Martinez, L. (2013) Minor Planet Bull. 40, 196-197.] geometric albedo albedo 0.0694   0.004 IRAS-A-FPA-3-RDR-IMPS-V6.0 IRAS observations used: 15 B-V BV 0.780   0.024 EAR-A-5-DDR-UBV-MEAN-VALUES-V1.2 #obs=4; phase (min.=.73, mean=10.06, max.=21.97) deg. U-B UB 0.375   0.025 EAR-A-5-DDR-UBV-MEAN-VALUES-V1.2 #obs=4; phase (min.=.73, mean=10.06, max.=21.97) deg. Tholen spectral type spec_T M   n/a EAR-A-5-DDR-TAXONOMY-V4.0 used 7 color indices; used ground-based radiometric albedo 498 Tokio (A902 XA)          Discovered 1902-Dec-02 by Charlois, A. at Nice Reference: DISCOVERY.DB Last Updated: 2003-08-29 Alternate Designations  A902 XA = A900 EB  [ Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances ] 2020-Nov-26 08:27 UT (server date/time)   Site Manager:   Ryan S. Park Webmaster:   Alan B. Chamberlin