+ View the NASA Portal + Center for Near-Earth Object Studies JPL Small-Body Database Browser Search: [ help ]   18499 Showalter (1996 MR) Classification: Mars-crossing Asteroid          SPK-ID: 2018499 [ 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 17 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .3497658340089857 3.8152e-08   a 2.391783388308791 1.0222e-08 au q 1.555219276728129 9.1887e-08 au i 4.285570272613377 4.4408e-06 deg node 134.6097325242467 5.6352e-05 deg peri 193.3703395430431 5.6923e-05 deg M 212.1150657323898 1.3161e-05 deg tp 2459755.512323882456 (2022-Jun-25.01232388) 5.2483e-05 TDB period 1351.080403066084 3.70 8.6611e-06 2.371e-08 d yr n .2664534243728437 1.7081e-09 deg/d Q 3.228347499889453 1.3797e-08 au   Orbit Determination Parameters    # obs. used (total)      683      data-arc span      9517 days (26.06 yr)      first obs. used      1995-03-01      last obs. used      2021-03-21      planetary ephem.      DE441      SB-pert. ephem.      SB441-N16      condition code      0      norm. resid. RMS      .57606      source      ORB      producer      Otto Matic      solution date      2021-May-04 02:44:14   Additional Information  Earth MOID = .542265 au   Jupiter MOID = 2.14018 au   T_jup = 3.442  [ hide covariance matrix ] Orbital Elements at Epoch 2457136.5 (2015-Apr-24.0) TDB Reference: JPL 17 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .351159741585894 3.8179e-08   q 1.551016835188462 9.2004e-08 au tp 2457053.462567823172 (2015-Jan-30.96256782) 3.7969e-05 TDB node 134.6858274894691 5.6301e-05 deg peri 193.2854031818549 5.6866e-05 deg i 4.288329109443795 4.4458e-06 deg   Orbit Determination Parameters    # obs. used (total)      683      data-arc span      9517 days (26.06 yr)      first obs. used      1995-03-01      last obs. used      2021-03-21      planetary ephem.      DE441      SB-pert. ephem.      SB441-N16      condition code      0      norm. resid. RMS      .57606      source      ORB      producer      Otto Matic      solution date      2021-May-04 02:44:14   Additional Information  Jupiter MOID = 2.14018 au   T_jup = 3.442  Orbit Covariance (6×6)   e q tp node peri i e 1.457609757095657E-15 -3.503588363129358E-15 -1.539777427990758E-13 7.4473042724597E-15 -1.925853336953045E-14 8.475083534863049E-16 q -3.503588363129358E-15 8.464659006172791E-15 5.562217257435856E-13 -1.840785243418529E-14 8.336033544170821E-14 -1.741986384068195E-15 tp -1.539777427990758E-13 5.562217257435856E-13 1.441626738844661E-9 -1.834798024101366E-11 3.225641712378952E-10 2.006793110084129E-12 node 7.4473042724597E-15 -1.840785243418529E-14 -1.834798024101366E-11 3.169854525881417E-9 -3.164298265780606E-9 1.686984465842848E-11 peri -1.925853336953045E-14 8.336033544170821E-14 3.225641712378952E-10 -3.164298265780606E-9 3.233724838585899E-9 -1.64063308793138E-11 i 8.475083534863049E-16 -1.741986384068195E-15 2.006793110084129E-12 1.686984465842848E-11 -1.64063308793138E-11 1.976536914952218E-11 [ Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances ] Physical Parameter Table Parameter Symbol Value Units Sigma Reference Notes absolute magnitude H 15.86   n/a MPCxxxxx   18499 Showalter           Discovered 1996 June 22 by NEAT at Haleakala. Mark R. Showalter (b. 1957), planetary scientist at the SETI Institute, is (co-)discover of the Jovian gossamer ring, Saturnian moon Pan, Uranian moons Mab and Cupid, two faint Uranian rings, Neptunian moon S/2004 N 1, and Plutonian moons Kerberos and Styx. He is the leader of the Planetary Data Systems Rings Node. NOTE: some special characters may not display properly (any characters within {} are an attempt to place the proper accent above a character) Reference: MPC batch dated 2014-09-09 Last Updated: 2014-11-10 Alternate Designations  1996 MR = 1995 FW6  [ Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances ] 2021-May-12 03:16 UT (server date/time)   Site Manager:   Ryan S. Park Webmaster:   Alan B. Chamberlin