+ View the NASA Portal + Center for Near-Earth Object Studies JPL Small-Body Database Browser Search: [ help ]   21071 (1991 PE7) Classification: Main-belt Asteroid          SPK-ID: 2021071 [ Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances | Close-Approach Data ] [ show orbit diagram ] Orbital Elements at Epoch 2459200.5 (2020-Dec-17.0) TDB Reference: JPL 35 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .05905252165793944 1.7502e-08   a 2.554222889583063 1.1238e-08 au q 2.403389587076755 4.0864e-08 au i 14.61446767580203 3.9175e-07 deg node 330.2794694821018 3.185e-06 deg peri 296.3156147547839 1.8383e-05 deg M 117.110433037918 1.6912e-05 deg tp 2458715.457602704899 (2019-Aug-19.95760270) 6.984e-05 TDB period 1491.030803119818 4.08 9.8399e-06 2.694e-08 d yr n .2414437040782388 1.5934e-09 deg/d Q 2.705056192089371 1.1901e-08 au   Orbit Determination Parameters    # obs. used (total)      2064      data-arc span      10805 days (29.58 yr)      first obs. used      1991-08-06      last obs. used      2021-03-06      planetary ephem.      DE441      SB-pert. ephem.      SB441-N16      condition code      0      norm. resid. RMS      .47282      source      ORB      producer      Otto Matic      solution date      2021-Apr-13 03:38:27   Additional Information  Earth MOID = 1.41967 au   Jupiter MOID = 2.46153 au   T_jup = 3.391  [ show covariance matrix ] [ Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances | Close-Approach Data ] Physical Parameter Table Parameter Symbol Value Units Sigma Reference Notes absolute magnitude H 13.92   n/a E2021B10   diameter diameter 4.468 km 0.150 urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (http://adsabs.harvard.edu/abs/2011ApJ...741...68M)   geometric albedo albedo 0.185   0.024 urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (http://adsabs.harvard.edu/abs/2011ApJ...741...68M)   21071 (1991 PE7)          Discovered 1991-Aug-06 by Elst, E. W. at La Silla Reference: 20010208/Numbers.arc Last Updated: 2004-04-19 [ show close-approach data ] Alternate Designations  1991 PE7 = 2000 XB36  [ Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances | Close-Approach Data ] 2021-Apr-13 20:42 UT (server date/time)   Site Manager:   Ryan S. Park Webmaster:   Alan B. Chamberlin