+ View the NASA Portal + Center for Near-Earth Object Studies JPL Small-Body Database Browser Search: [ help ]   19727 Allen (1999 XS2) Classification: Main-belt Asteroid          SPK-ID: 2019727 [ Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances ] [ show orbit diagram ] Orbital Elements at Epoch 2459396.5 (2021-Jul-01.0) TDB Reference: JPL 37 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .1871768891532357 2.2393e-08   a 2.435053822861149 9.424e-09 au q 1.979268023377305 5.7149e-08 au i 13.35625234567705 7.1608e-07 deg node 253.1298131173909 3.9453e-06 deg peri 325.0661691291875 8.9188e-06 deg M 66.26242127435677 1.047e-05 deg tp 2459141.038137075770 (2020-Oct-18.53813708) 3.98e-05 TDB period 1387.909902536465 3.80 8.0571e-06 2.206e-08 d yr n .2593828312213096 1.5058e-09 deg/d Q 2.890839622344993 1.1188e-08 au   Orbit Determination Parameters    # obs. used (total)      2176      data-arc span      12948 days (35.45 yr)      first obs. used      1986-01-10      last obs. used      2021-06-23      planetary ephem.      DE441      SB-pert. ephem.      SB441-N16      condition code      0      norm. resid. RMS      .40636      source      ORB      producer      Otto Matic      solution date      2021-Jul-08 04:52:24   Additional Information  Earth MOID = .984456 au   Jupiter MOID = 2.15743 au   T_jup = 3.445  [ 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 13.2   n/a MPO502317   diameter diameter 5.949 km 0.091 urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (http://adsabs.harvard.edu/abs/2011ApJ...741...68M)   geometric albedo albedo 0.262   0.048 urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (http://adsabs.harvard.edu/abs/2011ApJ...741...68M)   19727 Allen           Discovered 1999 Dec. 4 by C. W. Juels at Fountain Hills. London-based solar physicist Clabon Walter Allen (1904-1987) authored the first (1955) through third (1973) editions of Astrophysical Quantities, without which most professional astronomers would never have received their degrees, and most watchers of the sky would never have successfully completed their observing sessions. NOTE: some special characters may not display properly (any characters within {} are an attempt to place the proper accent above a character) Reference: 20060613/MPCPages.arc Last Updated: 2008-05-22 Alternate Designations  1999 XS2 = 1994 LK4  [ Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances ] 2021-Jul-25 01:11 UT (server date/time)   Site Manager:   Ryan S. Park Webmaster:   Alan B. Chamberlin