+ View the NASA Portal + Center for Near-Earth Object Studies JPL Small-Body Database Browser Search: [ help ]   2684 Douglas (1981 AH1) Classification: Main-belt Asteroid          SPK-ID: 2002684 [ 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 40 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .0477489798427727 3.3475e-08   a 3.052571099312674 1.6032e-08 au q 2.906813943422963 1.0623e-07 au i 9.932901862490247 4.1562e-06 deg node 150.6704050376607 2.3256e-05 deg peri 111.379107752379 5.2663e-05 deg M 48.35314212847208 4.6666e-05 deg tp 2458938.850861340020 (2020-Mar-30.35086134) 0.0002527 TDB period 1948.036586067652 5.33 1.5347e-05 4.202e-08 d yr n .1848014573107704 1.4559e-09 deg/d Q 3.198328255202385 1.6798e-08 au   Orbit Determination Parameters    # obs. used (total)      2426      data-arc span      22196 days (60.77 yr)      first obs. used      1960-02-27      last obs. used      2020-12-04      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      0      norm. resid. RMS      .42762      source      ORB      producer      Otto Matic      solution date      2021-Feb-24 01:04:49   Additional Information  Earth MOID = 1.90774 au   Jupiter MOID = 1.88873 au   T_jup = 3.212  [ 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 11.68   n/a E2021B10   diameter diameter 15.962 km 0.255 urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (http://adsabs.harvard.edu/abs/2011ApJ...741...68M)   geometric albedo albedo 0.159   0.008 urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (http://adsabs.harvard.edu/abs/2011ApJ...741...68M)   2684 Douglas (1981 AH1)          Discovered 1981-Jan-03 by Thomas, N. G. at Flagstaff (AM) Discovered at the Anderson Mesa station, which is operated by the Lowell Observatory. Reference: DISCOVERY.DB Last Updated: 2003-08-29 [ show close-approach data ] Alternate Designations  1981 AH1 = 1960 DE = 1972 NY = 1978 PO2 = 1978 RU4 = 1978 SE4  [ Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances | Close-Approach Data ] 2021-Feb-28 21:38 UT (server date/time)   Site Manager:   Ryan S. Park Webmaster:   Alan B. Chamberlin