+ 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 2459000.5 (2020-May-31.0) TDB Reference: JPL 39 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .04715343564257046 3.3655e-08   a 3.052064070221236 1.5248e-08 au q 2.908148763509057 1.0619e-07 au i 9.922757718221025 4.1527e-06 deg node 150.7127451069952 2.3311e-05 deg peri 112.1663507940754 5.3126e-05 deg M 10.65813344901046 4.7154e-05 deg tp 2458942.840941159580 (2020-Apr-03.34094116) 0.00025516 TDB period 1947.551255748102 5.33 1.4595e-05 3.996e-08 d yr n .1848475098858003 1.3852e-09 deg/d Q 3.195979376933415 1.5967e-08 au   Orbit Determination Parameters    # obs. used (total)      2422      data-arc span      22172 days (60.70 yr)      first obs. used      1960-02-27      last obs. used      2020-11-10      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      0      norm. resid. RMS      .42776      source      ORB      producer      Otto Matic      solution date      2020-Dec-18 02:07:45   Additional Information  Earth MOID = 1.91046 au   Jupiter MOID = 1.89266 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 11.6   n/a MPO337270   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-Jan-21 18:51 UT (server date/time)   Site Manager:   Ryan S. Park Webmaster:   Alan B. Chamberlin