+ View the NASA Portal + Center for Near-Earth Object Studies JPL Small-Body Database Browser Search: [ help ]   869 Mellena (A917 JB) Classification: Main-belt Asteroid          SPK-ID: 2000869 [ 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 42 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .2201975269245558 3.1996e-08   a 2.688675804059924 8.1351e-09 au q 2.096636041304037 8.5736e-08 au i 7.838532971105057 3.971e-06 deg node 154.8793579848599 2.7316e-05 deg peri 107.0905053300259 2.8699e-05 deg M 90.37592689203599 9.7862e-06 deg tp 2458596.244116898949 (2019-Apr-22.74411690) 4.312e-05 TDB period 1610.297375873474 4.41 7.3084e-06 2.001e-08 d yr n .2235611914878301 1.0146e-09 deg/d Q 3.280715566815811 9.9265e-09 au   Orbit Determination Parameters    # obs. used (total)      2851      data-arc span      37811 days (103.52 yr)      first obs. used      1917-05-10      last obs. used      2020-11-16      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      0      norm. resid. RMS      .41909      source      ORB      producer      Otto Matic      solution date      2020-Dec-18 01:56:49   Additional Information  Earth MOID = 1.09745 au   Jupiter MOID = 1.86884 au   T_jup = 3.325  [ 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 11.9   n/a MPO448919   diameter diameter 21.193 km 0.090 urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (http://adsabs.harvard.edu/abs/2014ApJ...791..121M)   rotation period rot_per 6.5155 h n/a LCDB (Rev. 2020-October); Warner et al., 2009 Published Reference List: [Stephens, R.D. (2010) Minor Planet Bull. 37, 159-161.] [Carbognani, A. (2011) Minor Planet Bull. 38, 57-63.] [Ferrero, A. (2011) Entry on CALL web site. http://www.minorplanet.info/call.html] [Owings, L.E. (2011) Minor Planet Bull. 38, 9-10.] [Franco, L.; Marchini, A.; Arena, C.; Casalnuovo, G.B.; et al. (2020) Minor Planet Bull. 47, 61-63.] geometric albedo albedo 0.065   0.009 urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (http://adsabs.harvard.edu/abs/2012ApJ...759L...8M)   869 Mellena (A917 JB)          Discovered 1917-May-09 by Schorr, R. at Bergedorf Independent discovery May 10 by M. Wolf, Heidelberg, was announced first. Reference: DISCOVERY.DB Last Updated: 2003-08-29 [ show close-approach data ] Alternate Designations  A917 JB = 1931 RC = 1944 OB = 1952 DL2  [ Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances | Close-Approach Data ] 2021-Jan-21 06:45 UT (server date/time)   Site Manager:   Ryan S. Park Webmaster:   Alan B. Chamberlin