+ View the NASA Portal + Center for Near-Earth Object Studies JPL Small-Body Database Browser Search: [ help ]   1657 Roemera (1961 EA) Classification: Main-belt Asteroid          SPK-ID: 2001657 [ 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 34 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .2374005837467185 1.1606e-08   a 2.347428968157123 6.8818e-09 au q 1.790147960812665 2.6583e-08 au i 23.38294570786422 6.8513e-07 deg node 105.3063496536401 1.3795e-06 deg peri 54.40867951442305 2.6918e-06 deg M 275.6381734142424 3.4493e-06 deg tp 2459704.343926668029 (2022-May-04.84392667) 1.3815e-05 TDB period 1313.672523292667 3.60 5.7768e-06 1.582e-08 d yr n .2740408995521005 1.2051e-09 deg/d Q 2.904709975501581 8.5155e-09 au   Orbit Determination Parameters    # obs. used (total)      1982      data-arc span      32513 days (89.02 yr)      first obs. used      1932-01-10      last obs. used      2021-01-15      planetary ephem.      DE441      SB-pert. ephem.      SB441-N16      condition code      0      norm. resid. RMS      .38058      source      ORB      producer      Otto Matic      solution date      2021-Apr-12 12:45:41   Additional Information  Earth MOID = .877981 au   Jupiter MOID = 2.34272 au   T_jup = 3.414  [ 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 12.82   n/a E2021B10   diameter diameter 7.665 km 0.219 urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (http://adsabs.harvard.edu/abs/2012ApJ...759L...8M)   rotation period rot_per 34.0 h n/a LCDB (Rev. 2020-October); Warner et al., 2009 Result based on less than full coverage, so that the period may be wrong by 30 percent or so. Published Reference List: [Warner, B.D. (2009) Minor Planet Bull. 36, 7-13.] geometric albedo albedo 0.220   0.030 urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (http://adsabs.harvard.edu/abs/2012ApJ...759L...8M)   Tholen spectral type spec_T S   n/a EAR-A-5-DDR-TAXONOMY-V4.0 used 7 color indices 1657 Roemera (1961 EA)          Discovered 1961-Mar-06 by Wild, P. at Zimmerwald Reference: DISCOVERY.DB Last Updated: 2003-08-29 Alternate Designations  1961 EA = 1932 AB  [ Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances ] 2021-Jul-29 17:02 UT (server date/time)   Site Manager:   Ryan S. Park Webmaster:   Alan B. Chamberlin