+ 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 2459200.5 (2020-Dec-17.0) TDB Reference: JPL 32 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .2373136319102141 3.6572e-08   a 2.347372022775341 7.3952e-09 au q 1.790308642606099 8.4774e-08 au i 23.38298749309499 4.3054e-06 deg node 105.3068708523852 1.0007e-05 deg peri 54.42360048243458 1.3162e-05 deg M 221.8959070930752 1.0474e-05 deg tp 2459704.435973942347 (2022-May-04.93597394) 3.9584e-05 TDB period 1313.624721763394 3.60 6.2077e-06 1.7e-08 d yr n .274050871634587 1.2951e-09 deg/d Q 2.904435402944583 9.1502e-09 au   Orbit Determination Parameters    # obs. used (total)      1954      data-arc span      32513 days (89.02 yr)      first obs. used      1932-01-10      last obs. used      2021-01-15      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      0      norm. resid. RMS      .38026      source      ORB      producer      Otto Matic      solution date      2021-Feb-24 00:57:09   Additional Information  Earth MOID = .877538 au   Jupiter MOID = 2.34313 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-Mar-05 14:08 UT (server date/time)   Site Manager:   Ryan S. Park Webmaster:   Alan B. Chamberlin