{"object":{"kind":"an","prefix":null,"pha":false,"neo":false,"des":"21","spkid":"20000021","shortname":"21 Lutetia","orbit_class":{"code":"MBA","name":"Main-belt Asteroid"},"orbit_id":"146","fullname":"21 Lutetia (A852 VA)"},"phys_par":[{"units":null,"name":"H","desc":"absolute magnitude (magnitude at 1 au from Sun and observer)","notes":"IRAS observations used: 15","value":"7.48","title":"absolute magnitude","sigma":null,"ref":"MPO980521"},{"title":"magnitude slope","sigma":null,"ref":"PDS3 (MPC 17257)","desc":"magnitude slope parameter used in the standard asteroid H/G magnitude law","name":"G","units":null,"notes":"Fit","value":"0.11"},{"value":"98","notes":null,"desc":"effective body diameter","name":"diameter","units":"km","sigma":"2","ref":"Sierks et al., Science 334, 487, 2011","title":"diameter"},{"ref":"Sierks et al., Science 334, 487, 2011","sigma":"1 x 1 x 13","title":"extent","notes":null,"value":"121 x 101 x 75","name":"extent","units":"km","desc":"tri(or bi)-axial body dimensions"},{"notes":null,"value":"0.1134","desc":"standard gravitational parameter: product of the mass (M) and gravitational constant (G)","units":"km^3/s^2","name":"GM","ref":"Patzold et al., Science 334, 491, 2011","sigma":"0.0011","title":"GM"},{"title":"bulk density","sigma":"0.3","ref":"Patzold et al., Science 334, 491, 2011","desc":"bulk density","units":"g/cm^3","name":"density","value":"3.4","notes":null},{"title":"rotation period","sigma":null,"ref":"LCDB (Rev. 2023-October); Warner et al., 2009","desc":"body rotation period (synodic)","name":"rot_per","units":"h","value":"8.1655","notes":"REFERENCE LIST:[Lupishko, D.F.; Bel'skaya, I.N.; Tupieva, F.A. (1983) Pis'ma Astron. Zh. 9, 691-694; Sov. Astron. Lett. 9, 358-360.], [Zappala, V.; Di Martino, M.; Knezevic, Z.; Djurasevic, G. (1984) Astron. Astrophys. 130, 208-210.], [Lupishko, D.F.; Velichko, F.P. (1987) Kin. Fiz. Neb. Tel 3(1), 57-65; Kinematics and Physics of Celestial Bodies 3(1), 63-71.], [Michalowski, T. (1992) in Asteroids, Comets, Meteors 1991. A.W. Harris, E. Bowell, eds. Lunar and Planetary Institute, Houston, pp. 417-419.], [Michalowski, T. (1993) Icarus 106, 563-572.], [De Angelis, G. (1995) Planet. Space Sci. 43, 649-682.], [Lagerkvist, C.-I.; Erikson, A.; Debehogne, H.; Festin, L.; et al. (1995) Astron. Astrophys. Suppl. Ser. 113, 115-129.], [Michalowski, T. (1996) Icarus 123, 456-462.], [Szabo, Gy.; Sarneczky, K.; Kiss, L.L. (1999) in Proc. IAU Coll. 173, Evolution and Source Regions of Asteroids and Comets, 185-188.], [Behrend, R. (2003) Observatoire de Geneve web site, http://obswww.unige.ch/~behrend/page_cou.html], [Torppa, J.; Kaasalainen, M.; Michalowski, T.; Kwiatkowski, T.; et al. (2003) Icarus 164, 346-383.], [Faury, G. (2009) Bull. Amer. Astron. Soc. 40.], [Behrend, R. (2010) Observatoire de Geneve web site, http://obswww.unige.ch/~behrend/page_cou.html], [Belskaya, I.N.; Fornasier, S.; Krugly, Yu.N.; Shevchenko, V.G.; et al. (2010) Astron. Astrophys. 515, A29.], [Carry, B.; Kaasalainen, M.; Leyrat, C.; Merline, W.J.; et al. (2010) Astron. Astrophys. 523, A94.], [Behrend, R. (2018) Observatoire de Geneve web site, http://obswww.unige.ch/~behrend/page_cou.html], [Muinonen, K.; Torppa, J.; Wang, X.-B.; Cellino, A.; Penttila, A. (2020) Astron. Astrophys. 642, A138.], [Vernazza, P.; Ferrais, M.; Jorda, L.; Hanus, J.; et al. (2021) Astron. Astrophys 654, id. A56.], [Ferrais, M.; Vernazza, P.; Jorda, L.; Jehin, E.; et al. (2022) Minor Planet Bull. 49, 307-313.]"},{"sigma":"0.4/0.4","ref":"Sierks et al., Science 334, 487, 2011","title":"pole direction","value":"51.8/+10.8","notes":null,"desc":"spin-pole direction in R.A./Dec.","units":null,"name":"pole"},{"sigma":"0.01","ref":"Sierks et al., Science 334, 487, 2011","title":"geometric albedo","value":"0.19","notes":null,"name":"albedo","units":null,"desc":"geometric albedo"},{"value":"0.686","notes":"#obs=17; phase (min.=3.08, mean=16.43, max.=25.04) deg.","units":null,"name":"BV","desc":"color index B-V magnitude difference","ref":"EAR-A-5-DDR-UBV-MEAN-VALUES-V1.2","sigma":"0.027","title":"B-V"},{"title":"U-B","ref":"EAR-A-5-DDR-UBV-MEAN-VALUES-V1.2","sigma":"0.017","desc":"color index U-B magnitude difference","name":"UB","units":null,"value":"0.189","notes":"#obs=11; phase (min.=3.08, mean=13.14, max.=23.99) deg."},{"value":"M","notes":"used 7 color indices; used ground-based radiometric albedo","units":null,"name":"spec_T","desc":"Tholen spectral taxonomic classification","ref":"EAR-A-5-DDR-TAXONOMY-V4.0","sigma":null,"title":"Tholen spectral type"},{"title":"SMASSII spectral type","ref":"EAR-A-5-DDR-TAXONOMY-V4.0","sigma":null,"desc":"SMASSII spectral taxonomic classification","units":null,"name":"spec_B","notes":"based on a high-resolution spectrum by Xu et al. (1995) or Bus and Binzel (2002)","value":"Xk"}],"signature":{"source":"NASA/JPL Small-Body Database (SBDB) API","version":"1.3"},"orbit":{"pe_used":"DE441","model_pars":[],"not_valid_after":null,"cov_epoch":"2458038.5","data_arc":"58432","comment":null,"n_obs_used":7110,"moid_jup":"2.5","condition_code":"0","t_jup":"3.485","sb_used":"SB441-N16","n_dop_obs_used":null,"rms":"0.37","moid":"1.02","producer":"Otto Matic","epoch":"2461200.5","not_valid_before":null,"soln_date":"2026-06-05 03:03:25","orbit_id":"146","source":"JPL","last_obs":"2026-03-30","first_obs":"1866-04-06","elements":[{"name":"e","units":null,"title":"eccentricity","label":"e","value":"0.165","sigma":"2.1e-09"},{"name":"a","units":"au","title":"semi-major axis","label":"a","value":"2.43","sigma":"1.4e-09"},{"label":"q","title":"perihelion distance","name":"q","units":"au","value":"2.03","sigma":"5.2e-09"},{"units":"deg","name":"i","label":"i","title":"inclination; angle with respect to x-y ecliptic plane","sigma":"2.3e-07","value":"3.06"},{"value":"80.8","sigma":"3.3e-06","name":"om","units":"deg","label":"node","title":"longitude of the ascending node"},{"units":"deg","name":"w","label":"peri","title":"argument of perihelion","value":"250","sigma":"3.4e-06"},{"label":"M","title":"mean anomaly","name":"ma","units":"deg","sigma":"1.1e-06","value":"299"},{"value":"2461436.460","sigma":"4.3e-06","label":"tp","title":"time of perihelion passage","name":"tp","units":"TDB"},{"label":"period","title":"sidereal orbital period","units":"d","name":"per","sigma":"1.2e-06","value":"1390"},{"title":"mean motion","label":"n","name":"n","units":"deg/d","sigma":"2.2e-10","value":"0.259"},{"value":"2.84","sigma":"1.6e-09","title":"aphelion distance","label":"Q","name":"ad","units":"au"}],"equinox":"J2000","n_del_obs_used":null,"two_body":null}}