{"object":{"fullname":"1P/Halley","orbit_class":{"code":"HTC","name":"Halley-type Comet*"},"pha":false,"prefix":"P","kind":"cn","orbit_id":"75","des":"1P","spkid":"1000036","neo":true},"signature":{"source":"NASA/JPL Small-Body Database (SBDB) API","version":"1.3"},"orbit":{"sb_used":"SB441-N16","pe_used":"DE441","epoch":"2439875.5","first_obs":"1835-08-21","rms":"0.61","not_valid_after":null,"not_valid_before":null,"n_dop_obs_used":null,"cov_epoch":"2439875.5","model_pars":[{"desc":"non-gravitational radial acceleration parameter","value":"4.887e-10","name":"A1","n":1,"kind":"EST","title":"non-grav. radial accel.","sigma":"4.E-11","units":"au/d^2"},{"units":"au/d^2","sigma":"4.575E-15","title":"non-grav. transverse accel.","kind":"EST","n":2,"name":"A2","value":"1.555e-10","desc":"non-gravitational transverse acceleration parameter"},{"units":"km","sigma":"27.33","kind":"EST","title":"center-of-light/mass offset","n":3,"desc":"offset between the center-of-light and center-of-mass","name":"S0","value":"578"}],"data_arc":"57852","last_obs":"1994-01-11","t_jup":"-0.598","n_obs_used":8518,"source":"JPL","moid":"0.0745","equinox":"J2000","two_body":null,"orbit_id":"75","producer":"Davide Farnocchia","soln_date":"2025-11-21 15:57:34","elements":[{"value":"0.968","title":"eccentricity","name":"e","sigma":"7.6e-09","units":null,"label":"e"},{"name":"a","title":"semi-major axis","value":"17.9","units":"au","sigma":"1e-08","label":"a"},{"sigma":"1.4e-07","units":"au","label":"q","value":"0.575","title":"perihelion distance","name":"q"},{"value":"162","name":"i","title":"inclination; angle with respect to x-y ecliptic plane","label":"i","sigma":"1.5e-05","units":"deg"},{"value":"59.1","title":"longitude of the ascending node","name":"om","sigma":"2e-05","units":"deg","label":"node"},{"label":"peri","units":"deg","sigma":"2.1e-05","name":"w","title":"argument of perihelion","value":"112"},{"name":"ma","title":"mean anomaly","value":"274","units":"deg","sigma":"1.2e-07","label":"M"},{"name":"tp","title":"time of perihelion passage","value":"2446469.974","label":"tp","units":"TDB","sigma":"1.3e-05"},{"value":"27700","name":"per","title":"sidereal orbital period","sigma":"2.3e-05","units":"d","label":"period"},{"label":"n","sigma":"1.1e-11","units":"deg/d","value":"0.013","title":"mean motion","name":"n"},{"units":"au","sigma":"2e-08","label":"Q","title":"aphelion distance","name":"ad","value":"35.3"}],"condition_code":"0","n_del_obs_used":null,"comment":null,"moid_jup":"0.783"},"phys_par":[{"sigma":null,"units":null,"title":"comet total magnitude","notes":null,"ref":"ICQ 2005 Handbook","value":"5.5","name":"M1","desc":"absolute magnitude of comet and coma (i.e. total)"},{"desc":"comet total magnitude slope parameter","name":"K1","ref":"ICQ 2005 Handbook","value":"8.0","notes":null,"title":"comet total magnitude slope","units":null,"sigma":null},{"desc":"absolute magnitude of comet nucleus","ref":"ICQ 2005 Handbook","value":"13.6","name":"M2","notes":null,"title":"comet nuclear magnitude","sigma":null,"units":null},{"notes":null,"name":"K2","value":"5.0","ref":"ICQ 2005 Handbook","desc":"comet nuclear magnitude slope parameter","units":null,"sigma":null,"title":"comet nuclear magnitude slope"},{"desc":"comet nuclear magnitude law phase coefficient","ref":"ICQ 2005 Handbook","value":"0.03","name":"PC","notes":null,"title":"comet nuclear phase coefficient","sigma":null,"units":null},{"notes":null,"desc":"effective body diameter","value":"11.0","ref":"Lamy,P.L.;Toth,I.;Fernandez,Y.R.;Weaver,H.A. (2004) Comets II, pp. 223-264","name":"diameter","sigma":null,"units":"km","title":"diameter"},{"desc":"tri(or bi)-axial body dimensions","value":"14.9x8.2","ref":"Keller et al. (1987) Astron. Astrophys. 187:807-823","name":"extent","notes":"measurements repeatable within 100 to 200 meters","title":"extent","sigma":null,"units":"km"},{"title":"geometric albedo","sigma":"0.01","units":null,"desc":"geometric albedo","value":"0.04","ref":"Earth, Moon, and Planets, v. 89, Issue 1, p. 117-134 (2002)","name":"albedo","notes":null}]}