{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.668","julian_year":2026.668,"time":"2026-09-02T01:40:09.735Z","years_from_j2000":26.668,"frame":"date","applied":"Proper motion, then precession and nutation. The catalogued J2000 position is carried along the great circle the object's own published motion puts it on, at a constant velocity, and the result is referred to the true equator and equinox of this instant. Those are separate things: the motion moves the object, and the rotation turns the grid under it by about fifty arcseconds a year, with nutation adding up to another seventeen.","excluded":"Parallax, the radial-velocity perspective term, aberration and refraction; each is below the accuracy of the catalogued positions themselves. An object with no published proper motion comes back where the catalogue has it rather than at a fabricated zero, and says so with a null pm_ra_mas_yr. A body with no fixed position is not propagated at all — its place comes from an ephemeris, which is what /api/v1/visible answers with."},"slug":"k2-321-b","name":"K2-321 b","class":"neptune_like_planet","category":"exoplanet","object_type":"Neptune-like planet","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":253.38697597160535,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":156.4054989,"dec_deg":2.5138829,"epoch_ra_deg":156.752125,"epoch_dec_deg":2.377648,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"K2-321","semi_major_axis_km":4247083.549172999,"periapsis_km":null,"mass_kg":2.9024735837466105e+25,"mass_msun":0.000014597,"constellation":"Sextans","discovered":"2020","featured":false,"url":"https://spacecatalog.org/object/k2-321-b","radius_km":13083.035976007002,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"K2-321","host_v_mag":13.677,"eccentricity":0.44,"uncertainties":{"radius_km":[857.904007837,1072.379993851],"distance_ly":[1.0572358983688237,1.0572358983688237],"eccentricity":[0.23,0.26],"host_mass_solar":[0.03,0.03],"inclination_deg":[1.1,2.5],"host_radius_solar":[0.031,0.031],"host_temperature_k":[520,510],"semi_major_axis_km":[74798.93535,71806.977936],"orbital_period_days":[0.0000019,0.0000017],"argument_of_periastron_deg":[140,96]},"host_mass_solar":0.578,"inclination_deg":86.1,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":0.595,"planets_in_system":1,"discovery_facility":"K2","host_temperature_k":3750,"orbital_period_days":2.2979749,"transit_midpoint_bjd":2458141.26759,"equilibrium_temperature_k":830,"argument_of_periastron_deg":45},"designations":[{"catalog":"Exoplanet","designation":"K2-321 b"},{"catalog":"Host star","designation":"K2-321"}],"source":{"id":"exoplanet_archive","name":"NASA Exoplanet Archive (Planetary Systems Composite Parameters)","url":"https://exoplanetarchive.ipac.caltech.edu/cgi-bin/TblView/nph-tblView?app=ExoTbls&config=PSCompPars","license":"Public domain (NASA)"},"updated_at":"2026-09-01T22:58:55.274Z","attribution":"Data from SpaceCatalog.org. Individual records carry their source and license in `source`; attribution is required for CC-BY and CC-BY-SA rows."}