{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.687","julian_year":2026.687,"time":"2026-09-08T20:05:41.153Z","years_from_j2000":26.687,"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":"k2-258-b","name":"K2-258 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":2158.7410018851415,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":187.6314027,"dec_deg":-1.1609171,"epoch_ra_deg":187.976096,"epoch_dec_deg":-1.309448,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"K2-258","semi_major_axis_km":22290082.7343,"periapsis_km":null,"mass_kg":5.536199613442609e+25,"mass_msun":0.0000278423,"constellation":"Virgo","discovered":"2018","featured":false,"url":"https://spacecatalog.org/object/k2-258-b","radius_km":19134.300000000003,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"K2-258","host_v_mag":13.361,"uncertainties":{"radius_km":[1275.6200000000001,1339.401],"distance_ly":[35.40753636492966,36.588222452264276],"host_mass_solar":[0.08,0.05],"host_radius_solar":[0.03,0.03],"host_temperature_k":[228,198],"semi_major_axis_km":[388954.46381999995,373994.67675],"orbital_period_days":[0.00633,0.00576]},"host_mass_solar":1.21,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":1.31,"planets_in_system":1,"discovery_facility":"K2","host_temperature_k":6351,"orbital_period_days":19.0921,"transit_midpoint_bjd":2457586.2928,"equilibrium_temperature_k":831},"designations":[{"catalog":"Exoplanet","designation":"K2-258 b"},{"catalog":"Host star","designation":"K2-258"}],"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":"2026-09-02T19:50:56.720Z","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."}