{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.679","julian_year":2026.679,"time":"2026-09-05T20:17:03.526Z","years_from_j2000":26.679,"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":"k2-339-b","name":"K2-339 b","class":"super_earth","category":"exoplanet","object_type":"Super-Earth","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":1175.3371227400567,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":130.082542,"dec_deg":18.6929046,"epoch_ra_deg":130.465711,"epoch_dec_deg":18.59798,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"K2-339","semi_major_axis_km":null,"periapsis_km":null,"mass_kg":2.5978930224892496e+25,"mass_msun":0.0000130652,"constellation":"Cancer","discovered":"2021","featured":false,"url":"https://spacecatalog.org/object/k2-339-b","radius_km":12245.952000000001,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"K2-339","host_v_mag":14.487,"uncertainties":{"radius_km":[765.3720000000001,1211.8390000000002],"distance_ly":[17.077547937248685,17.077547937248685],"host_mass_solar":[0.03,0.04],"host_radius_solar":[0.03,0.03],"host_temperature_k":[84,86],"orbital_period_days":[0.000113,0.000116]},"host_mass_solar":0.74,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":0.72,"planets_in_system":1,"discovery_facility":"K2","host_temperature_k":4857,"orbital_period_days":19.507428,"transit_midpoint_bjd":2457153.004667,"equilibrium_temperature_k":508},"designations":[{"catalog":"Exoplanet","designation":"K2-339 b"},{"catalog":"Host star","designation":"K2-339"}],"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."}