{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.671","julian_year":2026.671,"time":"2026-09-02T22:19:09.409Z","years_from_j2000":26.671,"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":"kepler-339-d","name":"Kepler-339 d","class":"terrestrial_planet","category":"exoplanet","object_type":"Terrestrial planet","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":2011.200902861195,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":293.351701,"dec_deg":48.4445922,"epoch_ra_deg":293.539832,"epoch_dec_deg":48.501956,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"Kepler-339","semi_major_axis_km":13613406.233699998,"periapsis_km":null,"mass_kg":8.779086765653328e+25,"mass_msun":0.0000441513,"constellation":"Cygnus","discovered":"2014","featured":false,"url":"https://spacecatalog.org/object/kepler-339-d","radius_km":7462.377,"radius_kind":null,"data_quality":"The published mass and radius imply a density no material has. One of the two is likely an upper limit rather than a measurement.","description":null,"properties":{"host_star":"Kepler-339","host_v_mag":14.706,"eccentricity":0,"uncertainties":{"mass_kg":[5.972167867791379e+25,8.420756693585844e+25],"radius_km":[3380.3930000000005,3380.3930000000005],"distance_ly":[30.46137489685525,30.46137489685525],"host_mass_solar":[0.012,0.01],"host_radius_solar":[0.362,0.362],"host_temperature_k":[200,200],"orbital_period_days":[0.000081,0.000081]},"host_mass_solar":0.87,"inclination_deg":89.23,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":0.802,"planets_in_system":3,"discovery_facility":"Kepler","host_temperature_k":5631,"orbital_period_days":10.558345,"transit_midpoint_bjd":2454969.34663,"equilibrium_temperature_k":796},"designations":[{"catalog":"Exoplanet","designation":"Kepler-339 d"},{"catalog":"Host star","designation":"Kepler-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."}