{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.669","julian_year":2026.669,"time":"2026-09-02T08:24:15.337Z","years_from_j2000":26.669,"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-338-c","name":"Kepler-338 c","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":1802.9859328906032,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":282.9790593,"dec_deg":40.7844188,"epoch_ra_deg":283.196945,"epoch_dec_deg":40.816019,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"Kepler-338","semi_major_axis_km":25730833.760399997,"periapsis_km":null,"mass_kg":3.6310780636171586e+25,"mass_msun":0.0000182612,"constellation":"Lyra","discovered":"2014","featured":false,"url":"https://spacecatalog.org/object/kepler-338-c","radius_km":14924.754,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"Kepler-338","host_v_mag":12.19,"eccentricity":0.03,"uncertainties":{"radius_km":[765.3720000000001,765.3720000000001],"distance_ly":[21.666568171723263,22.188418376070054],"eccentricity":[0.03,0.24],"host_mass_solar":[0.021,0.026],"host_radius_solar":[0.082,0.082],"host_temperature_k":[77,77],"orbital_period_days":[0.000158,0.000158]},"host_mass_solar":1.105,"inclination_deg":89.61,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":1.735,"planets_in_system":4,"discovery_facility":"Kepler","host_temperature_k":5923,"orbital_period_days":24.310856,"transit_midpoint_bjd":2454970.04147,"equilibrium_temperature_k":831},"designations":[{"catalog":"Exoplanet","designation":"Kepler-338 c"}],"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."}